Vertical Antenna And ALA 100 Comparisons
To Whom It May Concern: Additions and revisions have been made to two
of my articles about vertical antennas and the ALA 100 on the www.kongsfjord.com web site. The articles are (1) "Measurements Of Some Antennas Signal To Man Made Noise Ratios In The Daytime MW And LW Bands," and (2) "Some Of My Favorite Small Antennas For MW And LW." In the first article an additional comparison of the ALA 100 was made with an active whip antenna. The ALA 100 and active whip had about the same signal to man made noise ratio. In the second article some information was added about reducing noise in active whip antennas due to what are believed to be ground loops in the DC feed. |
Vertical Antenna And ALA 100 Comparisons
In article .com,
"R390A" wrote: To Whom It May Concern: Additions and revisions have been made to two of my articles about vertical antennas and the ALA 100 on the www.kongsfjord.com web site. The articles are (1) "Measurements Of Some Antennas Signal To Man Made Noise Ratios In The Daytime MW And LW Bands," and (2) "Some Of My Favorite Small Antennas For MW And LW." In the first article an additional comparison of the ALA 100 was made with an active whip antenna. The ALA 100 and active whip had about the same signal to man made noise ratio. In the second article some information was added about reducing noise in active whip antennas due to what are believed to be ground loops in the DC feed. There is no http://www.kongsfjord.com but there is a http://www.kongsfjord.no/ -- Telamon Ventura, California |
Vertical Antenna And ALA 100 Comparisons
In article .com,
"R390A" wrote: To Whom It May Concern: Additions and revisions have been made to two of my articles about vertical antennas and the ALA 100 on the www.kongsfjord.com web site. The articles are (1) "Measurements Of Some Antennas Signal To Man Made Noise Ratios In The Daytime MW And LW Bands," and (2) "Some Of My Favorite Small Antennas For MW And LW." In the first article an additional comparison of the ALA 100 was made with an active whip antenna. The ALA 100 and active whip had about the same signal to man made noise ratio. In the second article some information was added about reducing noise in active whip antennas due to what are believed to be ground loops in the DC feed. The link is dead. http://www.kongsfjord.no/dl/Antennas...ome%20Antennas %20Signal%20To%20Man%20Made%20Noise%20Ratio.pdf -- Telamon Ventura, California |
Vertical Antenna And ALA 100 Comparisons
Try www.kongsfjord.no and then click on The Dallas Files.
Telamon wrote: In article .com, "R390A" wrote: To Whom It May Concern: Additions and revisions have been made to two of my articles about vertical antennas and the ALA 100 on the www.kongsfjord.com web site. The articles are (1) "Measurements Of Some Antennas Signal To Man Made Noise Ratios In The Daytime MW And LW Bands," and (2) "Some Of My Favorite Small Antennas For MW And LW." In the first article an additional comparison of the ALA 100 was made with an active whip antenna. The ALA 100 and active whip had about the same signal to man made noise ratio. In the second article some information was added about reducing noise in active whip antennas due to what are believed to be ground loops in the DC feed. The link is dead. http://www.kongsfjord.no/dl/Antennas...ome%20Antennas %20Signal%20To%20Man%20Made%20Noise%20Ratio.pdf -- Telamon Ventura, California |
Vertical Antenna And ALA 100 Comparisons
Oops. It should be www.kongsfjord.no
R390A wrote: To Whom It May Concern: Additions and revisions have been made to two of my articles about vertical antennas and the ALA 100 on the www.kongsfjord.com web site. The articles are (1) "Measurements Of Some Antennas Signal To Man Made Noise Ratios In The Daytime MW And LW Bands," and (2) "Some Of My Favorite Small Antennas For MW And LW." In the first article an additional comparison of the ALA 100 was made with an active whip antenna. The ALA 100 and active whip had about the same signal to man made noise ratio. In the second article some information was added about reducing noise in active whip antennas due to what are believed to be ground loops in the DC feed. |
Vertical Antenna And ALA 100 Comparisons
In article .com,
"R390A" wrote: Telamon wrote: In article .com, "R390A" wrote: To Whom It May Concern: Additions and revisions have been made to two of my articles about vertical antennas and the ALA 100 on the www.kongsfjord.com web site. The articles are (1) "Measurements Of Some Antennas Signal To Man Made Noise Ratios In The Daytime MW And LW Bands," and (2) "Some Of My Favorite Small Antennas For MW And LW." In the first article an additional comparison of the ALA 100 was made with an active whip antenna. The ALA 100 and active whip had about the same signal to man made noise ratio. In the second article some information was added about reducing noise in active whip antennas due to what are believed to be ground loops in the DC feed. The link is dead. http://www.kongsfjord.no/dl/Antennas...ome%20Antennas %20Signal%20To%20Man%20Made%20Noise%20Ratio.pdf Try www.kongsfjord.no and then click on The Dallas Files. That link worked. Looking at your data I'm at a disadvantage not knowing which are radio stations and which are computer noise other than KNOE 540 kHz you specifically pointed out. Another problem for me is the loop antenna gain looks to be about 10 dB less than the other antennas. While actually not a problem for signal to noise measurements it does make the sweep look different to a person that did not make the measurement. Antennas in different locations around your house is not exactly apples to apples comparison. If your spectrum analyzer has a max hold on the trace that would be a help in measuring the top of the noise floor. A clear difference in S/N would be the last pair on page three 1500 to 2000 KHz where the ALA-100 looks to be 22 dB (-42 S to -60 N) compared to the vertical 33 dB (-32 S to -65 N). One problem for me here is I don't know what the analyzer noise floor itself is at this point and I can see that the loop has 10 dB less gain than the other antennas. Assuming that the analyzer noise floor is -70 dBm and lower would make this comparison valid. A simple check of just disconnecting the cable from the analyzer at those settings would show the instrument noise floor. Using max hold would make the noise floor less ambiguous. Due to my disadvantages noted I can't draw any firm conclusions based on the analyzer pictures. ************* I have to take exception to the wording you ascribe to other people such as myself about a "belief in magnetic field sensitive antennas". I rely on belief only when I have no other choice as a fall back to no being able to test a thesis empirically. An electrically small shielded loop antenna will respond very poorly to a local electric induction field and very well to a magnetic one. An electrically small dipole would be just the opposite in response to induction fields. This is theoretically and empirically correct. I have much experience using these types of antennas monitoring for induction fields and they behaved as theory predicted. When poorly designed electronic devices generate induction fields the electric fields have the tendency to spread farther from the source than the magnetic fields. This is a generalization but knowing this leads to the conclusion that a loop would pick up less of the locally generated noise most of the time or in other words it would be an advantage to use over a dipole. Most people that have local noise problems and purchase a loop antenna such as the Wellbrook find that their listening situation is greatly improved. I use a non-amplified folded dipole and non-amplified shielded loop. The loop picks up much less of the local noise and picks up as much signal as the folded dipole depending on the band. Notice that belief is not required for any of the foregoing. ************ You have the right idea about field impedance vs distance but that relationship is appropriate for transmitting antennas that are efficient. Here the subject is inefficient noise sources. Here the induction fields fall off rapidly compared to an efficient antenna. ************* I just noticed that your ALA 100 is pretty big and not electrically small at SW frequencies. This means it will also respond to electric fields and being broadband will raise the noise floor. Your 60 foot amplified loop is 10 feet bigger than my passive loop. Why do you need an amplifier with a 60 foot loop? Normally when I consider an amplified loop it more like 1 to 3 foot in diameter. -- Telamon Ventura, California |
Vertical Antenna And ALA 100 Comparisons
Telamon wrote: In article .com, "R390A" wrote: Telamon wrote: In article .com, "R390A" wrote: To Whom It May Concern: Additions and revisions have been made to two of my articles about vertical antennas and the ALA 100 on the www.kongsfjord.com web site. The articles are (1) "Measurements Of Some Antennas Signal To Man Made Noise Ratios In The Daytime MW And LW Bands," and (2) "Some Of My Favorite Small Antennas For MW And LW." In the first article an additional comparison of the ALA 100 was made with an active whip antenna. The ALA 100 and active whip had about the same signal to man made noise ratio. In the second article some information was added about reducing noise in active whip antennas due to what are believed to be ground loops in the DC feed. The link is dead. http://www.kongsfjord.no/dl/Antennas...ome%20Antennas %20Signal%20To%20Man%20Made%20Noise%20Ratio.pdf Try www.kongsfjord.no and then click on The Dallas Files. That link worked. Looking at your data I'm at a disadvantage not knowing which are radio stations and which are computer noise other than KNOE 540 kHz you specifically pointed out. Another problem for me is the loop antenna gain looks to be about 10 dB less than the other antennas. While actually not a problem for signal to noise measurements it does make the sweep look different to a person that did not make the measurement. Antennas in different locations around your house is not exactly apples to apples comparison. If your spectrum analyzer has a max hold on the trace that would be a help in measuring the top of the noise floor. A clear difference in S/N would be the last pair on page three 1500 to 2000 KHz where the ALA-100 looks to be 22 dB (-42 S to -60 N) compared to the vertical 33 dB (-32 S to -65 N). One problem for me here is I don't know what the analyzer noise floor itself is at this point and I can see that the loop has 10 dB less gain than the other antennas. Assuming that the analyzer noise floor is -70 dBm and lower would make this comparison valid. A simple check of just disconnecting the cable from the analyzer at those settings would show the instrument noise floor. Using max hold would make the noise floor less ambiguous. Due to my disadvantages noted I can't draw any firm conclusions based on the analyzer pictures. I'm an audio person, but noise should be measured in terms of root hertz. Thus the noise floor you see is a function of the bandwidth of the tracking filter. As you go narrower, the noise floor should drop. ************* I have to take exception to the wording you ascribe to other people such as myself about a "belief in magnetic field sensitive antennas". I rely on belief only when I have no other choice as a fall back to no being able to test a thesis empirically. An electrically small shielded loop antenna will respond very poorly to a local electric induction field and very well to a magnetic one. An electrically small dipole would be just the opposite in response to induction fields. This is theoretically and empirically correct. I have much experience using these types of antennas monitoring for induction fields and they behaved as theory predicted. When poorly designed electronic devices generate induction fields the electric fields have the tendency to spread farther from the source than the magnetic fields. This is a generalization but knowing this leads to the conclusion that a loop would pick up less of the locally generated noise most of the time or in other words it would be an advantage to use over a dipole. Most people that have local noise problems and purchase a loop antenna such as the Wellbrook find that their listening situation is greatly improved. I use a non-amplified folded dipole and non-amplified shielded loop. The loop picks up much less of the local noise and picks up as much signal as the folded dipole depending on the band. Notice that belief is not required for any of the foregoing. ************ You have the right idea about field impedance vs distance but that relationship is appropriate for transmitting antennas that are efficient. Here the subject is inefficient noise sources. Here the induction fields fall off rapidly compared to an efficient antenna. ************* I just noticed that your ALA 100 is pretty big and not electrically small at SW frequencies. This means it will also respond to electric fields and being broadband will raise the noise floor. Your 60 foot amplified loop is 10 feet bigger than my passive loop. Why do you need an amplifier with a 60 foot loop? Normally when I consider an amplified loop it more like 1 to 3 foot in diameter. Here again, I believe being broadband increases the integrated noise, but not necessarily the noise measured per root Hz. The final bandwidth of the filter of the radio determines the integrated noise. Say the noise was 1nV/root Hz. Say the filter bandwidth was 6Khz. Multiply the square root of 6Khz times 1nV/Root Hz to get 77.5nV. -- Telamon Ventura, California |
Vertical Antenna And ALA 100 Comparisons
Telamon wrote: In article . com, wrote: Telamon wrote: In article .com, "R390A" wrote: Telamon wrote: In article .com, "R390A" wrote: To Whom It May Concern: Additions and revisions have been made to two of my articles about vertical antennas and the ALA 100 on the www.kongsfjord.com web site. The articles are (1) "Measurements Of Some Antennas Signal To Man Made Noise Ratios In The Daytime MW And LW Bands," and (2) "Some Of My Favorite Small Antennas For MW And LW." In the first article an additional comparison of the ALA 100 was made with an active whip antenna. The ALA 100 and active whip had about the same signal to man made noise ratio. In the second article some information was added about reducing noise in active whip antennas due to what are believed to be ground loops in the DC feed. The link is dead. http://www.kongsfjord.no/dl/Antennas...%20Of%20Some%2 0Antenna s %20Signal%20To%20Man%20Made%20Noise%20Ratio.pdf Try www.kongsfjord.no and then click on The Dallas Files. That link worked. Looking at your data I'm at a disadvantage not knowing which are radio stations and which are computer noise other than KNOE 540 kHz you specifically pointed out. Another problem for me is the loop antenna gain looks to be about 10 dB less than the other antennas. While actually not a problem for signal to noise measurements it does make the sweep look different to a person that did not make the measurement. Antennas in different locations around your house is not exactly apples to apples comparison. If your spectrum analyzer has a max hold on the trace that would be a help in measuring the top of the noise floor. A clear difference in S/N would be the last pair on page three 1500 to 2000 KHz where the ALA-100 looks to be 22 dB (-42 S to -60 N) compared to the vertical 33 dB (-32 S to -65 N). One problem for me here is I don't know what the analyzer noise floor itself is at this point and I can see that the loop has 10 dB less gain than the other antennas. Assuming that the analyzer noise floor is -70 dBm and lower would make this comparison valid. A simple check of just disconnecting the cable from the analyzer at those settings would show the instrument noise floor. Using max hold would make the noise floor less ambiguous. Due to my disadvantages noted I can't draw any firm conclusions based on the analyzer pictures. I'm an audio person, but noise should be measured in terms of root hertz. Thus the noise floor you see is a function of the bandwidth of the tracking filter. As you go narrower, the noise floor should drop. ************* I have to take exception to the wording you ascribe to other people such as myself about a "belief in magnetic field sensitive antennas". I rely on belief only when I have no other choice as a fall back to no being able to test a thesis empirically. An electrically small shielded loop antenna will respond very poorly to a local electric induction field and very well to a magnetic one. An electrically small dipole would be just the opposite in response to induction fields. This is theoretically and empirically correct. I have much experience using these types of antennas monitoring for induction fields and they behaved as theory predicted. When poorly designed electronic devices generate induction fields the electric fields have the tendency to spread farther from the source than the magnetic fields. This is a generalization but knowing this leads to the conclusion that a loop would pick up less of the locally generated noise most of the time or in other words it would be an advantage to use over a dipole. Most people that have local noise problems and purchase a loop antenna such as the Wellbrook find that their listening situation is greatly improved. I use a non-amplified folded dipole and non-amplified shielded loop. The loop picks up much less of the local noise and picks up as much signal as the folded dipole depending on the band. Notice that belief is not required for any of the foregoing. ************ You have the right idea about field impedance vs distance but that relationship is appropriate for transmitting antennas that are efficient. Here the subject is inefficient noise sources. Here the induction fields fall off rapidly compared to an efficient antenna. ************* I just noticed that your ALA 100 is pretty big and not electrically small at SW frequencies. This means it will also respond to electric fields and being broadband will raise the noise floor. Your 60 foot amplified loop is 10 feet bigger than my passive loop. Why do you need an amplifier with a 60 foot loop? Normally when I consider an amplified loop it more like 1 to 3 foot in diameter. Here again, I believe being broadband increases the integrated noise, but not necessarily the noise measured per root Hz. The final bandwidth of the filter of the radio determines the integrated noise. Say the noise was 1nV/root Hz. Say the filter bandwidth was 6Khz. Multiply the square root of 6Khz times 1nV/Root Hz to get 77.5nV. That's why even if I know the model number of the spectrum analyzer I can not easily know the instrument noise floor in the sweep. The sweep settings will modify the noise floor. I took another look at the measurement pdf and I think it likely that the analyzer noise floor at those settings is lower than the measurement noise in the sweeps and so at least in the last pair of comparison photos on page 3 clearly show that the ALA-100 has a poorer signal to noise than the vertical he is comparing it with. I still don't know about the other sweeps as I don't know what is a radio station and what is the local noise in the sweep. When I did work on a range I would turn the DUT on and off to see what actually popped up on the sweep when the DUT is turned on. You had to do this on a range where you can't have a large enough screen room due to cost. I'm sure the author knows what is being generated by the stuff in his house and what is a radio station. It looks to me that although the Wellbrook amplifiers have very good intermodulation numbers but that the noise floor may be high. You would have to put in a larger signal into the Wellbrook to measure the intermodulation products relative to the other antenna amplifiers in the pdf document. Wellbrook does not appear to give a noise figure for the amplifier. The author of the pdf could easily make that measurement since he has an analyzer. Maybe noise is coming in through the power supply connection for the amplifier, the amplifier has a poor noise floor, or the antenna is picking it up. -- Telamon Ventura, California The difficulty in making measurements on the ALA 100 with test instruments is you need a differential drive. I don't know if grounding one side is kosher. |
Vertical Antenna And ALA 100 Comparisons
Telamon wrote: In article .com, "R390A" wrote: Telamon wrote: In article .com, "R390A" wrote: To Whom It May Concern: Additions and revisions have been made to two of my articles about vertical antennas and the ALA 100 on the www.kongsfjord.com web site. The articles are (1) "Measurements Of Some Antennas Signal To Man Made Noise Ratios In The Daytime MW And LW Bands," and (2) "Some Of My Favorite Small Antennas For MW And LW." In the first article an additional comparison of the ALA 100 was made with an active whip antenna. The ALA 100 and active whip had about the same signal to man made noise ratio. In the second article some information was added about reducing noise in active whip antennas due to what are believed to be ground loops in the DC feed. The link is dead. http://www.kongsfjord.no/dl/Antennas...ome%20Antennas %20Signal%20To%20Man%20Made%20Noise%20Ratio.pdf Try www.kongsfjord.no and then click on The Dallas Files. That link worked. Looking at your data I'm at a disadvantage not knowing which are radio stations and which are computer noise other than KNOE 540 kHz you specifically pointed out. Another problem for me is the loop antenna gain looks to be about 10 dB less than the other antennas. While actually not a problem for signal to noise measurements it does make the sweep look different to a person that did not make the measurement. Antennas in different locations around your house is not exactly apples to apples comparison. If your spectrum analyzer has a max hold on the trace that would be a help in measuring the top of the noise floor. A clear difference in S/N would be the last pair on page three 1500 to 2000 KHz where the ALA-100 looks to be 22 dB (-42 S to -60 N) compared to the vertical 33 dB (-32 S to -65 N). One problem for me here is I don't know what the analyzer noise floor itself is at this point and I can see that the loop has 10 dB less gain than the other antennas. Assuming that the analyzer noise floor is -70 dBm and lower would make this comparison valid. A simple check of just disconnecting the cable from the analyzer at those settings would show the instrument noise floor. Using max hold would make the noise floor less ambiguous. Due to my disadvantages noted I can't draw any firm conclusions based on the analyzer pictures. ************* I have to take exception to the wording you ascribe to other people such as myself about a "belief in magnetic field sensitive antennas". I rely on belief only when I have no other choice as a fall back to no being able to test a thesis empirically. An electrically small shielded loop antenna will respond very poorly to a local electric induction field and very well to a magnetic one. An electrically small dipole would be just the opposite in response to induction fields. This is theoretically and empirically correct. I have much experience using these types of antennas monitoring for induction fields and they behaved as theory predicted. When poorly designed electronic devices generate induction fields the electric fields have the tendency to spread farther from the source than the magnetic fields. This is a generalization but knowing this leads to the conclusion that a loop would pick up less of the locally generated noise most of the time or in other words it would be an advantage to use over a dipole. Most people that have local noise problems and purchase a loop antenna such as the Wellbrook find that their listening situation is greatly improved. I use a non-amplified folded dipole and non-amplified shielded loop. The loop picks up much less of the local noise and picks up as much signal as the folded dipole depending on the band. Notice that belief is not required for any of the foregoing. ************ You have the right idea about field impedance vs distance but that relationship is appropriate for transmitting antennas that are efficient. Here the subject is inefficient noise sources. Here the induction fields fall off rapidly compared to an efficient antenna. ************* I just noticed that your ALA 100 is pretty big and not electrically small at SW frequencies. This means it will also respond to electric fields and being broadband will raise the noise floor. Your 60 foot amplified loop is 10 feet bigger than my passive loop. Why do you need an amplifier with a 60 foot loop? Normally when I consider an amplified loop it more like 1 to 3 foot in diameter. -- Telamon Ventura, California How the hell am I going to put up a 45 ft vertical antenna? I see this article is from the guy that claims elliptic filters reduce fading. Well, enough said. Next! |
Vertical Antenna And ALA 100 Comparisons
In article . com,
wrote: Telamon wrote: In article . com, wrote: Telamon wrote: In article .com, "R390A" wrote: Telamon wrote: In article .com, "R390A" wrote: To Whom It May Concern: Additions and revisions have been made to two of my articles about vertical antennas and the ALA 100 on the www.kongsfjord.com web site. The articles are (1) "Measurements Of Some Antennas Signal To Man Made Noise Ratios In The Daytime MW And LW Bands," and (2) "Some Of My Favorite Small Antennas For MW And LW." In the first article an additional comparison of the ALA 100 was made with an active whip antenna. The ALA 100 and active whip had about the same signal to man made noise ratio. In the second article some information was added about reducing noise in active whip antennas due to what are believed to be ground loops in the DC feed. The link is dead. http://www.kongsfjord.no/dl/Antennas...%20Of%20Some%2 0Antenna s %20Signal%20To%20Man%20Made%20Noise%20Ratio.pdf Try www.kongsfjord.no and then click on The Dallas Files. That link worked. Looking at your data I'm at a disadvantage not knowing which are radio stations and which are computer noise other than KNOE 540 kHz you specifically pointed out. Another problem for me is the loop antenna gain looks to be about 10 dB less than the other antennas. While actually not a problem for signal to noise measurements it does make the sweep look different to a person that did not make the measurement. Antennas in different locations around your house is not exactly apples to apples comparison. If your spectrum analyzer has a max hold on the trace that would be a help in measuring the top of the noise floor. A clear difference in S/N would be the last pair on page three 1500 to 2000 KHz where the ALA-100 looks to be 22 dB (-42 S to -60 N) compared to the vertical 33 dB (-32 S to -65 N). One problem for me here is I don't know what the analyzer noise floor itself is at this point and I can see that the loop has 10 dB less gain than the other antennas. Assuming that the analyzer noise floor is -70 dBm and lower would make this comparison valid. A simple check of just disconnecting the cable from the analyzer at those settings would show the instrument noise floor. Using max hold would make the noise floor less ambiguous. Due to my disadvantages noted I can't draw any firm conclusions based on the analyzer pictures. I'm an audio person, but noise should be measured in terms of root hertz. Thus the noise floor you see is a function of the bandwidth of the tracking filter. As you go narrower, the noise floor should drop. ************* I have to take exception to the wording you ascribe to other people such as myself about a "belief in magnetic field sensitive antennas". I rely on belief only when I have no other choice as a fall back to no being able to test a thesis empirically. An electrically small shielded loop antenna will respond very poorly to a local electric induction field and very well to a magnetic one. An electrically small dipole would be just the opposite in response to induction fields. This is theoretically and empirically correct. I have much experience using these types of antennas monitoring for induction fields and they behaved as theory predicted. When poorly designed electronic devices generate induction fields the electric fields have the tendency to spread farther from the source than the magnetic fields. This is a generalization but knowing this leads to the conclusion that a loop would pick up less of the locally generated noise most of the time or in other words it would be an advantage to use over a dipole. Most people that have local noise problems and purchase a loop antenna such as the Wellbrook find that their listening situation is greatly improved. I use a non-amplified folded dipole and non-amplified shielded loop. The loop picks up much less of the local noise and picks up as much signal as the folded dipole depending on the band. Notice that belief is not required for any of the foregoing. ************ You have the right idea about field impedance vs distance but that relationship is appropriate for transmitting antennas that are efficient. Here the subject is inefficient noise sources. Here the induction fields fall off rapidly compared to an efficient antenna. ************* I just noticed that your ALA 100 is pretty big and not electrically small at SW frequencies. This means it will also respond to electric fields and being broadband will raise the noise floor. Your 60 foot amplified loop is 10 feet bigger than my passive loop. Why do you need an amplifier with a 60 foot loop? Normally when I consider an amplified loop it more like 1 to 3 foot in diameter. Here again, I believe being broadband increases the integrated noise, but not necessarily the noise measured per root Hz. The final bandwidth of the filter of the radio determines the integrated noise. Say the noise was 1nV/root Hz. Say the filter bandwidth was 6Khz. Multiply the square root of 6Khz times 1nV/Root Hz to get 77.5nV. That's why even if I know the model number of the spectrum analyzer I can not easily know the instrument noise floor in the sweep. The sweep settings will modify the noise floor. I took another look at the measurement pdf and I think it likely that the analyzer noise floor at those settings is lower than the measurement noise in the sweeps and so at least in the last pair of comparison photos on page 3 clearly show that the ALA-100 has a poorer signal to noise than the vertical he is comparing it with. I still don't know about the other sweeps as I don't know what is a radio station and what is the local noise in the sweep. When I did work on a range I would turn the DUT on and off to see what actually popped up on the sweep when the DUT is turned on. You had to do this on a range where you can't have a large enough screen room due to cost. I'm sure the author knows what is being generated by the stuff in his house and what is a radio station. It looks to me that although the Wellbrook amplifiers have very good intermodulation numbers but that the noise floor may be high. You would have to put in a larger signal into the Wellbrook to measure the intermodulation products relative to the other antenna amplifiers in the pdf document. Wellbrook does not appear to give a noise figure for the amplifier. The author of the pdf could easily make that measurement since he has an analyzer. Maybe noise is coming in through the power supply connection for the amplifier, the amplifier has a poor noise floor, or the antenna is picking it up. The difficulty in making measurements on the ALA 100 with test instruments is you need a differential drive. I don't know if grounding one side is kosher. Grounding one side would not be acceptable. I would use a simple test BALUN to drive the input. -- Telamon Ventura, California |
Vertical Antenna And ALA 100 Comparisons
Divorced brunette woman next door,,, she isn't so brunete any
more.Doggy,she just now took me out in the front yard.Brunette woman next door,she was tossin bits of chicken over in doggys front yard.(I told that woman,Don't toss any chicken bones over here.She said,Oh,I won't) Woman has a new boyfriend,,, he works offshore,oil something.She said he is going to give her a male Mastiff Dog. She done dyed her hair from brunette to brown. cuhulin |
Vertical Antenna And ALA 100 Comparisons
www.devilfinder.com Greyfriars Bobby
Yeah,that's it. Check out the Statue of Molly Malone in Dublin too. cuhulin |
Vertical Antenna And ALA 100 Comparisons
Telamon wrote: In article . com, wrote: Telamon wrote: In article . com, wrote: Telamon wrote: In article .com, "R390A" wrote: Telamon wrote: In article .com, "R390A" wrote: To Whom It May Concern: Additions and revisions have been made to two of my articles about vertical antennas and the ALA 100 on the www.kongsfjord.com web site. The articles are (1) "Measurements Of Some Antennas Signal To Man Made Noise Ratios In The Daytime MW And LW Bands," and (2) "Some Of My Favorite Small Antennas For MW And LW." In the first article an additional comparison of the ALA 100 was made with an active whip antenna. The ALA 100 and active whip had about the same signal to man made noise ratio. In the second article some information was added about reducing noise in active whip antennas due to what are believed to be ground loops in the DC feed. The link is dead. http://www.kongsfjord.no/dl/Antennas...%20Of%20Some%2 0Antenna s %20Signal%20To%20Man%20Made%20Noise%20Ratio.pdf Try www.kongsfjord.no and then click on The Dallas Files. That link worked. Looking at your data I'm at a disadvantage not knowing which are radio stations and which are computer noise other than KNOE 540 kHz you specifically pointed out. Another problem for me is the loop antenna gain looks to be about 10 dB less than the other antennas. While actually not a problem for signal to noise measurements it does make the sweep look different to a person that did not make the measurement. Antennas in different locations around your house is not exactly apples to apples comparison. If your spectrum analyzer has a max hold on the trace that would be a help in measuring the top of the noise floor. A clear difference in S/N would be the last pair on page three 1500 to 2000 KHz where the ALA-100 looks to be 22 dB (-42 S to -60 N) compared to the vertical 33 dB (-32 S to -65 N). One problem for me here is I don't know what the analyzer noise floor itself is at this point and I can see that the loop has 10 dB less gain than the other antennas. Assuming that the analyzer noise floor is -70 dBm and lower would make this comparison valid. A simple check of just disconnecting the cable from the analyzer at those settings would show the instrument noise floor. Using max hold would make the noise floor less ambiguous. Due to my disadvantages noted I can't draw any firm conclusions based on the analyzer pictures. I'm an audio person, but noise should be measured in terms of root hertz. Thus the noise floor you see is a function of the bandwidth of the tracking filter. As you go narrower, the noise floor should drop. ************* I have to take exception to the wording you ascribe to other people such as myself about a "belief in magnetic field sensitive antennas". I rely on belief only when I have no other choice as a fall back to no being able to test a thesis empirically. An electrically small shielded loop antenna will respond very poorly to a local electric induction field and very well to a magnetic one. An electrically small dipole would be just the opposite in response to induction fields. This is theoretically and empirically correct. I have much experience using these types of antennas monitoring for induction fields and they behaved as theory predicted. When poorly designed electronic devices generate induction fields the electric fields have the tendency to spread farther from the source than the magnetic fields. This is a generalization but knowing this leads to the conclusion that a loop would pick up less of the locally generated noise most of the time or in other words it would be an advantage to use over a dipole. Most people that have local noise problems and purchase a loop antenna such as the Wellbrook find that their listening situation is greatly improved. I use a non-amplified folded dipole and non-amplified shielded loop. The loop picks up much less of the local noise and picks up as much signal as the folded dipole depending on the band. Notice that belief is not required for any of the foregoing. ************ You have the right idea about field impedance vs distance but that relationship is appropriate for transmitting antennas that are efficient. Here the subject is inefficient noise sources. Here the induction fields fall off rapidly compared to an efficient antenna. ************* I just noticed that your ALA 100 is pretty big and not electrically small at SW frequencies. This means it will also respond to electric fields and being broadband will raise the noise floor. Your 60 foot amplified loop is 10 feet bigger than my passive loop. Why do you need an amplifier with a 60 foot loop? Normally when I consider an amplified loop it more like 1 to 3 foot in diameter. Here again, I believe being broadband increases the integrated noise, but not necessarily the noise measured per root Hz. The final bandwidth of the filter of the radio determines the integrated noise. Say the noise was 1nV/root Hz. Say the filter bandwidth was 6Khz. Multiply the square root of 6Khz times 1nV/Root Hz to get 77.5nV. That's why even if I know the model number of the spectrum analyzer I can not easily know the instrument noise floor in the sweep. The sweep settings will modify the noise floor. I took another look at the measurement pdf and I think it likely that the analyzer noise floor at those settings is lower than the measurement noise in the sweeps and so at least in the last pair of comparison photos on page 3 clearly show that the ALA-100 has a poorer signal to noise than the vertical he is comparing it with. I still don't know about the other sweeps as I don't know what is a radio station and what is the local noise in the sweep. When I did work on a range I would turn the DUT on and off to see what actually popped up on the sweep when the DUT is turned on. You had to do this on a range where you can't have a large enough screen room due to cost. I'm sure the author knows what is being generated by the stuff in his house and what is a radio station. It looks to me that although the Wellbrook amplifiers have very good intermodulation numbers but that the noise floor may be high. You would have to put in a larger signal into the Wellbrook to measure the intermodulation products relative to the other antenna amplifiers in the pdf document. Wellbrook does not appear to give a noise figure for the amplifier. The author of the pdf could easily make that measurement since he has an analyzer. Maybe noise is coming in through the power supply connection for the amplifier, the amplifier has a poor noise floor, or the antenna is picking it up. The difficulty in making measurements on the ALA 100 with test instruments is you need a differential drive. I don't know if grounding one side is kosher. Grounding one side would not be acceptable. I would use a simple test BALUN to drive the input. -- Telamon Ventura, California Yeah, but then what are you testing. The ALA 100 or the balun. Good instrumentation isn't simple. |
Vertical Antenna And ALA 100 Comparisons
In article . com,
wrote: Telamon wrote: In article . com, wrote: Telamon wrote: In article . com, wrote: Telamon wrote: In article .com, "R390A" wrote: Telamon wrote: In article .com, "R390A" wrote: To Whom It May Concern: Additions and revisions have been made to two of my articles about vertical antennas and the ALA 100 on the www.kongsfjord.com web site. The articles are (1) "Measurements Of Some Antennas Signal To Man Made Noise Ratios In The Daytime MW And LW Bands," and (2) "Some Of My Favorite Small Antennas For MW And LW." In the first article an additional comparison of the ALA 100 was made with an active whip antenna. The ALA 100 and active whip had about the same signal to man made noise ratio. In the second article some information was added about reducing noise in active whip antennas due to what are believed to be ground loops in the DC feed. The link is dead. http://www.kongsfjord.no/dl/Antennas...%20Of%20Some%2 0Antenna s %20Signal%20To%20Man%20Made%20Noise%20Ratio.pdf Try www.kongsfjord.no and then click on The Dallas Files. That link worked. Looking at your data I'm at a disadvantage not knowing which are radio stations and which are computer noise other than KNOE 540 kHz you specifically pointed out. Another problem for me is the loop antenna gain looks to be about 10 dB less than the other antennas. While actually not a problem for signal to noise measurements it does make the sweep look different to a person that did not make the measurement. Antennas in different locations around your house is not exactly apples to apples comparison. If your spectrum analyzer has a max hold on the trace that would be a help in measuring the top of the noise floor. A clear difference in S/N would be the last pair on page three 1500 to 2000 KHz where the ALA-100 looks to be 22 dB (-42 S to -60 N) compared to the vertical 33 dB (-32 S to -65 N). One problem for me here is I don't know what the analyzer noise floor itself is at this point and I can see that the loop has 10 dB less gain than the other antennas. Assuming that the analyzer noise floor is -70 dBm and lower would make this comparison valid. A simple check of just disconnecting the cable from the analyzer at those settings would show the instrument noise floor. Using max hold would make the noise floor less ambiguous. Due to my disadvantages noted I can't draw any firm conclusions based on the analyzer pictures. I'm an audio person, but noise should be measured in terms of root hertz. Thus the noise floor you see is a function of the bandwidth of the tracking filter. As you go narrower, the noise floor should drop. ************* I have to take exception to the wording you ascribe to other people such as myself about a "belief in magnetic field sensitive antennas". I rely on belief only when I have no other choice as a fall back to no being able to test a thesis empirically. An electrically small shielded loop antenna will respond very poorly to a local electric induction field and very well to a magnetic one. An electrically small dipole would be just the opposite in response to induction fields. This is theoretically and empirically correct. I have much experience using these types of antennas monitoring for induction fields and they behaved as theory predicted. When poorly designed electronic devices generate induction fields the electric fields have the tendency to spread farther from the source than the magnetic fields. This is a generalization but knowing this leads to the conclusion that a loop would pick up less of the locally generated noise most of the time or in other words it would be an advantage to use over a dipole. Most people that have local noise problems and purchase a loop antenna such as the Wellbrook find that their listening situation is greatly improved. I use a non-amplified folded dipole and non-amplified shielded loop. The loop picks up much less of the local noise and picks up as much signal as the folded dipole depending on the band. Notice that belief is not required for any of the foregoing. ************ You have the right idea about field impedance vs distance but that relationship is appropriate for transmitting antennas that are efficient. Here the subject is inefficient noise sources. Here the induction fields fall off rapidly compared to an efficient antenna. ************* I just noticed that your ALA 100 is pretty big and not electrically small at SW frequencies. This means it will also respond to electric fields and being broadband will raise the noise floor. Your 60 foot amplified loop is 10 feet bigger than my passive loop. Why do you need an amplifier with a 60 foot loop? Normally when I consider an amplified loop it more like 1 to 3 foot in diameter. Here again, I believe being broadband increases the integrated noise, but not necessarily the noise measured per root Hz. The final bandwidth of the filter of the radio determines the integrated noise. Say the noise was 1nV/root Hz. Say the filter bandwidth was 6Khz. Multiply the square root of 6Khz times 1nV/Root Hz to get 77.5nV. That's why even if I know the model number of the spectrum analyzer I can not easily know the instrument noise floor in the sweep. The sweep settings will modify the noise floor. I took another look at the measurement pdf and I think it likely that the analyzer noise floor at those settings is lower than the measurement noise in the sweeps and so at least in the last pair of comparison photos on page 3 clearly show that the ALA-100 has a poorer signal to noise than the vertical he is comparing it with. I still don't know about the other sweeps as I don't know what is a radio station and what is the local noise in the sweep. When I did work on a range I would turn the DUT on and off to see what actually popped up on the sweep when the DUT is turned on. You had to do this on a range where you can't have a large enough screen room due to cost. I'm sure the author knows what is being generated by the stuff in his house and what is a radio station. It looks to me that although the Wellbrook amplifiers have very good intermodulation numbers but that the noise floor may be high. You would have to put in a larger signal into the Wellbrook to measure the intermodulation products relative to the other antenna amplifiers in the pdf document. Wellbrook does not appear to give a noise figure for the amplifier. The author of the pdf could easily make that measurement since he has an analyzer. Maybe noise is coming in through the power supply connection for the amplifier, the amplifier has a poor noise floor, or the antenna is picking it up. The difficulty in making measurements on the ALA 100 with test instruments is you need a differential drive. I don't know if grounding one side is kosher. Grounding one side would not be acceptable. I would use a simple test BALUN to drive the input. -- Telamon Ventura, California Yeah, but then what are you testing. The ALA 100 or the balun. Good instrumentation isn't simple. The BALUN would be simple and you would test it first. It would be no problem at all. -- Telamon Ventura, California |
Vertical Antenna And ALA 100 Comparisons
Telamon wrote: In article . com, wrote: Telamon wrote: In article . com, wrote: Telamon wrote: In article . com, wrote: Telamon wrote: In article .com, "R390A" wrote: Telamon wrote: In article .com, "R390A" wrote: To Whom It May Concern: Additions and revisions have been made to two of my articles about vertical antennas and the ALA 100 on the www.kongsfjord.com web site. The articles are (1) "Measurements Of Some Antennas Signal To Man Made Noise Ratios In The Daytime MW And LW Bands," and (2) "Some Of My Favorite Small Antennas For MW And LW." In the first article an additional comparison of the ALA 100 was made with an active whip antenna. The ALA 100 and active whip had about the same signal to man made noise ratio. In the second article some information was added about reducing noise in active whip antennas due to what are believed to be ground loops in the DC feed. The link is dead. http://www.kongsfjord.no/dl/Antennas...%20Of%20Some%2 0Antenna s %20Signal%20To%20Man%20Made%20Noise%20Ratio.pdf Try www.kongsfjord.no and then click on The Dallas Files. That link worked. Looking at your data I'm at a disadvantage not knowing which are radio stations and which are computer noise other than KNOE 540 kHz you specifically pointed out. Another problem for me is the loop antenna gain looks to be about 10 dB less than the other antennas. While actually not a problem for signal to noise measurements it does make the sweep look different to a person that did not make the measurement. Antennas in different locations around your house is not exactly apples to apples comparison. If your spectrum analyzer has a max hold on the trace that would be a help in measuring the top of the noise floor. A clear difference in S/N would be the last pair on page three 1500 to 2000 KHz where the ALA-100 looks to be 22 dB (-42 S to -60 N) compared to the vertical 33 dB (-32 S to -65 N). One problem for me here is I don't know what the analyzer noise floor itself is at this point and I can see that the loop has 10 dB less gain than the other antennas. Assuming that the analyzer noise floor is -70 dBm and lower would make this comparison valid. A simple check of just disconnecting the cable from the analyzer at those settings would show the instrument noise floor. Using max hold would make the noise floor less ambiguous. Due to my disadvantages noted I can't draw any firm conclusions based on the analyzer pictures. I'm an audio person, but noise should be measured in terms of root hertz. Thus the noise floor you see is a function of the bandwidth of the tracking filter. As you go narrower, the noise floor should drop. ************* I have to take exception to the wording you ascribe to other people such as myself about a "belief in magnetic field sensitive antennas". I rely on belief only when I have no other choice as a fall back to no being able to test a thesis empirically. An electrically small shielded loop antenna will respond very poorly to a local electric induction field and very well to a magnetic one. An electrically small dipole would be just the opposite in response to induction fields. This is theoretically and empirically correct. I have much experience using these types of antennas monitoring for induction fields and they behaved as theory predicted. When poorly designed electronic devices generate induction fields the electric fields have the tendency to spread farther from the source than the magnetic fields. This is a generalization but knowing this leads to the conclusion that a loop would pick up less of the locally generated noise most of the time or in other words it would be an advantage to use over a dipole. Most people that have local noise problems and purchase a loop antenna such as the Wellbrook find that their listening situation is greatly improved. I use a non-amplified folded dipole and non-amplified shielded loop. The loop picks up much less of the local noise and picks up as much signal as the folded dipole depending on the band. Notice that belief is not required for any of the foregoing. ************ You have the right idea about field impedance vs distance but that relationship is appropriate for transmitting antennas that are efficient. Here the subject is inefficient noise sources. Here the induction fields fall off rapidly compared to an efficient antenna. ************* I just noticed that your ALA 100 is pretty big and not electrically small at SW frequencies. This means it will also respond to electric fields and being broadband will raise the noise floor. Your 60 foot amplified loop is 10 feet bigger than my passive loop. Why do you need an amplifier with a 60 foot loop? Normally when I consider an amplified loop it more like 1 to 3 foot in diameter. Here again, I believe being broadband increases the integrated noise, but not necessarily the noise measured per root Hz. The final bandwidth of the filter of the radio determines the integrated noise. Say the noise was 1nV/root Hz. Say the filter bandwidth was 6Khz. Multiply the square root of 6Khz times 1nV/Root Hz to get 77.5nV. That's why even if I know the model number of the spectrum analyzer I can not easily know the instrument noise floor in the sweep. The sweep settings will modify the noise floor. I took another look at the measurement pdf and I think it likely that the analyzer noise floor at those settings is lower than the measurement noise in the sweeps and so at least in the last pair of comparison photos on page 3 clearly show that the ALA-100 has a poorer signal to noise than the vertical he is comparing it with. I still don't know about the other sweeps as I don't know what is a radio station and what is the local noise in the sweep. When I did work on a range I would turn the DUT on and off to see what actually popped up on the sweep when the DUT is turned on. You had to do this on a range where you can't have a large enough screen room due to cost. I'm sure the author knows what is being generated by the stuff in his house and what is a radio station. It looks to me that although the Wellbrook amplifiers have very good intermodulation numbers but that the noise floor may be high. You would have to put in a larger signal into the Wellbrook to measure the intermodulation products relative to the other antenna amplifiers in the pdf document. Wellbrook does not appear to give a noise figure for the amplifier. The author of the pdf could easily make that measurement since he has an analyzer. Maybe noise is coming in through the power supply connection for the amplifier, the amplifier has a poor noise floor, or the antenna is picking it up. The difficulty in making measurements on the ALA 100 with test instruments is you need a differential drive. I don't know if grounding one side is kosher. Grounding one side would not be acceptable. I would use a simple test BALUN to drive the input. -- Telamon Ventura, California Yeah, but then what are you testing. The ALA 100 or the balun. Good instrumentation isn't simple. The BALUN would be simple and you would test it first. It would be no problem at all. -- Telamon Ventura, California Not really. You need the balun to "act" like the wire antenna, which means you need to characterize the wire antenna first, so you know the impedance you need for each frequency tested. There is a reason why Welbrook has no competition. I wish they did since that would lower the price of the gear. I'm sure ANdy Ikin is just snickering at this thread. |
Vertical Antenna And ALA 100 Comparisons
Hi Dallas,
I've been curious about your noise-reducing antennas some time, so this past weekend I decided to build one as accurately as possible per your design. I first got interested these antennas in the early 1990s during some e-mail exchanges with Denzil Wraight in Germany. I used the 3:1 turns ratio in the antenna transformer, and 18 ga. twinlead speakerwire between it and the 1:1 transformer. The top of the 45 ft. vertical is suspended to a branch in a tall tree, and the bottom end fastened to a 5-ft. copper pipe in the ground. The antenna is located about 60 feet from the house, and my Wellbrook ALA 100 is 40 feet from the house. I was quite surprised find not just worse noise from the vertical, but MUCH worse noise. Signal levels seem good, but the noise is so bad the readability suffers greatly, compared to the loop. For instance, this morning past sunrise I was hearing JOAK in Tokyo on 594 kHz with an S-3 signal in Japanese, coming in nicely on the loop. However, the same frequency on the vertical was just a strong BUZZZZZ of light-dimmer type QRM. This was the most pronounced of the comparisons, but in most cases of checking frequencies up through HF, the loop was the outright winner. I tried to record 594 khz for comparisons, but I was using my modded R-75 and didn't have the recording software configured properly since my last DXpedition, and my SDR-1000 isn't fully hooked up at the moment. So, I wasn't able to make a quick recording before the signal faded with increasing daylight. I did find a couple signals on the tropical bands where the vertical provided a stronger signal with equal noise pickup (so therefore better S/N than the loop). However, my main interest right now is foreign MW signals. Do you have any tips for improving this antenna's noise rejection on MW? I can only think of two things that might impact the performance here. I used the same type of binocular core ferrites that W8JI recommends, as I have a lot of them. You used a traditional torroid form. Also, I don't know how good the ground needs to be for this antenna to work well; the single 5-ft pipe may not be sufficient (soil here is reasonably good, though, clay mixed with organic material...it's a forest floor). Thanks in advance for any ideas! Guy Atkins Puyallup, WA www.sdr-1000.blogspot.com "R390A" wrote in message ps.com... Oops. It should be www.kongsfjord.no R390A wrote: To Whom It May Concern: Additions and revisions have been made to two of my articles about vertical antennas and the ALA 100 on the www.kongsfjord.com web site. The articles are (1) "Measurements Of Some Antennas Signal To Man Made Noise Ratios In The Daytime MW And LW Bands," and (2) "Some Of My Favorite Small Antennas For MW And LW." In the first article an additional comparison of the ALA 100 was made with an active whip antenna. The ALA 100 and active whip had about the same signal to man made noise ratio. In the second article some information was added about reducing noise in active whip antennas due to what are believed to be ground loops in the DC feed. |
Vertical Antenna And ALA 100 Comparisons
Do the Horizontal Antenna Bump.I reckon I will go and check out
alt.military.police news group now.Then I might go and check out that alt.scooter news group thingy too. cuhulin |
Vertical Antenna And ALA 100 Comparisons
She Will Be Coming Around The Mountain when She Comes,,,,, Grapes of
Wrath. cuhulin |
Vertical Antenna And ALA 100 Comparisons
Telamon,it took me ten years to scroll down to what you were saying.You
need to work on that. cuhulin |
Vertical Antenna And ALA 100 Comparisons
|
Vertical Antenna And ALA 100 Comparisons
In article . com,
wrote: Telamon wrote: In article . com, wrote: Telamon wrote: In article . com, wrote: Telamon wrote: In article . com, wrote: Telamon wrote: In article .com, "R390A" wrote: Telamon wrote: In article .c om, "R390A" wrote: To Whom It May Concern: Additions and revisions have been made to two of my articles about vertical antennas and the ALA 100 on the www.kongsfjord.com web site. The articles are (1) "Measurements Of Some Antennas Signal To Man Made Noise Ratios In The Daytime MW And LW Bands," and (2) "Some Of My Favorite Small Antennas For MW And LW." In the first article an additional comparison of the ALA 100 was made with an active whip antenna. The ALA 100 and active whip had about the same signal to man made noise ratio. In the second article some information was added about reducing noise in active whip antennas due to what are believed to be ground loops in the DC feed. The link is dead. http://www.kongsfjord.no/dl/Antennas/Measurements%2 0Of%20So me%2 0Antenna s %20Signal%20To%20Man%20Made%20Noise%20Ratio.pdf Try www.kongsfjord.no and then click on The Dallas Files. That link worked. Looking at your data I'm at a disadvantage not knowing which are radio stations and which are computer noise other than KNOE 540 kHz you specifically pointed out. Another problem for me is the loop antenna gain looks to be about 10 dB less than the other antennas. While actually not a problem for signal to noise measurements it does make the sweep look different to a person that did not make the measurement. Antennas in different locations around your house is not exactly apples to apples comparison. If your spectrum analyzer has a max hold on the trace that would be a help in measuring the top of the noise floor. A clear difference in S/N would be the last pair on page three 1500 to 2000 KHz where the ALA-100 looks to be 22 dB (-42 S to -60 N) compared to the vertical 33 dB (-32 S to -65 N). One problem for me here is I don't know what the analyzer noise floor itself is at this point and I can see that the loop has 10 dB less gain than the other antennas. Assuming that the analyzer noise floor is -70 dBm and lower would make this comparison valid. A simple check of just disconnecting the cable from the analyzer at those settings would show the instrument noise floor. Using max hold would make the noise floor less ambiguous. Due to my disadvantages noted I can't draw any firm conclusions based on the analyzer pictures. I'm an audio person, but noise should be measured in terms of root hertz. Thus the noise floor you see is a function of the bandwidth of the tracking filter. As you go narrower, the noise floor should drop. ************* I have to take exception to the wording you ascribe to other people such as myself about a "belief in magnetic field sensitive antennas". I rely on belief only when I have no other choice as a fall back to no being able to test a thesis empirically. An electrically small shielded loop antenna will respond very poorly to a local electric induction field and very well to a magnetic one. An electrically small dipole would be just the opposite in response to induction fields. This is theoretically and empirically correct. I have much experience using these types of antennas monitoring for induction fields and they behaved as theory predicted. When poorly designed electronic devices generate induction fields the electric fields have the tendency to spread farther from the source than the magnetic fields. This is a generalization but knowing this leads to the conclusion that a loop would pick up less of the locally generated noise most of the time or in other words it would be an advantage to use over a dipole. Most people that have local noise problems and purchase a loop antenna such as the Wellbrook find that their listening situation is greatly improved. I use a non-amplified folded dipole and non-amplified shielded loop. The loop picks up much less of the local noise and picks up as much signal as the folded dipole depending on the band. Notice that belief is not required for any of the foregoing. ************ You have the right idea about field impedance vs distance but that relationship is appropriate for transmitting antennas that are efficient. Here the subject is inefficient noise sources. Here the induction fields fall off rapidly compared to an efficient antenna. ************* I just noticed that your ALA 100 is pretty big and not electrically small at SW frequencies. This means it will also respond to electric fields and being broadband will raise the noise floor. Your 60 foot amplified loop is 10 feet bigger than my passive loop. Why do you need an amplifier with a 60 foot loop? Normally when I consider an amplified loop it more like 1 to 3 foot in diameter. Here again, I believe being broadband increases the integrated noise, but not necessarily the noise measured per root Hz. The final bandwidth of the filter of the radio determines the integrated noise. Say the noise was 1nV/root Hz. Say the filter bandwidth was 6Khz. Multiply the square root of 6Khz times 1nV/Root Hz to get 77.5nV. That's why even if I know the model number of the spectrum analyzer I can not easily know the instrument noise floor in the sweep. The sweep settings will modify the noise floor. I took another look at the measurement pdf and I think it likely that the analyzer noise floor at those settings is lower than the measurement noise in the sweeps and so at least in the last pair of comparison photos on page 3 clearly show that the ALA-100 has a poorer signal to noise than the vertical he is comparing it with. I still don't know about the other sweeps as I don't know what is a radio station and what is the local noise in the sweep. When I did work on a range I would turn the DUT on and off to see what actually popped up on the sweep when the DUT is turned on. You had to do this on a range where you can't have a large enough screen room due to cost. I'm sure the author knows what is being generated by the stuff in his house and what is a radio station. It looks to me that although the Wellbrook amplifiers have very good intermodulation numbers but that the noise floor may be high. You would have to put in a larger signal into the Wellbrook to measure the intermodulation products relative to the other antenna amplifiers in the pdf document. Wellbrook does not appear to give a noise figure for the amplifier. The author of the pdf could easily make that measurement since he has an analyzer. Maybe noise is coming in through the power supply connection for the amplifier, the amplifier has a poor noise floor, or the antenna is picking it up. The difficulty in making measurements on the ALA 100 with test instruments is you need a differential drive. I don't know if grounding one side is kosher. Grounding one side would not be acceptable. I would use a simple test BALUN to drive the input. -- Telamon Ventura, California Yeah, but then what are you testing. The ALA 100 or the balun. Good instrumentation isn't simple. The BALUN would be simple and you would test it first. It would be no problem at all. -- Telamon Ventura, California Not really. You need the balun to "act" like the wire antenna, which means you need to characterize the wire antenna first, so you know the impedance you need for each frequency tested. There is a reason why Welbrook has no competition. I wish they did since that would lower the price of the gear. I'm sure ANdy Ikin is just snickering at this thread. No you do not want the BALUN to "act" like the antenna wire. The BALUN is to couple the generators single ended output to the differential amplifier input so the amplifier can be tested. This is trivial thing to do to test the amplifier. I'm not going to argue about this. Amplified loop outdoor antennas have a number of costs associated with them and I don't expect prices to lower. -- Telamon Ventura, California |
Vertical Antenna And ALA 100 Comparisons
My webtv hand held remote control thangy and my webtv keyboard thangy
has two (count em,two) scroll functions.Slow and Fast.My webtv scrolls can scroll up and down just as fast (maybe even Faster) as your puter can. cuhulin |
Vertical Antenna And ALA 100 Comparisons
I can leave you sittin at the Post.
cuhulin |
Vertical Antenna And ALA 100 Comparisons
Guy Atkins wrote: Hi Dallas, I've been curious about your noise-reducing antennas some time, so this past weekend I decided to build one as accurately as possible per your design. I first got interested these antennas in the early 1990s during some e-mail exchanges with Denzil Wraight in Germany. I used the 3:1 turns ratio in the antenna transformer, and 18 ga. twinlead speakerwire between it and the 1:1 transformer. The top of the 45 ft. vertical is suspended to a branch in a tall tree, and the bottom end fastened to a 5-ft. copper pipe in the ground. The antenna is located about 60 feet from the house, and my Wellbrook ALA 100 is 40 feet from the house. I was quite surprised find not just worse noise from the vertical, but MUCH worse noise. Signal levels seem good, but the noise is so bad the readability suffers greatly, compared to the loop. For instance, this morning past sunrise I was hearing JOAK in Tokyo on 594 kHz with an S-3 signal in Japanese, coming in nicely on the loop. However, the same frequency on the vertical was just a strong BUZZZZZ of light-dimmer type QRM. This was the most pronounced of the comparisons, but in most cases of checking frequencies up through HF, the loop was the outright winner. I tried to record 594 khz for comparisons, but I was using my modded R-75 and didn't have the recording software configured properly since my last DXpedition, and my SDR-1000 isn't fully hooked up at the moment. So, I wasn't able to make a quick recording before the signal faded with increasing daylight. I did find a couple signals on the tropical bands where the vertical provided a stronger signal with equal noise pickup (so therefore better S/N than the loop). However, my main interest right now is foreign MW signals. Do you have any tips for improving this antenna's noise rejection on MW? I can only think of two things that might impact the performance here. I used the same type of binocular core ferrites that W8JI recommends, as I have a lot of them. You used a traditional torroid form. Also, I don't know how good the ground needs to be for this antenna to work well; the single 5-ft pipe may not be sufficient (soil here is reasonably good, though, clay mixed with organic material...it's a forest floor). Thanks in advance for any ideas! Guy Atkins Puyallup, WA www.sdr-1000.blogspot.com I have found that a single ground point,ie "standard" 8' AC mains ground ro, are at best very marginal. And the lower the frequency, as a general rule, the "bigger" the ground should be. Hams often use radials. Think of the classic dipole. It has two arms. The classic vertical "monopole" needs a very good, ie low RF resistance, grounds. At the very least I would try for a set of 3 6' ground rods seperated from each other by at least 6'. I think I may have gone overboard with a whole house perimeter ground ring, but I was given the copper tubing and a friend used a small Ditch Witch to dig the trench. Did the improved ground make a difference over the discribed set of 3 rods? There is a 10W TIS station in Winchester that I couldn't receive on my 70' "long" wire antenna with a R2000. I tried a, as near as I could build it, identical ground set up and wire antenna at about the same height, from a friend's home who is about 5 miles closer and who has a lower RF background noise floor and I think I could detect the carrier in SSB. Maybe your soil is unusualy conductive and a 5' rod will suffice, but I suspect that a better, ie more complete, ground system will help all of your non dipole antennas. And exception to the "good" set of 3 ground rod "rule" is with the Lankford Active Antenna, AKA AMRAD, which will operate very nicely on a single 8' ground rod driven so that 2' remain above ground for a mounting base. With a Lankford Active Dipole no ground is required. I have tried one with and without the 6'/2' ground rod. And it worked very well both ways. At some frequencies the grounded operation was a little quiter. Of course with any active antenna great care should be taken to insure that common noise mode noise doesn't go up the braid and enter the antenna. The Dipole configeration is much less sensitive to common mode, but it attention to detail will be rewarded. The best single refference I have found is the "Common Mode Choke" PDF by W1HIS. I don't have the link handy, but I have given the link several times. A call to your local utility and/or a MW broadcaster can often get you valid information on local ground conductivity conditions. I did notice that on the coldest days last winter, when the temp droped to below 0F, where my older ground lost some effficeincy from the ground freezing, my new, super ground never varried. And this summer during the drier, though to be fair this was hardly a dry summer, periods my ground stayed effective. I am not really into NDB or MW DX but I can report that the improved ground really made a lot more NDBs receivable, and I found a lot more garbage stations on MW. A simpler super ground that we installed for Will, a new SWL that I am helping, consisted of a 1/4" copper tube that is about 20' long and connects his "SW" ground to the AC/Mains/Telco/SatDish ground. Lowered his noise by several S-units on a DX398 all across LW/MW and lower SW bands. He used a funky flat shovel to open a slot about 6" deep. I would have prefered deeper, but it was his home, copper and effort. Terry |
Vertical Antenna And ALA 100 Comparisons
Hi Terry,
I tried a 4-foot ground rod because that's what Dallas showed in the antenna diagram for his article. I do see now that his older article (which he reproduces as an addendum to the newer version) shows and describes an 8-foot ground rod, however. I have a Bentonite-enhanced ground rod about 12 feet away from the 4-footer. I previously to use it for grounding the shield of a EWE antenna feedline, but it's not currently in use, so I might run a heavy wire to that one and give it a try. It's a good ground, and I've always had success with Bentonite enhancement. It's such a hassle to dig the larger hole to hold all the powdered Bentonite and water slurry, but the results can be worth the effort. In Seattle I've bought 50 lbs. of Bentonite for for just $13, but that was a few years ago. I used to get all I wanted for free, as my wife's home town in Wyoming has a number of Bentonite processing plants in the area. They would give away slightly ripped bags of the stuff to anyone crazy enough to ask for it! Guy wrote in message ups.com... I have found that a single ground point,ie "standard" 8' AC mains ground ro, are at best very marginal. And the lower the frequency, as a general rule, the "bigger" the ground should be. Hams often use radials. SNIP Terry |
Vertical Antenna And ALA 100 Comparisons
Guy Atkins wrote: Hi Terry, I tried a 4-foot ground rod because that's what Dallas showed in the antenna diagram for his article. I do see now that his older article (which he reproduces as an addendum to the newer version) shows and describes an 8-foot ground rod, however. I have a Bentonite-enhanced ground rod about 12 feet away from the 4-footer. I previously to use it for grounding the shield of a EWE antenna feedline, but it's not currently in use, so I might run a heavy wire to that one and give it a try. It's a good ground, and I've always had success with Bentonite enhancement. It's such a hassle to dig the larger hole to hold all the powdered Bentonite and water slurry, but the results can be worth the effort. In Seattle I've bought 50 lbs. of Bentonite for for just $13, but that was a few years ago. I used to get all I wanted for free, as my wife's home town in Wyoming has a number of Bentonite processing plants in the area. They would give away slightly ripped bags of the stuff to anyone crazy enough to ask for it! Guy Before I went completly nuts and put the perimenter ground ring in , I used clumping kitty litter, which uses a bentonite and baked/ground clay mixture. I poured the kitty litter in to a depth of several inches and added water and repeated until it was up to 5 or 6" fro the surface. I also had a capped 1" PVC pipe with holes drilled every inch or so that during realy dry summers I would route filtered grey water from the washing machine. The ground ring is significantly better as in lower over all noise floor, especially for VLF/whistler reception. The hardest part was convincing the telephone company to use my ground. They wanted to use a diky 4' ground rod. Altel oh ya. Two cans on a string would work as well. Terry |
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