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Doc try and think for yourself, if you know what a parallel circuit is try
and discover if it will radiate and have a reasonable input impedance. I will help you if you need it, we are only using passive elements, they are resistance, inductance and capacitance which can be in distributed, lumped for or both just as we would for a dipole type radiator. Art "'Doc" wrote in message ... Steve Troll?? Yes, troll. 'Doc |
try and think for yourself,
I am thinking: Fugetaboutit |
Hi Rich I will try to use my words carefully as I am optomistic
that we are getting close to my long term bogey. "Richard Clark" wrote in message ... On Thu, 04 Mar 2004 22:31:40 GMT, "aunwin" wrote: ... give the pros and cons between a series circuit and a parallel circuit from which to base a radiator ? ... Just to give you a start a series circuit radiator is a dipole. And we will say a parallel circuit radiator is one with at least one capacitive lumped circuit and one inductive lumped circuit in parallel. ... Here is a start A dipole provides a lot of signals at the same time( good) A parallel circuit can only supply one signal at a time (bad ) Get the idea? Hi Art, A dipole is the most efficient antenna. Well I know that is your position but what are you comparing it with and what parameters are you focussing on to form an efficiency term ? The parallel circuit offers loss to an already most efficient antenna.. Well looking at them separately rather than adding one to another. What losses are you refering to in a parallel circuit assuming that the circuit is resonant?. Is it of magnitude that one gets when adding an impedance matching unit say on a 160 metre style shortened dipole or similar antenna? A dipole is simple to load and often requires no matching. Yes, that is true and very important, possibly a good reason to make it a standard in all its different aspects with respect to ground and radiation foot print. The parallel circuit is difficult to load and always requires matching. No........ The parallel circuit need not require any external matching system which is a huge plus. A dipole offers a standard of gain. Anything can be adopted as a standard to compare to so this is a non runner. The parallel circuit offers no change in gain except the prospect of reducing it through making the antenna smaller to become a resonant system. As a dipole moves away from its resonant point gain losses occur, swr increases and limits the frequency span of use. A parallel circuit which provides movement of the resonant point has no loss in gain, minimul change in SWR and thus less constraint on frequency span that can be used. Shortening comment I fully agree with, that eventually can open many doors. A dipole is a simple construction. I fully agree The parallel circuit adds complexity which raises the prospects of mechanical and electrical failure. Yes, you are of my generation that was brought up on the idea of less moving parts. But our generation has made such huge advances in Quality control together with the introduction of solid state construction that we now have a throw away economy. In ham radio we now see solid state construction with high intricasy of moving parts, in radios, remote matching systems and yes even with antennas such as the IR antenna. Our generation is now in the minority on that subject. A dipole offers hazardous potentials at its tips. True but it has not been of sufficient danger for manufacturers to place a warning tag at each end. A parallel circuit double that danger by offering hazardous potentials at both its tips and its drive point. Should be zero change in drive point at the antenna input port and should provide less voltage hazards as it would tend to lower voltages and increase current which is the prime requirement for radiation. This point is one of the main points I fail to understand why the group will not embrace. A dipole requires isolation/insulation at its tips due to high potentials. Repeat A parallel circuit requires isolation/insulation at its drive point AND its tips due to high potentials. Is that the idea? I presume you can distinguish good/bad. 73's Richard Clark, KB7QHC Yes Richard I think that narrows the issue down very nicely and prevents mischevious comments that foster disarray. Obviously enclosed in the above there is something that I am tripping over thru the years and I have no doubt that you will eventually point to it and here I must put up or shut up. Even if it is demonstrated where I am in error it is a positive for me in a learning cycle. Could we now focus on those points that we disagree and push the others aside and only return to them if it is pointed out that we were both wrong. You continue with the lead as it is working nicely. Thanks so much for aproaching with an open mind in a true academic fashion which will eventually arrive at the main point of contention that I have failed to grasp before intential spoilers arrive as they have done with forums such as.......well you know what I mean Best regards Art |
Thats O.K. Yuri I learned from your long thread regarding
current flow in inductors which never got resolved and is waiting on your experiment. This time things appear to be different, I am asking for assistance not telling people that they are wrong. There is a difference in opinion and I am in the listening mode which is proving very productive since there as yet has been no diversive mischevious postings that moved things off focus as it did with your brouha. This is focussed on antennas which is what this newsgroup is interested in and it is staying on focus as people who are not sure of their facts are staying off. I could not ask for anything better, it is a teaching mode and not an enforcement mode so everybody learns and everybody benefits.. Regards Art "Yuri Blanarovich" wrote in message ... try and think for yourself, I am thinking: Fugetaboutit |
On Fri, 05 Mar 2004 18:34:05 GMT, "aunwin"
wrote: A dipole is the most efficient antenna. Well I know that is your position but what are you comparing it with and what parameters are you focussing on to form an efficiency term ? They are the common factors of efficiency Power Radiated / (Power Radiated - Power lost to heat) If the radiated power doesn't go where you want, that is inconvenient not inefficient. The parallel circuit offers loss to an already most efficient antenna.. Well looking at them separately rather than adding one to another. What losses are you refering to in a parallel circuit assuming that the circuit is resonant?. Is it of magnitude that one gets when adding an impedance matching unit say on a 160 metre style shortened dipole or similar antenna? Impedance does not lose power, resistance does. Additional components add resistance where there was no resistance before. The parallel circuit is difficult to load and always requires matching. No........ The parallel circuit need not require any external matching system which is a huge plus. The parallel circuit ALWAYS requires matching BY DEFINITION. There is no alternative. ALL halfwave verticals and ALL fullwave dipoles demand matching. There are no commercial sources (transmitters) or lines that drive this kind of load directly, matching is the ONLY choice. A dipole offers a standard of gain. Anything can be adopted as a standard to compare to so this is a non runner. This attitude is self-serving. The dipole is the de-facto standard barring the isotropic specification. Choose one or the other, there is no honest third choice. The parallel circuit offers no change in gain except the prospect of reducing it through making the antenna smaller to become a resonant system. As a dipole moves away from its resonant point gain losses occur, I have shown this to be false. A parallel circuit double that danger by offering hazardous potentials at both its tips and its drive point. Should be zero change in drive point at the antenna input port and should provide less voltage hazards as it would tend to lower voltages and increase current which is the prime requirement for radiation. This point is one of the main points I fail to understand why the group will not embrace. Because it is not true. A parallel resonant circuit BY DEFINITION has a high Z characteristic. A constant power (which is to say the same power you would put into a low Z characteristic, series resonant antenna) drives the voltage to hazardous levels. There is no other outcome. 73's Richard Clark, KB7QHC |
On Fri, 05 Mar 2004 01:24:04 GMT, "aunwin"
wrote: That is the longstanding convention. Same thing applies to a one wavelength dipole. All such are the basis of the J-Pole and the Zepp (when you strip away their matching sections). Well that is new to me, I never consider the matching circuit as part of an antenna but only a required band aid. Can you point me to where this is discussed ? ( J pole I know nothing about but the others I would like to read of what you refer to as a parallel circuit) This could be the point of confusion. The archives are rich in this discussion. The following quote from me covers it adequately: Matching sections to the J-Pole and the Zepp are contributors to radiation due to the unbalanced nature of those antennas designs. How much they contribute is perhaps arguable, but when they are built in without care, their contribution cannot be denied. The matching circuits contain both circulating currents and common mode currents. The common mode currents, as a function of the physical length compared to wavelength, offer radiation. The radiation may aid, or it may hinder, but it is there none the less. Not sure if you are saying 'yes'. I personaly think it is a parallel circuit to which I would answer 'yes'. No, they are NOT parallel - they could be, but there is nothing inherently parallel and it all depends on the drive and load applied. Well on that note I see a dipole as a single series circuit fed by a generator( ARRL book), where-as I see a bandpass circuit as a parallel circuit. This is a product of your shortfall of experience and instruction. I can construct a bandpass circuit using only resistors and capacitors. There is NOTHING resonant there. I can build a notch filter (the opposite of a bandpass filter) with a parallel circuit and EVERYTHING is resonant there. I can build a bandpass filter with a series resonant circuit. It is all a matter of connections, the topology as has been pointed out. Read the ARRL book on antennas and they dwell on series circuits as in dipole, why the big difference with this newsgroup? I have observed absolutely no discussion that would deny a series resonant analysis of a half wave dipole. Your comments seem to rotate about phase changes more than it does about coupling as to the main focal point. I have commented in no way, shape, or form about phase. It is wholly inappropriate to the topic. No comments on your other posting yet .(pro and con) which suggest the experts are unified on your statements. As if I cared.... Engineering is not a democracy. I will have to choose my words very, very carefully tomorrow on that one.Up to now I feel fully exposed on what I don't know that which every body else knows Them? Hardly. Few dwell on these matters as there is a script in the amateur rags that offer equivalent circuits presented at the drive point for various length radiators. The point at which you may go seriously off the track is to interpret those equivalent circuits into physical structures of an over-strained imagination. It is fine and well to simply observe that the full wave dipole has an equivalent with a parallel resonant circuit. It is vastly different to assign the physical elements of the structure of the antenna to roles of capacitor, inductor and so on to make that parallel circuit "real." 73's Richard Clark, KB7QHC |
Yup, Richard you got me fair and square. I really thought
that this discussion was going to be fruitful and pushed aside all past history. Just shows how dumb I am..But then I am sure I will not be the last one to be taken in. You really executed the situation well Art "Richard Clark" wrote in message ... On Fri, 05 Mar 2004 18:34:05 GMT, "aunwin" wrote: A dipole is the most efficient antenna. Well I know that is your position but what are you comparing it with and what parameters are you focussing on to form an efficiency term ? They are the common factors of efficiency Power Radiated / (Power Radiated - Power lost to heat) If the radiated power doesn't go where you want, that is inconvenient not inefficient. The parallel circuit offers loss to an already most efficient antenna.. Well looking at them separately rather than adding one to another. What losses are you refering to in a parallel circuit assuming that the circuit is resonant?. Is it of magnitude that one gets when adding an impedance matching unit say on a 160 metre style shortened dipole or similar antenna? Impedance does not lose power, resistance does. Additional components add resistance where there was no resistance before. The parallel circuit is difficult to load and always requires matching. No........ The parallel circuit need not require any external matching system which is a huge plus. The parallel circuit ALWAYS requires matching BY DEFINITION. There is no alternative. ALL halfwave verticals and ALL fullwave dipoles demand matching. There are no commercial sources (transmitters) or lines that drive this kind of load directly, matching is the ONLY choice. A dipole offers a standard of gain. Anything can be adopted as a standard to compare to so this is a non runner. This attitude is self-serving. The dipole is the de-facto standard barring the isotropic specification. Choose one or the other, there is no honest third choice. The parallel circuit offers no change in gain except the prospect of reducing it through making the antenna smaller to become a resonant system. As a dipole moves away from its resonant point gain losses occur, I have shown this to be false. A parallel circuit double that danger by offering hazardous potentials at both its tips and its drive point. Should be zero change in drive point at the antenna input port and should provide less voltage hazards as it would tend to lower voltages and increase current which is the prime requirement for radiation. This point is one of the main points I fail to understand why the group will not embrace. Because it is not true. A parallel resonant circuit BY DEFINITION has a high Z characteristic. A constant power (which is to say the same power you would put into a low Z characteristic, series resonant antenna) drives the voltage to hazardous levels. There is no other outcome. 73's Richard Clark, KB7QHC |
aunwin wrote:
Yup, Richard you got me fair and square. I really thought that this discussion was going to be fruitful and pushed aside all past history. Art, one thing to remember is that if you are going to need a transmission line anyway, you might as well let it do the matching. A one-wavelength dipole fed with 1/4WL of open-wire line is a pretty good match to coax. -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
Art,
Will a parallel circuit radiate? Yes. Will it have a reasonable input impedance? Depends on what you call 'reasonable'. If you mean a 50 ohm input impedance, then the answer's not likely! Thanks for the help offer but I don't need it. 'Doc PS - I was thinking for my self. No one asked me to think for them. |
"aunwin" wrote in message news:Zf92c.186983$uV3.785337@attbi_s51...
Yup, Richard you got me fair and square. I really thought that this discussion was going to be fruitful and pushed aside all past history. Just shows how dumb I am..But then I am sure I will not be the last one to be taken in. You really executed the situation well Art Why do you consider it non-fruitful? Because the answers didn't fit the "program"? Seems to me, he answered all your questions quite plainly and without obvious error. BTW, I DO consider a matching device to be part of the antenna, if one is required. Go buy a storebought yagi, 1/2 vertical, etc, etc.. All will include the matching device as part of the deal. I've never seen any charge extra. I've built many base fed 1/2 waves. All including a matching device as part of the antenna. No, it's not the radiating element, but I still consider it part of the antenna. Without it, you have a non fuctioning piece of metal if you want to feed it with a 50 ohm radio, and feedline. MK |
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