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antenna matching ??
I need a sanity check. I fellow told me he was getting a balun to get a
better match between his receiver and antenna to get a better signal to noise ratio. I told him he was wasting his time and money because a better match increases transfer of both signal and noise. But since he already can hear the signal he doesn't need any more. Now if he was to get a more directional antenna he would get a reduction in noise from the undesired direction. -- 73 Hank WD5JFR |
"Henry Kolesnik" wrote in message m... I need a sanity check. I fellow told me he was getting a balun to get a better match between his receiver and antenna to get a better signal to noise ratio. I told him he was wasting his time and money because a better match increases transfer of both signal and noise. But since he already can hear the signal he doesn't need any more. Now if he was to get a more directional antenna he would get a reduction in noise from the undesired direction. -- 73 Hank WD5JFR Your sanity's fine Hank. But why hurt the Balun manufacturer's business for the sake of an argument to no good purpose? Just tell this fellow that Radio Works (Portsmouth Va) will be happy to ship him a well made 4:1 Balun on the day of or day following his order. That helps keep a good company in business and it won't hurt your fellow's reception any. Jack |
On Fri, 15 Apr 2005 13:48:15 GMT, "Henry Kolesnik"
wrote: I need a sanity check. I fellow told me he was getting a balun to get a better match between his receiver and antenna to get a better signal to noise ratio. I told him he was wasting his time and money because a better match increases transfer of both signal and noise. But since he already can hear the signal he doesn't need any more. Now if he was to get a more directional antenna he would get a reduction in noise from the undesired direction. Generally true if the external noise dominates the internally generated receiver noise. This is the usual case in the hf region. At vhf it is normally not so. Improvements in antenna gain (directivity) and matching and reduction of transmission line loss all can improve vhf SNR. A balun *might* improve SNR at hf if the "feedline antenna" is more susceptible to locally generated noise than the "real antenna" is. |
Hank, WD5JFR wrote:
"Now if he was yto get a more directional antenna he would get a reduction in noise from the undesired direction." A balun which reduces pickup ftom a nondirectional transmission line may reduce noise too. Best regards, Richard Harrison, KB5WZI |
Henry Kolesnik wrote:
I need a sanity check. I fellow told me he was getting a balun to get a better match between his receiver and antenna to get a better signal to noise ratio. I told him he was wasting his time and money because a better match increases transfer of both signal and noise. But since he already can hear the signal he doesn't need any more. Now if he was to get a more directional antenna he would get a reduction in noise from the undesired direction. I ran a test at my QTH with my horizontal dipole fed with vertical ladder-line. I removed the balun-choke at the coax to ladder-line junction. The noise level went up by almost one S-unit. I suspect the culprit is localized vertically polarized power line noise that has thwarted my every attempt to use a vertical on 40m at my QTH. -- 73, Cecil, W5DXP ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Wes Stewart wrote:
A balun *might* improve SNR at hf if the "feedline antenna" is more susceptible to locally generated noise than the "real antenna" is. That's apparently the case at my QTH, Wes. The localized vertically polarized power line noise was about two S-units on my 40m vertical attempt which rendered it useless for weak signal DX purposes. -- 73, Cecil, W5DXP ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Cecil
Did the noise go up one S unit and the desired signal stay the same? -- 73 Hank WD5JFR "Cecil Moore" wrote in message ... Henry Kolesnik wrote: I need a sanity check. I fellow told me he was getting a balun to get a better match between his receiver and antenna to get a better signal to noise ratio. I told him he was wasting his time and money because a better match increases transfer of both signal and noise. But since he already can hear the signal he doesn't need any more. Now if he was to get a more directional antenna he would get a reduction in noise from the undesired direction. I ran a test at my QTH with my horizontal dipole fed with vertical ladder-line. I removed the balun-choke at the coax to ladder-line junction. The noise level went up by almost one S-unit. I suspect the culprit is localized vertically polarized power line noise that has thwarted my every attempt to use a vertical on 40m at my QTH. -- 73, Cecil, W5DXP ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Henry Kolesnik wrote:
Did the noise go up one S unit and the desired signal stay the same? There was no signal present when I tried it. I'll perform it again with a signal present. I don't know what it will show if the signal is S-6 and the noise level goes from S-3 to S-4. -- 73, Cecil, W5DXP ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
I could be mistaken, however, I think the radiation patten (and receive
patten) would, at least, be slightly affected by a mis-match... whether this would justify going to extreme means of correction is debatable... Regards, John "Henry Kolesnik" wrote in message m... I need a sanity check. I fellow told me he was getting a balun to get a better match between his receiver and antenna to get a better signal to noise ratio. I told him he was wasting his time and money because a better match increases transfer of both signal and noise. But since he already can hear the signal he doesn't need any more. Now if he was to get a more directional antenna he would get a reduction in noise from the undesired direction. -- 73 Hank WD5JFR |
How does a mismatch affect the radiation pattern?
tnx -- 73 Hank WD5JFR "John Smith" wrote in message ... I could be mistaken, however, I think the radiation patten (and receive patten) would, at least, be slightly affected by a mis-match... whether this would justify going to extreme means of correction is debatable... Regards, John "Henry Kolesnik" wrote in message m... I need a sanity check. I fellow told me he was getting a balun to get a better match between his receiver and antenna to get a better signal to noise ratio. I told him he was wasting his time and money because a better match increases transfer of both signal and noise. But since he already can hear the signal he doesn't need any more. Now if he was to get a more directional antenna he would get a reduction in noise from the undesired direction. -- 73 Hank WD5JFR |
Because it is dependent on any "lumped" inductive or capacitive reactances
present... chuck a coil or capacitance (reactance) in the structure of the antenna, then replot with a field strength meter... Regards, John "Henry Kolesnik" wrote in message ... How does a mismatch affect the radiation pattern? tnx -- 73 Hank WD5JFR "John Smith" wrote in message ... I could be mistaken, however, I think the radiation patten (and receive patten) would, at least, be slightly affected by a mis-match... whether this would justify going to extreme means of correction is debatable... Regards, John "Henry Kolesnik" wrote in message m... I need a sanity check. I fellow told me he was getting a balun to get a better match between his receiver and antenna to get a better signal to noise ratio. I told him he was wasting his time and money because a better match increases transfer of both signal and noise. But since he already can hear the signal he doesn't need any more. Now if he was to get a more directional antenna he would get a reduction in noise from the undesired direction. -- 73 Hank WD5JFR |
Henry Kolesnik wrote:
How does a mismatch affect the radiation pattern? Please define "mismatch". An unbalanced 50 ohms to balanced 50 ohms could conceivably be defined as a "mismatch". -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
"John Smith" said - I could be mistaken, however, I think the radiation patten (and receive patten) would, at least, be slightly affected by a mis-match... whether this would justify going to extreme means of correction is debatable... ============================== John, your level of analysis is far, far above that justified by the simplicity of the problem(s). Just get some wire in the air and see how well it works. ---- Reg, G4FGQ |
LOL! Sometimes I forget Reg--sorry grin
Warmest regards, John "Reg Edwards" wrote in message ... "John Smith" said - I could be mistaken, however, I think the radiation patten (and receive patten) would, at least, be slightly affected by a mis-match... whether this would justify going to extreme means of correction is debatable... ============================== John, your level of analysis is far, far above that justified by the simplicity of the problem(s). Just get some wire in the air and see how well it works. ---- Reg, G4FGQ |
How does a mismatch affect the radiation pattern?
tnx ..... It doesn't. I don't consider unbalanced, the same as mismatched, to answer Cecils question. Feedline radiation can effect the pattern due to a lack of balun, etc, but thats not the same thing as an impedance mismatch. Also...Antenna "loading" is not the same as antenna "matching". Many short verticals need both... MK |
Maybe I have a misunderstanding. I see a "mismatch" as being caused by only
two factors, either an uncompensated reactance--or, as Cecil mentioned, feeding a bal/unbal antenna with the wrong feedline. Indeed, any feedline can simply be analyzed as a series of lumped reactances--inductive and capactitive. How should I be viewing this? Regards, John wrote in message oups.com... How does a mismatch affect the radiation pattern? tnx ..... It doesn't. I don't consider unbalanced, the same as mismatched, to answer Cecils question. Feedline radiation can effect the pattern due to a lack of balun, etc, but thats not the same thing as an impedance mismatch. Also...Antenna "loading" is not the same as antenna "matching". Many short verticals need both... MK |
Errr, let me be a bit more specific...
The "beam width" of a quarter-wave has a very wide "acceptance ratio" and grabs much more reflection from the ionosphere--a half-wave has a much narrower beam width--it is a "quieter" antenna, but, grabs more of the signal I am after... At least, it appears like that... A five-eights-wave has even a lower beam width--these three antennas, because of length differences, exhibit differing reactances, when these reactances are cancelled (such as using an L-Match) they become "matched"--right? Of course, this ignores conductor resistance, and takes for granted the antenna is being fed at the proper point... Regards, John "John Smith" wrote in message ... Maybe I have a misunderstanding. I see a "mismatch" as being caused by only two factors, either an uncompensated reactance--or, as Cecil mentioned, feeding a bal/unbal antenna with the wrong feedline. Indeed, any feedline can simply be analyzed as a series of lumped reactances--inductive and capactitive. How should I be viewing this? Regards, John wrote in message oups.com... How does a mismatch affect the radiation pattern? tnx ..... It doesn't. I don't consider unbalanced, the same as mismatched, to answer Cecils question. Feedline radiation can effect the pattern due to a lack of balun, etc, but thats not the same thing as an impedance mismatch. Also...Antenna "loading" is not the same as antenna "matching". Many short verticals need both... MK |
"John Smith" wrote
The "beam width" of a quarter-wave has a very wide "acceptance ratio" and grabs much more reflection from the ionosphere--a half-wave has a much narrower beam width--it is a "quieter" antenna, but, grabs more of the signal I am after... _____________ A 1/2-wave VHF/UHF vertical has more gain at lower elevation angles than a 1/4-wave, but that may not usefully improve the SNR of the system. Most of the noise power in these antennas doesn't arrive from higher angles anyway, because those freqs don't reflect well from the ionosphere. RF |
No. Feeder radiation has *nothing* to do with impedance
matching. Zero. Nada...Zilch. Ever!...You can have a perfect 1:1 match, and still have feedline radiation. Or you can have a horrible impedance mismatch, and have very little feeder radiation. Feeder unbalance, lack of baluns, chokes, etc, etc, should never be confused with impedance matching. I don't think the term "mismatch" should be applied to a lack of balance, etc...If you tell me you have a mismatch, I'll always assume you mean impedance. Anyway, no matter my views... Impedance mismatch will never change the pattern of the antenna. For practical purposes, it's the same as raising or lowering power to the antenna. If you run 50 more watts to an antenna, it's pattern does not change. Ditto, if you run 50 less...MK |
huh? If you have an impedance mismatch, you are NOT feeding the antenna at
the proper point, or with the proper ohm line, or without a proper matching circuit! Either one of these will exhibit some type of reactance! OR! OMG! My "knowledge"/thinking is in error! ???? Regards, John wrote in message ups.com... No. Feeder radiation has *nothing* to do with impedance matching. Zero. Nada...Zilch. Ever!...You can have a perfect 1:1 match, and still have feedline radiation. Or you can have a horrible impedance mismatch, and have very little feeder radiation. Feeder unbalance, lack of baluns, chokes, etc, etc, should never be confused with impedance matching. I don't think the term "mismatch" should be applied to a lack of balance, etc...If you tell me you have a mismatch, I'll always assume you mean impedance. Anyway, no matter my views... Impedance mismatch will never change the pattern of the antenna. For practical purposes, it's the same as raising or lowering power to the antenna. If you run 50 more watts to an antenna, it's pattern does not change. Ditto, if you run 50 less...MK |
wrote:
No. Feeder radiation has *nothing* to do with impedance matching. Note Webster's has a different definition of mismatch than the IEEE Dictionary. That's why I asked for a definition. For instance, going from a black coax to an orange coax could be called a color "mismatch". -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
A two conductor transmission line, with Earth or other conductors
providing a potential third conductor, has two defined impedances. One convenient and intuitive way of defining these two is as common-mode and differential-mode (or even and odd mode) impedances. Our measurement equipment invariably measures the differential (odd) mode impedance, so when we speak of impedance "matching" or "mismatch" we virtually always mean matching of differential mode impedance. Differential mode currents don't contribute to radiation. Differential mode impedance match or mismatch has no effect at all on antenna pattern. It can have an indirect effect on antenna *system* performance due to potential losses in impedance matching components. But otherwise the quality of impedance match can be ignored when considering antenna performance. Common mode current radiates, so a transmission line carrying common mode current (a twinlead line with imbalanced currents, or a coax line with current on the outside of the shield) is actually part of the antenna. Anything which alters the current flow or distribution of this current (for example, a current balun) will alter the overall radiation pattern. If a transmission line is perfectly balanced, the common mode current is zero, and the term "match" or "mismatch" can't be meaningfully applied to the common mode impedance. Roy Lewallen, W7EL Cecil Moore wrote: wrote: No. Feeder radiation has *nothing* to do with impedance matching. Note Webster's has a different definition of mismatch than the IEEE Dictionary. That's why I asked for a definition. For instance, going from a black coax to an orange coax could be called a color "mismatch". |
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