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Noise Reducing Antennas
John Doty's noise reducing antenna ideas from his 1993 posting are virtually
identical to noise reducimg antenna ideas found in articles by Denzil Wraight and me which were published in DX News in 1991. Denzil's article was titled "Interference Reducing Antennas For The BCB," and mine was "Inverted L Noise Reducing MF/VLF Antenna." Denzil and I used twinlead rather than coax. However, Mark Connelly published descriptions of similar noise reducinmg antennas using coax in DX News later in 1991. These articles are available from The National Radio Club http://www.nrcdxas.org/ as reprint A69. Contrary to what John claims, these kinds of noise reducing antennas are not very effective against noise at SW frequencies much above 6 MHz. These types of noise reducing antennas were invented by F. R. W. Strafford in or about 1936, and he discusses these and other types of noise reducing antennas for short waves in "Screened Aerials," Wireless World, November 25, 1937, pages 516 - 518. Best regards, Dallas |
DALLAS {aka: AEN} ,
Long ago John Doty corrected me on the 'fact' that he did not "Invent" these Antennas or the Design Concepts of these Low Noise Antennas. However, within this Forum {Rec.Radio.Shortwave} his 'articles' {Writings} and his 'name' are/is the most often cited reference concerning this topic. This is why I say {write} "Low Noise SWL Antenna" using the 'design concepts' that were popularized by John Doty. READ - Three "Must" Links to Read -wrt- Low Noise SWL Antenna http://groups.yahoo.com/group/Shortw...na/message/949 NOTE: John Doty's 'articles' {Writings} and his 'name' are/is available freely on the Web (WWW) and thus Millions may View and Read them. AEN - ? Have you consider 're-printing' your 'articles' {Writings} on the Web (WWW) and making them Free for All to View and Read ? AEN - Doing so, may provide you with the recognition that you so justly deserve. TBL: As to whether, the "Low Noise" Antenna 'design concepts' work well for Shortwave Listener (SWL) Antennas: They have improved my Shortwave Listening with good signal levels and much lower noise. What more can I say: "I Ain't No Elmer !" Enjoy Listening to your Radio/Receivers with your Antennas. iane ~ RHF .. All are WELCOME at the Shortwave Listener (SWL) "Antenna Ashram" http://groups.yahoo.com/group/Shortw...na/message/502 Some Say: On A Clear Day You Can See Forever. I BELIEVE: On A Clear Night . . . You Can Hear Forever and Beyond, The BEYOND ! [ With the a SWL Antenna of your own making. ] .. .. |
Hi whatever your name is,
I am puzzled. If, as you wrote, John corrected you on the 'fact' that he did not "Invent" these Antennas or the Design Concepts of these Low Noise Antennas, then presumably he told you who did. So why have he and you neglected to mention that in your writings? It was Denzil Wraight, in fact, who rediscovered Strafford's work on noise reducing antennas, and who discovered by trial and error reasonable turns ratios for the antenna matching transformers (Strafford does not discuss that in his articles). So it is Strafford and Wraight that Doty plagiarized and you failed to cite. Denzil used a vertical noise reducing antenna, wrote me about how well it worked, and included a copy of Strafford's Wireless World article. First I constructed a "top fed" vertical version with mast almost touching my house. I didn't expect it to do much fow man made noise in the MW band (my main interest), but to my surprise it did. In my case, there was little, if any, difference noise reduction between mounting the vertical mast almost touching my house, or 100 feet away. So this kind of noise reducing antenna is ideal for DXers with limited space. Next I implemented an inverted L version of Strafford's noise reducing antennas. If I recall correctly, the first L was about 100 feet horizontal and 15 feet vertical. I experimented with both base feed and top feed. Both gave excellent noise reduction in the MW (and VLF) band(s). Both Denzil and I used twin feed instead of coax because twin feed tends to pick up less local nois than coax. Denzil and I wrote two separate articles for DX news (The National Radio Club http://www.nrcdxas.org/ reprint A69) that were published in the early summer of 1991. I had sent Mark Connelly preprints of our arfticles, and he developed coax feed versions of Strafford's noise reducing antennas. According to Mark, the coax feed variant picked up little, if any additional noise compared to the twin feed version. At one point in these experiments I tried shielded twin lead, but found no further noise reduction (or increase). Presently I use top fed inverted L noise reducing antennas as parts of my phased arrays. Unless you are listening above 16 MHz or so, or have an insensitive receiver, you don't really need (or want) a big inverted L. Mine are 15 feet up and 30 feet horizontal. The matching transformer we used then (and which I still use now) is an Amidon FT-114-75 (the 75 material may have been replaced with J material), 43 turns to 9 turns (at the center of the 43 turns) #20 enameled copper wire. The twin lead I still use is Radio Shack speaker wire (#18 stranded, 7 strands of, I think, #26). It is cheaper ane easier to use than real twin lead, and had about the right characteristic impedance (about 100 ohms). You'll need a balun (1:1) at your receiver to convert the balanced lead in to your unbalanced receiver antenna input (9 bifilar turns of #20 enameled on an FT-114-75 will do). Like I said before, the noise reducing properties of these kinds of antennas begin to decline as you go higher in frequency, and above 6 MHz there is not much noise reduction. If you believe you got substantial noise reduction above 6 MHz due only to using one of these kinds of antennas, then you are mistaken. For SW, Strafford recommended doublet antennas for noise reduction. I do not have much experience with these because I am not much of a SW listener. What little experience I have suggests that phased arrays are much more effective at reducing SW noise sources. Unfortunately,there are no good phasers that you can buy. As for publishing these articles on the web, that would involve considerable work. The articles were produced with typewriters, and contain hand drawings. To convert them to .PDF or other files would be non-trivial, and would require NRC approval. Anyone who wants these articles can easily purchase them as reprints from the NRC at the web site above using PayPal or other methods of payment. Best regards, Dallas "RHF" wrote in message oups.com... DALLAS {aka: AEN} , Long ago John Doty corrected me on the 'fact' that he did not "Invent" these Antennas or the Design Concepts of these Low Noise Antennas. However, within this Forum {Rec.Radio.Shortwave} his 'articles' {Writings} and his 'name' are/is the most often cited reference concerning this topic. This is why I say {write} "Low Noise SWL Antenna" using the 'design concepts' that were popularized by John Doty. READ - Three "Must" Links to Read -wrt- Low Noise SWL Antenna http://groups.yahoo.com/group/Shortw...na/message/949 NOTE: John Doty's 'articles' {Writings} and his 'name' are/is available freely on the Web (WWW) and thus Millions may View and Read them. AEN - ? Have you consider 're-printing' your 'articles' {Writings} on the Web (WWW) and making them Free for All to View and Read ? AEN - Doing so, may provide you with the recognition that you so justly deserve. TBL: As to whether, the "Low Noise" Antenna 'design concepts' work well for Shortwave Listener (SWL) Antennas: They have improved my Shortwave Listening with good signal levels and much lower noise. What more can I say: "I Ain't No Elmer !" Enjoy Listening to your Radio/Receivers with your Antennas. iane ~ RHF . All are WELCOME at the Shortwave Listener (SWL) "Antenna Ashram" http://groups.yahoo.com/group/Shortw...na/message/502 Some Say: On A Clear Day You Can See Forever. I BELIEVE: On A Clear Night . . . You Can Hear Forever and Beyond, The BEYOND ! [ With the a SWL Antenna of your own making. ] . . |
In article .com,
"RHF" wrote: DALLAS {aka: AEN} , Long ago John Doty corrected me on the 'fact' that he did not "Invent" these Antennas or the Design Concepts of these Low Noise Antennas. Snip Scientists and engineers have been pondering electromagnetism, antennas and transmission lines for a century so it's hard to come up with something new. -- Telamon Ventura, California |
Some of Dallas' excellent articles are indeed on the Web. Check out
http://www.kongsfjord.no and look under the section "The Dallas Files". I particularly have benefited from his review and mods for the ICOM IC-746Pro, as it helped me in my decision to buy and modify a IC-756Pro (which as very similar receive circuitry). Guy Atkins Puyallup, WA USA "RHF" wrote in message oups.com... SNIP AEN - ? Have you consider 're-printing' your 'articles' {Writings} on the Web (WWW) and making them Free for All to View and Read ? SNIP |
Alfred E. Newman wrote:
Hi whatever your name is, I am puzzled. If, as you wrote, John corrected you on the 'fact' that he did not "Invent" these Antennas or the Design Concepts of these Low Noise Antennas, then presumably he told you who did. So why have he and you neglected to mention that in your writings? RHF can't tell you because I didn't tell him. I didn't tell him because I don't know. I know that the principles behind this kind of system were well understood by radio engineers 70 years ago. I don't know the original sources. The idea of using a transmission line to prevent EMI pickup goes back at least to 1877. According to the February 19, 1881 issue of Scientific American, the US patent office ruled (in a dispute with Alexander Graham Bell) that David Brooks had invented the "return wire" as a way to reduce crosstalk between telegraph and telphone lines (and if someone were to cite earlier work by, say, Kelvin, I wouldn't be surprised). It was Denzil Wraight, in fact, who rediscovered Strafford's work on noise reducing antennas, and who discovered by trial and error reasonable turns ratios for the antenna matching transformers (Strafford does not discuss that in his articles). So it is Strafford and Wraight that Doty plagiarized and you failed to cite. I've never heard of either of these people. My approach is apparently more theoretical: if you understand the physics you don't need to experiment with turns ratios (it's a "back of the envelope" calculation). My writing is my own, not copied from anyone. The design itself is a combination of well known ideas that should be obvious to an expert: that makes it engineering, not invention. Denzil used a vertical noise reducing antenna, wrote me about how well it worked, and included a copy of Strafford's Wireless World article. First I constructed a "top fed" vertical version with mast almost touching my house. I didn't expect it to do much fow man made noise in the MW band (my main interest), but to my surprise it did. In my case, there was little, if any, difference noise reduction between mounting the vertical mast almost touching my house, or 100 feet away. So this kind of noise reducing antenna is ideal for DXers with limited space. Next I implemented an inverted L version of Strafford's noise reducing antennas. If I recall correctly, the first L was about 100 feet horizontal and 15 feet vertical. I experimented with both base feed and top feed. Both gave excellent noise reduction in the MW (and VLF) band(s). Both Denzil and I used twin feed instead of coax because twin feed tends to pick up less local nois than coax. If you're getting less pickup with twin lead than coax, there's something amiss with the way you're using the coax. In general, coax picks up much less than twinlead. The EM field of coax is confined within the cable. The field of twinlead surrounds the cable, making it much more susceptible to to external coupling. Denzil and I wrote two separate articles for DX news (The National Radio Club http://www.nrcdxas.org/ reprint A69) that were published in the early summer of 1991. I had sent Mark Connelly preprints of our arfticles, and he developed coax feed versions of Strafford's noise reducing antennas. According to Mark, the coax feed variant picked up little, if any additional noise compared to the twin feed version. At one point in these experiments I tried shielded twin lead, but found no further noise reduction (or increase). I got to know Mark a few years after I wrote the article. His approach is similar to mine, but there are some important differences. He uses transformers for isolation as well as matching. I shunt the common mode current to ground at the ground stakes, while absorbing the common mode energy by burying the coax between them. Mark never accused me of intellectual theft. Presently I use top fed inverted L noise reducing antennas as parts of my phased arrays. Unless you are listening above 16 MHz or so, or have an insensitive receiver, you don't really need (or want) a big inverted L. Mine are 15 feet up and 30 feet horizontal. The matching transformer we used then (and which I still use now) is an Amidon FT-114-75 (the 75 material may have been replaced with J material), 43 turns to 9 turns (at the center of the 43 turns) #20 enameled copper wire. The twin lead I still use is Radio Shack speaker wire (#18 stranded, 7 strands of, I think, #26). It is cheaper ane easier to use than real twin lead, and had about the right characteristic impedance (about 100 ohms). You'll need a balun (1:1) at your receiver to convert the balanced lead in to your unbalanced receiver antenna input (9 bifilar turns of #20 enameled on an FT-114-75 will do). Like I said before, the noise reducing properties of these kinds of antennas begin to decline as you go higher in frequency, and above 6 MHz there is not much noise reduction. If you believe you got substantial noise reduction above 6 MHz due only to using one of these kinds of antennas, then you are mistaken. For SW, Strafford recommended doublet antennas for noise reduction. I do not have much experience with these because I am not much of a SW listener. What little experience I have suggests that phased arrays are much more effective at reducing SW noise sources. Unfortunately,there are no good phasers that you can buy. I measured 36 dB of EMI reduction at 25 MHz with one of my antennas. If you're not getting good EMI reduction at SW there's some important difference between your approach and mine. As for publishing these articles on the web, that would involve considerable work. The articles were produced with typewriters, and contain hand drawings. To convert them to .PDF or other files would be non-trivial, and would require NRC approval. Anyone who wants these articles can easily purchase them as reprints from the NRC at the web site above using PayPal or other methods of payment. The trouble is that most people who are interested will never even know what to order. Allowing your work to be freely published on the web is a good way to get it circulated. Credit for ideas tends to flow to those whose disseminate them, regardless of precedence or the desires of the people involved. Best regards, Dallas -jpd |
dallas, Dalas. DALLAS !
"RHF" are my 'initials' and for most of my work life I was "RHF" DALLAS - Now I say that "I am a Work-A-Holic in Recovery; Living Retired, Healthy and Free in OK-Land, Cali-4-Ni-A." - "RadioHighFreq" on Yahoo eGroups. - "Retired-Health-and-Free" on eBay. - My eMail Address for Rec.Radio.Shortwave is Anyone what to guess what my initials are ? ? ? DALLAS ? So tell me Dallas why do you post here as "Alfred E. Newman" ? DALLAS - Here is what John Doty 'posted' : - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - John Doty Jan 11, 2004 @ 7:35 pm show options Newsgroups: rec.radio.shortwave From: (John Doty) Date: 11 Jan 2004 19:35:33 -0800 Local: Sun, Jan 11 2004 7:35 pm Subject: N8KDV Random Wire Antennas -&- N8KDV Ten-to-One (10:1) Matching Transformer Reply | Reply to Author | Forward | Print | Individual Message | Show original | Report Abuse N8KDV wrote in message ... Also, I'm afraid to point out that the design pre-dates the John Doty concept. (as far as I know). True. There was nothing really new in my design. I wrote up the design because I hadn't seen a good clear explanation of nonresonant wire antennas with effective common mode decoupling. The article has been posted on several web sites and published in several newsletters: people seem to find it helpful. But it doesn't represent an invention, it's just a piece of writing. John Doty "You can't confuse me, but an unreliable news server can make posting difficult!" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - DALLAS - Here is my 'reply' - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - RHF Jan 12, 2004 @ 1:47 am show options Newsgroups: rec.radio.shortwave From: (RHF) Date: 12 Jan 2004 01:47:14 -0800 Local: Mon, Jan 12 2004 1:47 am Subject: N8KDV Random Wire Antennas -&- N8KDV Ten-to-One (10:1) Matching Transformer Reply | Reply to Author | Forward | Print | Individual Message | Show original | Report Abuse JPD, I guess I will have to to change my attribution line. FROM: Low Noise Antenna Design Concepts - written by John Doty TO: Low Noise Antenna Design Concepts - as popularized by the writings of John Doty http://www.anarc.org/naswa/badx/ante...e_antenna.html Build-It-YourSelf and Hear the Difference. From the Association of North American Radio Clubs (ANARC) WebSite and the Rec.Radio.ShortWave (NG) WebPage. IMHO: No one can deny that your Writings about the Low Noise Antenna Design Concepts have 'helped' to "Popularize" those design concepts. iane ~ RHF .. .. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - About "POPULARIZE" : Legendary "Henry Ford" may not have invented or engineered the Automobile; but no one can dispute that he was a prime figure in POPULARIZING the Automobile in the USofA by making a 'basic and reliable' Automobiles like the Model "A" and "T that were Economically Affordable for many Americans. One could make the same statement about Bill Gates and MicroSoft; MS-DOS and Windows. DALLAS - I Remain 'rhf' ~ RHF - aka - a Really Happy Fella :o) .. .. |
Alfred E. Newman wrote:
John Doty's noise reducing antenna ideas from his 1993 posting are virtually identical to noise reducimg antenna ideas found in articles by Denzil Wraight and me which were published in DX News in 1991. Decoupling a feedline is decoupling a feedline.... Denzil's article was titled "Interference Reducing Antennas For The BCB," and mine was "Inverted L Noise Reducing MF/VLF Antenna." Is that an oximoron? Seriously...Using an omnidirectional antenna to reduce *noise* on those bands is kinda counterproductive seems to me... Denzil and I used twinlead rather than coax. However, Mark Connelly published descriptions of similar noise reducinmg antennas using coax in DX News later in 1991. These articles are available from The National Radio Club http://www.nrcdxas.org/ as reprint A69. Contrary to what John claims, these kinds of noise reducing antennas are not very effective against noise at SW frequencies much above 6 MHz. Uhh...Decoupling a feedline is decoupling a feedline. No matter what frequency... You can do it at 440 mhz just fine... All my antennas are well decoupled, and that includes from MW to 440 mhz. These types of noise reducing antennas were invented by F. R. W. Strafford in or about 1936, and he discusses these and other types of noise reducing antennas for short waves in "Screened Aerials," Wireless World, November 25, 1937, pages 516 - 518. Decoupling the feedline has been around for quite a while... I guess I have one issue though, and yes, I am anal retentive...I object to *any* antenna being called a "low noise" antenna. Why? Cuz they don't exist. These is no such thing. They should describe all of these types of decoupled antenna schemes as "examples of better decoupled antenna *systems*. The lower noise has nothing to do with the antenna itself. Only the decoupling of the line, coax or ladder line. And to top this off, if you are in a quiet area with no noise to pickup, using the decoupling schemes will not do *anything* at all to reduce noise. The performance will be exactly the same. IE: out in the woods, running battery power, etc...A *true* noise reducing *antenna* would work anywhere, but again, as far as I'm concerned, they don't exist. The on;y way to really reduce noise using the antenna itself, would be to change polarity. That would reduce an opposite polarized signal about 20 db or so... As far as the decoupling losing effectiveness over a certain freq, thats a design issue with the decoupling scheme being used. Balun, chokes, etc...BTW...I include the so called "shielded loops" with the "misnamed" antenna group. In all tests I've ever run, I've never seen any indication a shielded loop is any *quieter* to noise pickup than a regular open loop. But the reason there is not due to decoupling of the feedline per say, although a lack of decoupling can effect the overall balance. It's due to the shielded loop providing inherent good balance due to it's design. But if you have an open loop just as well balanced, it will null noise sources just as well as a shielded loop. A shielded loop is not any quieter to far field noise, than any other loop if you are not using it to null the noise source. It *could* do a better job of nulling that source, *if* the balance on the open loop was poorer, but again, this is a design issue..You can design the open loop to be just as balanced. MK -- http://web.wt.net/~nm5k |
Mark Keith wrote:
I guess I have one issue though, and yes, I am anal retentive...I object to *any* antenna being called a "low noise" antenna. Why? Cuz they don't exist. These is no such thing. They should describe all of these types of decoupled antenna schemes as "examples of better decoupled antenna *systems*. One trouble is that many potential readers wouldn't understand such a pedantic article title. The lower noise has nothing to do with the antenna itself. Only the decoupling of the line, coax or ladder line. You can't decouple the line from an unbalanced antenna that lacks a counterpoise. You can argue that really isn't an antenna (and I would agree!), but such things are sold as "antennas". The most commonly recommended "antenna" for the newbie is a "random wire", technically only half of an unbalanced dipole. Even professionals aren't immune from this technical error: unbalanced dipoles are often called "monopoles" even though Maxwell's equations forbid a true monopole antenna. Even if a counterpoise is present, the design of the antenna influences your ability to effectively decouple it from the line. Ungrounded but unsymmetrical antennas (like "slopers") are particularly troublesome. And to top this off, if you are in a quiet area with no noise to pickup, using the decoupling schemes will not do *anything* at all to reduce noise. The performance will be exactly the same. IE: out in the woods, running battery power, etc...A *true* noise reducing *antenna* would work anywhere, but again, as far as I'm concerned, they don't exist. In the article in question, I wrote, "The real trick with a shortwave receiving antenna system is to keep your receiver from picking up noise from all the electrical and electronic gadgets you and your neighbors have". Plainly, I was not talking about receiving systems out in the woods. I'm a professional physicist: I can be as fussy and pedantic as you'd like. Unfortunately, that rarely leads to effective communication. SWL's write to me to tell me that following my advice has improved their reception, and several DX websites host copies of my article. I like to think that shows I've communicated something that matters to people. You seem to know quite a bit about this stuff: why not write up *your* approach to these issues? -jpd |
In article , Mark Keith wrote:
Alfred E. Newman wrote: John Doty's noise reducing antenna ideas from his 1993 posting are virtually identical to noise reducimg antenna ideas found in articles by Denzil Wraight and me which were published in DX News in 1991. Decoupling a feedline is decoupling a feedline.... Denzil's article was titled "Interference Reducing Antennas For The BCB," and mine was "Inverted L Noise Reducing MF/VLF Antenna." Is that an oximoron? Seriously...Using an omnidirectional antenna to reduce *noise* on those bands is kinda counterproductive seems to me... Denzil and I used twinlead rather than coax. However, Mark Connelly published descriptions of similar noise reducinmg antennas using coax in DX News later in 1991. These articles are available from The National Radio Club http://www.nrcdxas.org/ as reprint A69. Contrary to what John claims, these kinds of noise reducing antennas are not very effective against noise at SW frequencies much above 6 MHz. Uhh...Decoupling a feedline is decoupling a feedline. No matter what frequency... You can do it at 440 mhz just fine... All my antennas are well decoupled, and that includes from MW to 440 mhz. These types of noise reducing antennas were invented by F. R. W. Strafford in or about 1936, and he discusses these and other types of noise reducing antennas for short waves in "Screened Aerials," Wireless World, November 25, 1937, pages 516 - 518. Decoupling the feedline has been around for quite a while... I guess I have one issue though, and yes, I am anal retentive...I object to *any* antenna being called a "low noise" antenna. Why? Cuz they don't exist. These is no such thing. They should describe all of these types of decoupled antenna schemes as "examples of better decoupled antenna *systems*. The lower noise has nothing to do with the antenna itself. Only the decoupling of the line, coax or ladder line. And to top this off, if you are in a quiet area with no noise to pickup, using the decoupling schemes will not do *anything* at all to reduce noise. The performance will be exactly the same. IE: out in the woods, running battery power, etc...A *true* noise reducing *antenna* would work anywhere, but again, as far as I'm concerned, they don't exist. The on;y way to really reduce noise using the antenna itself, would be to change polarity. That would reduce an opposite polarized signal about 20 db or so... As far as the decoupling losing effectiveness over a certain freq, thats a design issue with the decoupling scheme being used. Balun, chokes, etc...BTW...I include the so called "shielded loops" with the "misnamed" antenna group. In all tests I've ever run, I've never seen any indication a shielded loop is any *quieter* to noise pickup than a regular open loop. But the reason there is not due to decoupling of the feedline per say, although a lack of decoupling can effect the overall balance. It's due to the shielded loop providing inherent good balance due to it's design. But if you have an open loop just as well balanced, it will null noise sources just as well as a shielded loop. A shielded loop is not any quieter to far field noise, than any other loop if you are not using it to null the noise source. It *could* do a better job of nulling that source, *if* the balance on the open loop was poorer, but again, this is a design issue..You can design the open loop to be just as balanced. MK "...I object to *any* antenna being called a "low noise" antenna. Why? Cuz they don't exist. These is no such thing." Low noise antennas exist and one type is a shielded loop. The noise improvement is from local noise sources not distant radiating far fields. Inefficiently radiating local noise sources tend to spread out the electric field where the magnetic field stays closer to the source. These are induction fields not radiating fields. It is well known that local noise source problems are due to common mode inductive electric field pickup. Mono-poles (Marconi 1/4 wave) and dipoles are examples of voltage sensitive antennas. Loop or folded dipoles are examples of antennas more sensitive to magnetic fields than electric. A Mono-pole is great at picking up common mode electric fields and is the worst type in noisy areas. It is very insensitive to local magnetic fields. Small unshielded loops are good at picking up local magnetic fields and poor at picking up local electric fields. Shielding the loop makes it even less sensitive to local electric fields. Decoupling the unbalanced transmission line allow a balanced antenna to stay that way. The balanced antenna is less sensitive to local common mode electric fields. Decoupling the transmission line helps prevent noise picked up on it's outer shield from coupling to the antenna or noise from the mains supply, through the radio and coax from coupling to the antenna. If you don't live in the woods and if you or your neighbors have electrically noisy electronic devices that radiate poorly but still generate spread out electric common mode fields then the worst type to best type relative to another is: 1. 1/4 wave Marconi mono-pole electric field sensitive unbalanced. 2. 1/2 wave dipole electric field field sensitive balanced antenna. 3. 1 wavelength or larger loop antenna which is a mix of electric and magnetic field sensitive antenna. This antenna is balanced. 4. 1/10 wave or less loop antenna which is balanced, mostly magnetic sensitive and has very poor electric field pickup. 5. 1/10 wave or less shielded loop which is generally better balanced than unshielded and the least sensitive to local noise electric fields. RELATIVELY SPEAKING "5" is a "low noise" antenna compared to "1" as far as locally generated noise is concerned. -- Telamon Ventura, California |
"...It was Denzil Wraight, in fact, who rediscovered Strafford's work
on noise reducing antennas,..." After reading the above statement I don't see where you and Denzil have created something that could be plagarized. You and Denzil did what a lot of others have done in the world of amateur radio, and that is to use, combine and possibly update the work of others. It is great that you have continued the research on noise reducing antennas, but by your own words you cannot claim ownership. This topic has been researched and rehashed for decades. Since Strafford published in 1937 and is probably long gone from this world, his descendants should be the ones to raise a complaint. But then again maybe Strafford used the work of someone else...what do you think. |
I'm not complaining, or have any problems with your article. I also
didn't read it before writing the post, although I think I have read it some time in the past. The reason I bring it up, is some seem to get the idea that the antennas themselves are "quieter". As far as local noise, and decoupling, I don't consider adding decoupling to an antenna, as making it "low noise", even though that may be an end result. I just consider that as allowing the antenna to work properly, without the feedline becoming part of the antenna. All my antennas are decoupled, and I consider *none* of them as being "low noise" antennas. I have no interest in writing articles per say. I "write" up my approaches to this, right here on usenet. As far as "incomplete" antennas, I don't spend much time thinking about them, as I don't use them. I mean, if you look at the title, "Noise reducing antennas", it's very misleading to some. Or could be. There is no such thing. |
Low noise antennas exist and one type is a shielded loop. The noise
improvement is from local noise sources not distant radiating far fields. Of course. To me, this proves my point about the antenna in itself. But again, I don't consider adding decoupling as making an antenna or even antenna system "low noise". That might be an end result to a guy with loads of local noise, but to a guy in the woods, it means nada...His noise level in the woods should still be the same. As far as #1, 1/4 wave Marconi mono-pole electric field sensitive unbalanced., as being a worst case, I would think that depends on how it's set up. IE: grounded at the base, radials, etc as John mentioned...I never run "incomplete" antennas. Ever... My 1/4 wave's are not overly prone to common mode problems, but as I mentioned, if I use a 1/4 wave, it would be properly installed with the lower "half" of the antenna included, either as radials, or at least grounded. A balanced coax fed dipole can be quite bad, if the operation of the choke, balun, etc is not functioning properly. This would usually show up more on bands higher than it's half wave length. IE: Using a 40 meter dipole on 20 meters, etc..With the hi Z feed on 20m, a usual 1:1 balun would be fairly useless as far as decoupling the feedline. MK BTW, if the type on these post's gets goofy, it's cuz I'm using the new google "beta" and the line wrapping has changed, and is driving me nuts...It wants to run off the page forever, unless I manual hit return, and that drives me crazy. The "old" google, auto wrapped as you typed. Why do they always have to mess up something that works perfectly well as is....Or was...Overall, I don't like this new google beta much at all. |
Low noise antennas exist and one type is a shielded loop. The noise
improvement is from local noise sources not distant radiating far fields. Of course. To me, this proves my point about the antenna in itself. But again, I don't consider adding decoupling as making an antenna or even antenna system "low noise". That might be an end result to a guy with loads of local noise, but to a guy in the woods, it means nada...His noise level in the woods should still be the same. As far as #1, 1/4 wave Marconi mono-pole electric field sensitive unbalanced., as being a worst case, I would think that depends on how it's set up. IE: grounded at the base, radials, etc as John mentioned...I never run "incomplete" antennas. Ever... My 1/4 wave's are not overly prone to common mode problems, but as I mentioned, if I use a 1/4 wave, it would be properly installed with the lower "half" of the antenna included, either as radials, or at least grounded. A balanced coax fed dipole can be quite bad, if the operation of the choke, balun, etc is not functioning properly. This would usually show up more on bands higher than it's half wave length. IE: Using a 40 meter dipole on 20 meters, etc..With the hi Z feed on 20m, a usual 1:1 balun would be fairly useless as far as decoupling the feedline. MK BTW, if the type on these post's gets goofy, it's cuz I'm using the new google "beta" and the line wrapping has changed, and is driving me nuts...It wants to run off the page forever, unless I manual hit return, and that drives me crazy. The "old" google, auto wrapped as you typed. Why do they always have to mess up something that works perfectly well as is....Or was...Overall, I don't like this new google beta much at all. |
"N",
Its about 'effective communication' as John Doty posted earlier in this thread. The average Shortwave Listener (SWL) who owns a Shortwave Radio and WANTS More-Out-of-It; simply wants to 'know': - What to Buy and How to Put It Up. - Or - What to Build and How to Do It. - NO Rhyme-or-Reason is Required [.] [ Please - Just Tell Me - What To Do ] 1. So 'suggesting' they Buy a PAR End Fed Shortwave Listener (EF-SWL) Antenna and 'configuring' the Antenna in the [Shape] of an Inverted "L" Antenna. PAR Electronics "End Fed Shortwave Listener" (EF-SWL) Antenna POPCOM= http://www.popular-communications.co...landOct04.html MT= http://www.monitoringtimes.com/html/mt2003reviews.html eHAM= http://www.eham.net/reviews/detail/3707 PAR= http://www.parelectronics.com/swl_end.htm UR= http://www.universal-radio.com/catalog/sw_ant/2205.html GE= http://www.grove-ent.com/ANT8.html Telling the SWL 'what-to-do' in general simple terms. http://tinyurl.com/66lhs http://tinyurl.com/683gd http://tinyurl.com/4qmqw 2. Or simply 'recommending' that they READ three WebPages to gain some understanding of the "Low Noise" SWL Antenna. http://tinyurl.com/4kp7m CONSIDER BUILDING A "LOW NOISE" ANTENNA: Try building an Improved SWL Random Wire Antenna that uses a 9:1 Matching Transformer (Balun / MLB) then you may not see any real 'improvement' in your receive signal. This is the so called "Low Noise" SWL Antenna. Three "Must" Links to Read -wrt- Low Noise SWL Antenna http://groups.yahoo.com/group/Shortw...na/message/949 [ Please READ These Three Links ] http://www.anarc.org/naswa/badx/ante...e_antenna.html http://www.anarc.org/naswa/badx/ante..._longwire.html http://www.anarc.org/naswa/badx/antennas/grounding.html ABOUT THE "LOW NOISE" ANTENNA 'DESIGN CONCEPTS': A Random Wire Antenna Element coupled via a 9:1 Matching Transformer at the Near-End of the Antenna with a Ground Rod and Coax Cable Feed-in-Line to the Receiver. This is the basic SWL Antenna that uses the "Low Noise Antenna" 'design concepts' that were {popularized} by John Doty. .. .. All are WELCOME at the Shortwave Listener (SWL) "Antenna Ashram" http://groups.yahoo.com/group/Shortw...na/message/502 Some Say: On A Clear Day You Can See Forever. I BELIEVE: On A Clear Night . . . You Can Hear Forever and Beyond, The BEYOND ! [ With the a SWL Antenna of your own making. ] .. .. |
RHF wrote: "N", Its about 'effective communication' as John Doty posted earlier in this thread. I think I've fairly well communicated my thoughts on the matter... Thats all I intended to do. But it seems some have problems with even that.. Every time I post something here, I get a load of @$#^$*%('s climbing down my back. Get over it! If you disagree with something I say, fine. I have no problems with that. But to harp just because I won't dumb myself down to your "supposed" r.r.s.w. monkey level status, really starts to grate on my nerves. The average Shortwave Listener (SWL) who owns a Shortwave Radio and WANTS More-Out-of-It; simply wants to 'know': I'm not an "average" shortwave listener, and I don't claim to cater to them. Actually, I don't claim to cater to anyone....It's not my job. - What to Buy and How to Put It Up. That will stir more conflict than this thread....:/ - Or - What to Build and How to Do It. I think the user should decide that. Not some guy 1000 or more miles away... Only he knows what he really wants or needs..I have no problems telling someone how to build something, but for the most part, it's all been covered a zillion times over...Thats why they sell books. Thats why I have books. - NO Rhyme-or-Reason is Required [.] I can't live that way myself. I refuse to be "dumbed down" to trained monkey level, just because this is a shortwave listeners group. If I get too technical for some, "which I really don't think I do", or I get anal retentive because people keep calling certain antennas "low noise", they can just ignore it. Many people *do* want to know the truth,or maybe a little more detail about certain things. They may not reply to any of the posts. Many people read the stuff,that never actually post. It's not like I use a bunch of fancy named mumbo jumbo, or obtuse theories designed to confuse people. If they want to call them "lower noise antenna systems", I'd have less problem with that. But as I said, I don't consider simply decoupling a feedline as making it a "low noise" antenna system. Even if that could be the end result for some. It's just acting normally without the common currents screwing up the operation. If you take a milked down stock 302 ford engine with say 150 hp when running normally, and 2 plugs are fouled, allowing only 110 hp out, changing all the plugs does not make the engine a blueprinted 400 hp race engine. It will now run properly with the new plugs, but it will still be the same stock 150 hp engine. This probably won't make much sense to you, but that's a fairly fitting analogy I think... The decoupled antenna system is just acting normally. The un-decoupled antenna system is not. It's a defective system. It would be more accurate to call such a system a "high noise" system, than it is to call the decoupled system "low noise". Or to me anyway... I just want to make sure people understand that the lower noise they experience is due to decoupling the feedline from the antenna, and has nothing to do with the antenna itself. I'm sure many already realize this. But it seems fairly obvious many don't. I'm also sure not *everyone* wants to live in the dark like a mushroom. I make no apologies for being anal retentive. That is my job. :) [ Please - Just Tell Me - What To Do ] Why? It's not my job....:/ You should already be fairly well set up anyway judging from all the links you post ...:) MK |
MK,
All of what you have written defines You 'being' YOU ! {and that is Good} All of what I have written defines Me 'being' ME ! {and that is Good} .. i guess we are communicating - pal ~ RHF .. .. |
Guys Guys - there is both room for, and value in, both approaches.
I'm glad that both of you post here. Keep those antenna tips coming! Bruce Jensen |
"bpnjensen" wrote in message oups.com... Guys Guys - there is both room for, and value in, both approaches. I'm glad that both of you post here. Keep those antenna tips coming! Which reminds me.... I was perusing the ground articles in hard-core-dx.com, and I was curious about one of the articles there (probably was one of John's) stating that a good way of eliminating common mode interference is to ground the shield separately away from the 9:1 transformer. That I can do easily, but I was curious about the next statement about attaching the ground directly to the shield. My thinking is that it would be smarter to attach the ground to the shield via a ground block, but the only ground blocks I can find use the F connectors, not the 239/259 ones. Is it necessarily a good idea to strip the coating off the coax, exposing the shield, and clamping that shield to the ground rod? Seems like you'd be exposing the connection to the elements, probably hastening the demise of the coax at that point. Not to mention the changing of the interaction of the two conductors by changing it's form... --Mike L. |
"Michael Lawson" wrote in message ... "bpnjensen" wrote in message oups.com... Guys Guys - there is both room for, and value in, both approaches. I'm glad that both of you post here. Keep those antenna tips coming! Which reminds me.... I was perusing the ground articles in hard-core-dx.com, and I was curious about one of the articles there (probably was one of John's) stating that a good way of eliminating common mode interference is to ground the shield separately away from the 9:1 transformer. That I can do easily, but I was curious about the next statement about attaching the ground directly to the shield. My thinking is that it would be smarter to attach the ground to the shield via a ground block, but the only ground blocks I can find use the F connectors, not the 239/259 ones. Is it necessarily a good idea to strip the coating off the coax, exposing the shield, and clamping that shield to the ground rod? Seems like you'd be exposing the connection to the elements, probably hastening the demise of the coax at that point. Not to mention the changing of the interaction of the two conductors by changing it's form... --Mike L. |
"Michael Lawson" wrote Which reminds me.... I was perusing the ground articles in hard-core-dx.com, and I was curious about one of the articles there (probably was one of John's) stating that a good way of eliminating common mode interference is to ground the shield separately away from the 9:1 transformer. That I can do easily, but I was curious about the next statement about attaching the ground directly to the shield. My thinking is that it would be smarter to attach the ground to the shield via a ground block, but the only ground blocks I can find use the F connectors, not the 239/259 ones. Is it necessarily a good idea to strip the coating off the coax, exposing the shield, and clamping that shield to the ground rod? Seems like you'd be exposing the connection to the elements, probably hastening the demise of the coax at that point. Not to mention the changing of the interaction of the two conductors by changing it's form... --Mike L. http://www.harger.com/catalog2004/4_3_1.pdf has examples of typical Andrews Wire Co produced shield grounding kits. It is advisable to cover with waterproofing materials any connection that is exposed to the weather. There is also no such " changing of the interaction of the two conductors by changing it's form..." Btw, my "noise limiting antenna" comes from an old design published in Fine Tuning's Proceedings, in which one side of a dipole-type Balun is grounded at the feedpoint (also on the ground) and the longwire antenna is connected to the Balun's other antenna connection. Coax feedline comes out the bottom of the Balun, and is shield grounded twice for lightning protection: once at the Balun and another time before it enters the station. Besides an excellent and very quiet listening antenna, this is also a transmitter. It has worked over 500 miles on 2 Mhz and 3,000 miles on 8 Mhz. Jack Painter Virginia Beach Virginia |
"Jack Painter" wrote in message news:J%sud.3067$7p.1654@lakeread02... "Michael Lawson" wrote Which reminds me.... I was perusing the ground articles in hard-core-dx.com, and I was curious about one of the articles there (probably was one of John's) stating that a good way of eliminating common mode interference is to ground the shield separately away from the 9:1 transformer. That I can do easily, but I was curious about the next statement about attaching the ground directly to the shield. My thinking is that it would be smarter to attach the ground to the shield via a ground block, but the only ground blocks I can find use the F connectors, not the 239/259 ones. Is it necessarily a good idea to strip the coating off the coax, exposing the shield, and clamping that shield to the ground rod? Seems like you'd be exposing the connection to the elements, probably hastening the demise of the coax at that point. Not to mention the changing of the interaction of the two conductors by changing it's form... --Mike L. http://www.harger.com/catalog2004/4_3_1.pdf has examples of typical Andrews Wire Co produced shield grounding kits. It is advisable to cover with waterproofing materials any connection that is exposed to the weather. There is also no such " changing of the interaction of the two conductors by changing it's form..." I dredged up my old Halliday and Resnick text, and took a look. Yes, you are correct. The important part is the shield surrounding the core. Btw, my "noise limiting antenna" comes from an old design published in Fine Tuning's Proceedings, in which one side of a dipole-type Balun is grounded at the feedpoint (also on the ground) and the longwire antenna is connected to the Balun's other antenna connection. Coax feedline comes out the bottom of the Balun, and is shield grounded twice for lightning protection: once at the Balun and another time before it enters the station. Besides an excellent and very quiet listening antenna, this is also a transmitter. It has worked over 500 miles on 2 Mhz and 3,000 miles on 8 Mhz. Thanks for the info. --Mike L. |
"Michael Lawson" wrote "Jack Painter" wrote in message news:J%sud.3067$7p.1654@lakeread02... "Michael Lawson" wrote Which reminds me.... I was perusing the ground articles in hard-core-dx.com, and I was curious about one of the articles there (probably was one of John's) stating that a good way of eliminating common mode interference is to ground the shield separately away from the 9:1 transformer. That I can do easily, but I was curious about the next statement about attaching the ground directly to the shield. My thinking is that it would be smarter to attach the ground to the shield via a ground block, but the only ground blocks I can find use the F connectors, not the 239/259 ones. Is it necessarily a good idea to strip the coating off the coax, exposing the shield, and clamping that shield to the ground rod? Seems like you'd be exposing the connection to the elements, probably hastening the demise of the coax at that point. Not to mention the changing of the interaction of the two conductors by changing it's form... --Mike L. http://www.harger.com/catalog2004/4_3_1.pdf has examples of typical Andrews Wire Co produced shield grounding kits. It is advisable to cover with waterproofing materials any connection that is exposed to the weather. There is also no such " changing of the interaction of the two conductors by changing it's form..." I dredged up my old Halliday and Resnick text, and took a look. Yes, you are correct. The important part is the shield surrounding the core. Btw, my "noise limiting antenna" comes from an old design published in Fine Tuning's Proceedings, in which one side of a dipole-type Balun is grounded at the feedpoint (also on the ground) and the longwire antenna is connected to the Balun's other antenna connection. Coax feedline comes out the bottom of the Balun, and is shield grounded twice for lightning protection: once at the Balun and another time before it enters the station. Besides an excellent and very quiet listening antenna, this is also a transmitter. It has worked over 500 miles on 2 Mhz and 3,000 miles on 8 Mhz. Thanks for the info. --Mike L. No problem Mike. Btw, the grounding blocks work fine too, I use them under the house. But out in the field, and on towers particularly, the coax shield ground kits can be easier to handle. Nothing stopping you from making your own kit either, I just like Andrews products, already cut for your size cable, etc. Cheers, Jack |
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