RSGB RadCom December 2007 Issue
Those that can get access to a copy should look at the Radio Society of
Great Britain, RadCom Magazine, December 2007 issue, Technical Topics column by Pat Hawker G3VA. The topic? 50 Years of amateur antennas. He covers a lot of the perennial topics of debate in this newsgroup and provides some excellent commentary on element lengths, feedline lengths, SWR, ATU's, modes of operation and some of the controversy. Okay, it has probably all been covered elsewhere in books, on websites and in this newsgroup, but there is a lot of useful information condensed into a couple of pages. Almost a substitute fro Kraus and Terman! :-) Mike G0ULI |
RSGB RadCom December 2007 Issue
Mike Kaliski wrote:
Those that can get access to a copy should look at the Radio Society of Great Britain, RadCom Magazine, December 2007 issue, Technical Topics column by Pat Hawker G3VA. The topic? 50 Years of amateur antennas. He covers a lot of the perennial topics of debate in this newsgroup and provides some excellent commentary on element lengths, feedline lengths, SWR, ATU's, modes of operation and some of the controversy. Okay, it has probably all been covered elsewhere in books, on websites and in this newsgroup, but there is a lot of useful information condensed into a couple of pages. Almost a substitute fro Kraus and Terman! :-) Mike G0ULI Does he cover the radiation of antennas from 377 ohm "sweet spots", and the concept of using antennas to match free space's impedance? Roy Lewallen, W7EL |
RSGB RadCom December 2007 Issue
Pat Hawker was the only part that I read but lately he seems to be
rambling. The antenna reporter isn't really putting out anything of interest for the regular ham either tho I was pleased with the experimenting for QRP I terminated my subscription to Radcom this year because there rarely was anything else that was interesting. Wrote them a letter earlier this year but they didn't even acknoweledge it. Have been to the HQ by the way at St Albans or was it Hatfield? Art Mike Kaliski wrote: Those that can get access to a copy should look at the Radio Society of Great Britain, RadCom Magazine, December 2007 issue, Technical Topics column by Pat Hawker G3VA. The topic? 50 Years of amateur antennas. He covers a lot of the perennial topics of debate in this newsgroup and provides some excellent commentary on element lengths, feedline lengths, SWR, ATU's, modes of operation and some of the controversy. Okay, it has probably all been covered elsewhere in books, on websites and in this newsgroup, but there is a lot of useful information condensed into a couple of pages. Almost a substitute fro Kraus and Terman! :-) Mike G0ULI |
RSGB RadCom December 2007 Issue
art ) writes:
Pat Hawker was the only part that I read but lately he seems to be rambling. I'm rather surprised that he's still doing the column. It's been thirty years since I bought a collection of Technical Topics, and later I found a used one dating from the sixties. I have no idea when he started doing it (wait, I guess if this is "50 years of antenna topics" then it must be fifty years), but I suspect nobody has had such a long running column in the ham magazines. Of course, such columns are relatively easy to write, since it's a filtering of a lot of material down to it's essence. Michael VE2BVW |
RSGB RadCom December 2007 Issue
"Roy Lewallen" wrote in message ... Mike Kaliski wrote: Those that can get access to a copy should look at the Radio Society of Great Britain, RadCom Magazine, December 2007 issue, Technical Topics column by Pat Hawker G3VA. The topic? 50 Years of amateur antennas. He covers a lot of the perennial topics of debate in this newsgroup and provides some excellent commentary on element lengths, feedline lengths, SWR, ATU's, modes of operation and some of the controversy. Okay, it has probably all been covered elsewhere in books, on websites and in this newsgroup, but there is a lot of useful information condensed into a couple of pages. Almost a substitute fro Kraus and Terman! :-) Mike G0ULI Does he cover the radiation of antennas from 377 ohm "sweet spots", and the concept of using antennas to match free space's impedance? Roy Lewallen, W7EL Hi Roy, He does mention that antennas possess radiation resistance, not to be confused with and not the same as, characteristic impedence (or feedpoint impedence) and that the characteristic impedence will vary along an antennas length. As for the actual point(s) along an element at which an antenna radiates (transfers energy to free space) with maximum efficiency, he makes no comment. I seriously doubt that there is anything in the article that you would dispute. It seems that everyone was so busy laughing on this newsgroup, that no one has actually provided any information as to whether any detailed research has ever been carried out as to what is going on within the radiating elements of an antenna. There is loads of theory in the text books, but I have yet to see any empirical measurements or results. I am aware of the research into small loops carried out by Professor Underhill (also published in RadCom) but it seems that even his results have been disputed. I may have submitted the post, tongue in cheek, to stir things up a bit, but on reflection there seems to be something of merit in the idea. I am revisiting the appropriate chapters in Kraus and Terman to see where the error in my logic is. In the absence of any direct evidence of contradiction, I think it may be worth developing this idea and making a few measurements of my own to see what the truth of the matter is. Amateur radio is supposed to be a learning experience, right? And you can't learn without making mistakes. After 40 years of following the diktats of professional communications and electronic theory, I think the time is right to kick off the traces and challenge some of the accepted authodoxies. I do know all the conventional stuff, it just doesn't satisfy my soul. You probably know more about antennas than anyone has a right to know Roy, but it's a strange universe out there and it's just possible that there's a few more things to learn yet. Regards Mike G0ULI |
RSGB RadCom December 2007 Issue
"art" wrote in message ... Pat Hawker was the only part that I read but lately he seems to be rambling. The antenna reporter isn't really putting out anything of interest for the regular ham either tho I was pleased with the experimenting for QRP I terminated my subscription to Radcom this year because there rarely was anything else that was interesting. Wrote them a letter earlier this year but they didn't even acknoweledge it. Have been to the HQ by the way at St Albans or was it Hatfield? Art Mike Kaliski wrote: Those that can get access to a copy should look at the Radio Society of Great Britain, RadCom Magazine, December 2007 issue, Technical Topics column by Pat Hawker G3VA. The topic? 50 Years of amateur antennas. He covers a lot of the perennial topics of debate in this newsgroup and provides some excellent commentary on element lengths, feedline lengths, SWR, ATU's, modes of operation and some of the controversy. Okay, it has probably all been covered elsewhere in books, on websites and in this newsgroup, but there is a lot of useful information condensed into a couple of pages. Almost a substitute for Kraus and Terman! :-) Mike G0ULI Hi Art, That is true, but he has been a columnist for years and years, and there must come a time when you start to go round in circles. Rather too much emphasis on low noise mixers and old valve circuits for my taste but sometimes there is a real gem, like this month. The homebrew column that has been appearing for the last few months has been very good and very practical. The head office is in Potters Bar, just off the M25 motorway. They have quite a nice station that licensed visitors can operate, with prior notice. The staff are always friendly but are rather busy all the time so are not really in a position to stand around having long chats. Cheers Mike G0ULI |
RSGB RadCom December 2007 Issue
On Thu, 15 Nov 2007 02:47:05 -0000, "Mike Kaliski"
wrote: It seems that everyone was so busy laughing on this newsgroup, Hi Mike, As well crafted a line for trolling as any.... that no one has actually provided any information as to whether any detailed research has ever been carried out as to what is going on within the radiating elements of an antenna. This, as the lawyers would say, argues a fact not yet in evidence. Your statement appears to be one that can only be satisfied by meeting a string of conditions: 1. The actuality of "actually," who is the arbiter of this? This group has long experienced denial by inventors that their theories have never been "actually" disproved. "Actually" is one of those rubbery words that fits any argument that lack definition; 2. "detailed research?" Another qualifier that invites the rejection of any contribution for lacking unspecified requirements; 3. "what is going on?" Now THERE is a technical goal for detailed research to be provided as information. 4. "within the radiating elements?" Is this to presume there is some distinct radiation from "within" elements? This would be a remarkable measurement achievement to tease it out from the rest. [Could we use a Gaussian sieve?] There is loads of theory in the text books, but I If you moved to the fiction shelves would you say there is loads of drama in them? [More to the matter, what would you expect?] have yet to see any empirical measurements or results. Of what? Actual detailed results of what is going on within radiating elements? Help us out here. What instrumentation would be used? What units of measure would be employed? (In "what is going on" are we talking about Ohms, Volts, Amperes; or swimming, having a party, or getting laid off?). What qualifies as detail? How would we recognize it being actual? I am aware of the research into small loops carried out by Professor Underhill (also published in RadCom) but it seems that even his results have been disputed. Hmm, tantalizing, but how do small loops relate to "what is actually going on?" More so, where within the loop did Professor Underhill make his measurements, and what were they of? [I might point out here, editorially, that little content was posted by you up until this point, and it has evaporated following its solitary mention. If you stripped out everything, and simply fleshed out this sentence into a paragraph, it might be meaningful.] I may have submitted the post, tongue in cheek Then the joviality that your post heralds is merited, isn't it? This is called leading with your chin. , to stir things up a bit, but on reflection there seems to be something of merit in the idea. As your post seems to be wholly unrelated to the topic, and apparently a stream of consciousness from another thread, then this idea is adorned with rather vague suggestions. 73's Richard Clark, KB7QHC |
RSGB RadCom December 2007 Issue
Richard Clark wrote:
... 73's Richard Clark, KB7QHC Ahhh, at it again. A careful argument based on semantics, the authors choice of words, and standing on the arguments that no mistakes exist in our present knowledge and that new discoveries in the deep workings of antennas are yet to be discovered ... Yanno Richard, you argument is really the same argument--over, and over, and over again ... I keep wondering if others ever notice, or they all, to the VERY LAST ONE, are too polite to point out how childish it all really is? Regards, JS |
RSGB RadCom December 2007 Issue
Mike Kaliski wrote:
and that the characteristic impedence will vary along an antennas length. Well, that's obviously false. The characteristic impedance of a horizontal wire above ground is constant at 138*log(4D/d) The characteristic impedance is not to be confused with the voltage to current ratio existing on a standing-wave antenna any more than the characteristic impedance of a transmission line is to be confused with the voltage to current radio existing along its length when the SWR is not 1:1. -- 73, Cecil http://www.w5dxp.com |
RSGB RadCom December 2007 Issue
Cecil Moore wrote:
Mike Kaliski wrote: and that the characteristic impedence will vary along an antennas length. Well, that's obviously false. The characteristic impedance of a horizontal wire above ground is constant at 138*log(4D/d) The characteristic impedance is not to be confused with the voltage to current ratio existing on a standing-wave antenna any more than the characteristic impedance of a transmission line is to be confused with the voltage to current radio existing along its length when the SWR is not 1:1. Have you verified this experimentally, Cecil? If you did, how did you do it? 73, Tom Donaly, KA6RUH |
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