|
Three short simple questions about antennas
Why must only series circuits be considered for radiators?.
What is it about parallel circuits that make them unsuitable? Is stagger tuning a parallel circuit ? Regards Art |
Art KB9MZ wrote:
"Why must only series circuits be considered for radiators?" It is convenient to follow custom. Art also wrote: "What is it about parallel circuits that make them unsuitable?" We are more familiar with impedance than admittance in most cases due to our instruction. A parallel resonsant circuit is a high impedance (low admittance). A series resonant circuit is a low impedance (high admittance). For a parallel circuit, Q=R/X. For a series circuit, Q=X/R. The series circuit has its equivalent parallel circuit. The parallel circuit has its equivalent series circuit. The mathematical conversion from one to the other is simple and shown in my 19th edition of the ARRL Antenna Book on page 24-12. (By coincidence the action of 1//4-wave and 1/2-wave transmission line sections is shown on the next page, 24-13) Commentors on using a 1/2-wave of foreign line inserted in a 50-ohm system, and what the ITT Handbook says should consult the Antenna Book or some other book that not only gives you the basic information but also tells you how to use the information. Best regards, Richard Harrison, KB5WZI |
Art, KB9MZ also wrote:
"Is stagger tuning a parallel circuit?" Stagger tuning is two or more resonant circuits each tuned to a different frequency. No restriction that I know of requires parallel resonance. You can mix and match. Best regards, Richard Harrison, KB5WZI |
On Thu, 04 Mar 2004 18:18:46 GMT, "aunwin"
wrote: Why must only series circuits be considered for radiators?. Hi Art, I don't know if there's a "must" to this. Every series circuit can be seen as a parallel circuit; and on the flip side, every parallel circuit can be seen as a series circuit. It is all a matter of where you put your leads to drive/measure/load/receive.... The same components vary only slightly in frequency from their being series resonant or parallel resonate. Without that drive/measure/load/receive path, there is no energy transfer and power consumption is all strictly a matter of component ohmic loss. What is it about parallel circuits that make them unsuitable? They are used every day to load up halfwave verticals, which in turn are also parallel equivalent circuits. The input to the parallel interface is performed through divider action (usually a tapped coil, but could be through a capacitor divider). Is stagger tuning a parallel circuit ? No, but it could be. Stagger tuning, by convention is a chain of separately tuned circuits, be they RC, RL, or LC (or, of course RLC). One RC or RL circuit exhibits a 6dB/Octave or 10dB/Decade roll-off. One LC circuit exhibits twice that or a 12dB/Octave or 20dB/Decade roll-off. Again, it is all a matter of connections for the identical components (which will show a slight shift in parallel to series resonance frequency - which is to say it is application dependent). Two RC or two RL, or one RC with one RL in cascade constitute "stagger tuning" irrespective of what frequencies their roll-off occur at (this sets the stage for Bandwidth) and their sum contribution equal roughly one LC circuit (which does not qualify as "stagger tuned") as long as they share the same characteristic frequency (where the roll-off occurs which is generally defined at the 3dB inflection). Now, as to the expression "roll-off" used liberally above. All such circuits may be called "de-emphasis" (where roll-off is evident) or "pre-emphasis" (where roll-up would be more descriptive). The application is strictly a matter of where the drive is applied, and where the load takes its output. 73's Richard Clark, KB7QHC |
This is silly......... and you can't blame this on web tv. Not one answer to any of the questions that anybody can hang their hat on!, Just talking out loud from a book that fell open at a page. When are you going to make some sense with your responses, most of us know and use the formulas that you keep regurgitating but only when they are relavent. Did your posting get cut short and the answers destroyed or did you forget why you are posting? There are three simple questions only. Simple answers should suffice............. if........ you know your stuff. If you find the answers to the simple questions in a book then please let me know and I can read it in context for myself and I will thank you.. When Johny Carson gave the answers first on his show and one then had to find a suitable question for it it was funny first time around only, so you should quit doing it. If you don't know the answers then it O.K. you don't have to respond if you don't know, certainly better than verbal diarrea. Art "Richard Harrison" wrote in message ... Art KB9MZ wrote: "Why must only series circuits be considered for radiators?" It is convenient to follow custom. Art also wrote: "What is it about parallel circuits that make them unsuitable?" We are more familiar with impedance than admittance in most cases due to our instruction. A parallel resonsant circuit is a high impedance (low admittance). A series resonant circuit is a low impedance (high admittance). For a parallel circuit, Q=R/X. For a series circuit, Q=X/R. The series circuit has its equivalent parallel circuit. The parallel circuit has its equivalent series circuit. The mathematical conversion from one to the other is simple and shown in my 19th edition of the ARRL Antenna Book on page 24-12. (By coincidence the action of 1//4-wave and 1/2-wave transmission line sections is shown on the next page, 24-13) Commentors on using a 1/2-wave of foreign line inserted in a 50-ohm system, and what the ITT Handbook says should consult the Antenna Book or some other book that not only gives you the basic information but also tells you how to use the information. Best regards, Richard Harrison, KB5WZI |
"aunwin" wrote in message news:aqK1c.176934$jk2.646180@attbi_s53... Why must only series circuits be considered for radiators?. They aren't. Series circuits are series circuits , radiators are radiators. They are different things. What is it about parallel circuits that make them unsuitable? Suitable for what? Is stagger tuning a parallel circuit ? Regards Art This question needs to be finished. A parallel circuit can't be stagger tuned. Troll?? -- Steve N, K,9;d, c. i My email has no u's. |
"Richard Clark" wrote in message ... On Thu, 04 Mar 2004 18:18:46 GMT, "aunwin" wrote: Why must only series circuits be considered for radiators?. Hi Art, I don't know if there's a "must" to this. At last.... at last somebody said 'I don't know' Perhaps Walter will now say he doesn't know! Every series circuit can be seen as a parallel circuit; and on the flip side, every parallel circuit can be seen as a series circuit. It is all a matter of where you put your leads to drive/measure/load/receive.... The same components vary only slightly in frequency from their being series resonant or parallel resonate. Without that drive/measure/load/receive path, there is no energy transfer and power consumption is all strictly a matter of component ohmic loss. Yes, partially understood , so to the question...... What is it about parallel circuits that make them unsuitable? They are used every day to load up halfwave verticals, which in turn are also parallel equivalent circuits. Did you mean that? A halfwave vertical is a parallel circuit! The input to the parallel interface is performed through divider action (usually a tapped coil, but could be through a capacitor divider). Yes I know that but the question did say antennas didn't it? You gave an answer to a question that was not asked. What you are refering to is not for its radiation attributes is it? I hope we are not going into a multi heading thread mode in less than 12 hours. Is stagger tuning a parallel circuit ? No, but it could be. Stagger tuning, by convention is a chain of separately tuned circuits, be they RC, RL, or LC (or, of course RLC). You mentioned the all important word of "tuned" so all of the above are parallel circuits....right? One RC or RL circuit exhibits a 6dB/Octave or 10dB/Decade roll-off. One LC circuit exhibits twice that or a 12dB/Octave or 20dB/Decade roll-off. Again, it is all a matter of connections for the identical components (which will show a slight shift in parallel to series resonance frequency - which is to say it is application dependent). I totally miss this point and probably the blame is mine. I think you are saying that yes, they are parallel circuits, but you have an exception that you want to point out i.e.slight shift in parallel to series........... Not sure if you are saying 'yes'. I personaly think it is a parallel circuit to which I would answer 'yes'. Are you asking for some wriggle room? Two elements that are physically separated is much too hard for me to describe as a series circuit. So I ask the question in the context of the first two questions to prevent answers to the like of 'just habit.' Now I am not being awkward, believe me or I would not have responded. Force 12 has stagger tuning, if it is series devised then it gives more ammo to the 'do not use parallel circuits for antennas' argument which seems to be prevalent with antenna experts. Two RC or two RL, or one RC with one RL in cascade constitute "stagger tuning" irrespective of what frequencies their roll-off occur at (this sets the stage for Bandwidth) and their sum contribution equal roughly one LC circuit (which does not qualify as "stagger tuned") as long as they share the same characteristic frequency (where the roll-off occurs which is generally defined at the 3dB inflection). Now, as to the expression "roll-off" used liberally above. All such circuits may be called "de-emphasis" (where roll-off is evident) or "pre-emphasis" (where roll-up would be more descriptive). The application is strictly a matter of where the drive is applied, and where the load takes its output. I lost the point that you had in mind with the above and I wish you had not mentioned bandwidth since it will bring another fork to the thread 73's Richard Clark, KB7QHC No rudeness intended anywhere Rich.. I seriously need reasonable specific answers before I spend a lot of money. Art |
Steve, ask me what you want to know about the posting. I am trying to keep
it short and to the point so I assumed ,maybe wrongly, that most were conversant with antennas. The shorter the question the less mucking around and surely, only an expert can provide the answers. Regards Art "Steve Nosko" wrote in message ... "aunwin" wrote in message news:aqK1c.176934$jk2.646180@attbi_s53... Why must only series circuits be considered for radiators?. They aren't. Series circuits are series circuits , radiators are radiators. They are different things. What is it about parallel circuits that make them unsuitable? Suitable for what? Is stagger tuning a parallel circuit ? Regards Art This question needs to be finished. A parallel circuit can't be stagger tuned. Troll?? -- Steve N, K,9;d, c. i My email has no u's. |
Richard I am reading your posts because I initiated the post
So for you I will pose it differently so you can quote from all your books legitimately. For you just one question only so you don't wander off as you sometimes do. And yes I will respond because I initiated the thread,yes I will read it. If radio was just thought of today give the pros and cons between a series circuit and a parallel circuit from which to base a radiator ? Don't put down 'tradition' or 'habit' just put a list of pro's and con for each side . 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. Keep it simple, don't twist the question around because you know of a special case. Just simple pro and con and you can quote from a book if it provides specific pro and con which will keep things in perspective i.e we know the formulae so there is no need to give your fingers a workout. 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? There, I am giving you the benefit of being a antenna guru that has the personal knoweledge that the question obviously requires and where a lot of people are hopelessly adrift. The question now is a bit long but hopefully for you it will be beneficial. Art "Richard Harrison" wrote in message ... Art, KB9MZ also wrote: "Is stagger tuning a parallel circuit?" Stagger tuning is two or more resonant circuits each tuned to a different frequency. No restriction that I know of requires parallel resonance. You can mix and match. Two circuits each with a different frequency will couple to each other via back EMF and thus makes it a parallel circuit. You can call it under coupled, over coupled or just coupled but it is a parallel circuit none the less. But let's not get side tracked because you don't know......'restrictions" just factual pro and con or you will wander off again. Art Best regards, Richard Harrison, KB5WZI |
On Thu, 04 Mar 2004 21:36:22 GMT, "aunwin"
wrote: What is it about parallel circuits that make them unsuitable? They are used every day to load up halfwave verticals, which in turn are also parallel equivalent circuits. Did you mean that? A halfwave vertical is a parallel circuit! 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). The input to the parallel interface is performed through divider action (usually a tapped coil, but could be through a capacitor divider). Yes I know that but the question did say antennas didn't it? Antennas don't find much application without some method of driving them. Very few successful halfwave designs exist without matching. This is because the halfwave vertical, looking like a parallel circuit, has a considerable amount of Z that rejects power (unless your rig is a van-de-graff generator). Adding the radiation resistance to a high Z hardly allows any current into the radiation resistance. On the other hand, a quarterwave looks like a series resonant circuit with very low Z, and thus the radiation resistance absorbs all the power applied. Very simple electronics. One solution to feeding the halfwave tall vertical is to break it in half and feed it half way up (where the two sections look like series resonant, low Z elements feeding the radiation resistance without much impediment). This is simplified, of course, but it illustrates how the same circuit can support either a series resonant or parallel resonant description determined only by the topology of connection. You gave an answer to a question that was not asked. What you are refering to is not for its radiation attributes is it? I hope we are not going into a multi heading thread mode in less than 12 hours. 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. Is stagger tuning a parallel circuit ? No, but it could be. Stagger tuning, by convention is a chain of separately tuned circuits, be they RC, RL, or LC (or, of course RLC). You mentioned the all important word of "tuned" so all of the above are parallel circuits....right? No, but they could be. The application of drive and loads determine the topology: One RC or RL circuit exhibits a 6dB/Octave or 10dB/Decade roll-off. One LC circuit exhibits twice that or a 12dB/Octave or 20dB/Decade roll-off. Again, it is all a matter of connections for the identical components (which will show a slight shift in parallel to series resonance frequency - which is to say it is application dependent). I totally miss this point and probably the blame is mine. I think you are saying that yes, they are parallel circuits, but you have an exception that you want to point out i.e.slight shift in parallel to series........... No, they are NOT parallel - they could be, but there is nothing inherently parallel and it all depends on the drive and load applied. 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. Force 12 has stagger tuning, if it is series devised then it gives more ammo to the 'do not use parallel circuits for antennas' argument which seems to be prevalent with antenna experts. Force 12 makes many antennas, I will presume you are speaking of some beam array. Stagger tuning, in that sense, is much akin to the reflector, radiator, director relationship of the yagi. That design is stagger tuned, but such stagger tuning is to accomplish various delays that aid gain in one direction, and negate it in another. Such stagger tuning is not directly engaged upon for the purpose of bandwidth, although it may have indirect consequences. I have a beam array for 440 that employs an LPDA radiator tied into the conventional reflector and directors. As such it performs stagger tuning for the purpose of beam forming AND bandwidth. The elements in the Fan Dipole or the Log Periodic Dipole Array more closely align to the conventional meaning of stagger tuning. The Fan Dipole is the most obvious case. It's metaphor would be as many parallel, series resonant circuits as there are elements, each slightly tuned off from the other, all feeding in series and combining in parallel to average a wider bandwidth response than any single series resonant element. 73's Richard Clark, KB7QHC |
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. The parallel circuit offers loss to an already most efficient antenna. A dipole is simple to load and often requires no matching. The parallel circuit is difficult to load and always requires matching. A dipole offers a standard of gain. The parallel circuit offers no change in gain except the prospect of reducing it through making the antenna smaller to become a resonant system. A dipole is a simple construction. The parallel circuit adds complexity which raises the prospects of mechanical and electrical failure. A dipole offers hazardous potentials at its tips. A parallel circuit double that danger by offering hazardous potentials at both its tips and its drive point. A dipole requires isolation/insulation at its tips due to high potentials. 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 |
Thank you ,thank you Richard.
I now have something to think about as to why I have been so misdirected these past few years where everybody knew I was wrong and I have yet to reason why. That is why I hoped only experts would respond after seeing the response to Reg on another thread. Get back to you later if I see the serious difference of thought that exists between myself and others regarding where and why I am out in 'left field' (Baseball talk Reg). Hopefully some other experts will contribute with statements that are specific, to the point and beyond question that may bring to light some bogies that are messing me up. Best regards Art "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. The parallel circuit offers loss to an already most efficient antenna. A dipole is simple to load and often requires no matching. The parallel circuit is difficult to load and always requires matching. A dipole offers a standard of gain. The parallel circuit offers no change in gain except the prospect of reducing it through making the antenna smaller to become a resonant system. A dipole is a simple construction. The parallel circuit adds complexity which raises the prospects of mechanical and electrical failure. A dipole offers hazardous potentials at its tips. A parallel circuit double that danger by offering hazardous potentials at both its tips and its drive point. A dipole requires isolation/insulation at its tips due to high potentials. 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 |
"Richard Clark" wrote in message ... On Thu, 04 Mar 2004 21:36:22 GMT, "aunwin" wrote: What is it about parallel circuits that make them unsuitable? They are used every day to load up halfwave verticals, which in turn are also parallel equivalent circuits. Did you mean that? A halfwave vertical is a parallel circuit! 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 input to the parallel interface is performed through divider action (usually a tapped coil, but could be through a capacitor divider). Yes I know that but the question did say antennas didn't it? Antennas don't find much application without some method of driving them. Very few successful halfwave designs exist without matching. This is because the halfwave vertical, looking like a parallel circuit, has a considerable amount of Z that rejects power (unless your rig is a van-de-graff generator). Adding the radiation resistance to a high Z hardly allows any current into the radiation resistance. On the other hand, a quarterwave looks like a series resonant circuit with very low Z, and thus the radiation resistance absorbs all the power applied. Very simple electronics. One solution to feeding the halfwave tall vertical is to break it in half and feed it half way up (where the two sections look like series resonant, low Z elements feeding the radiation resistance without much impediment). This is simplified, of course, but it illustrates how the same circuit can support either a series resonant or parallel resonant description determined only by the topology of connection. You gave an answer to a question that was not asked. What you are refering to is not for its radiation attributes is it? I hope we are not going into a multi heading thread mode in less than 12 hours. 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. Is stagger tuning a parallel circuit ? No, but it could be. Stagger tuning, by convention is a chain of separately tuned circuits, be they RC, RL, or LC (or, of course RLC). You mentioned the all important word of "tuned" so all of the above are parallel circuits....right? No, but they could be. The application of drive and loads determine the topology: One RC or RL circuit exhibits a 6dB/Octave or 10dB/Decade roll-off. One LC circuit exhibits twice that or a 12dB/Octave or 20dB/Decade roll-off. Again, it is all a matter of connections for the identical components (which will show a slight shift in parallel to series resonance frequency - which is to say it is application dependent). I totally miss this point and probably the blame is mine. I think you are saying that yes, they are parallel circuits, but you have an exception that you want to point out i.e.slight shift in parallel to series........... No, they are NOT parallel - they could be, but there is nothing inherently parallel and it all depends on the drive and load applied. 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 can be made to LOOK like several series circuits IF and Only IF one discardes the intercoupling factor, and I do not see how one can realistically refer to such an arrangement in any way as a quasi or something else with the term 'series' .. Force 12 has stagger tuning, if it is series devised then it gives more ammo to the 'do not use parallel circuits for antennas' argument which seems to be prevalent with antenna experts. Force 12 makes many antennas, I will presume you are speaking of some beam array. Stagger tuning, in that sense, is much akin to the reflector, radiator, director relationship of the yagi. That design is stagger tuned, but such stagger tuning is to accomplish various delays that aid gain in one direction, and negate it in another. Such stagger tuning is not directly engaged upon for the purpose of bandwidth, although it may have indirect consequences. Oh I will have to leave that for others to comment upon as that is not what I consider stagger tuning to be. I mentioned in another posting what I thought it to be, so obviously there are comments on the way to put me straight, hopefully in a factual way that puts the majority at ease. without a complication factor. I have a beam array for 440 that employs an LPDA radiator tied into the conventional reflector and directors. As such it performs stagger tuning for the purpose of beam forming AND bandwidth. The elements in the Fan Dipole or the Log Periodic Dipole Array more closely align to the conventional meaning of stagger tuning. The Fan Dipole is the most obvious case. It's metaphor would be as many parallel, series resonant circuits as there are elements, each slightly tuned off from the other, all feeding in series and combining in parallel to average a wider bandwidth response than any single series resonant element. I just don't understand what you are saying here, I must understand the parallel circuit part of a zepp or dipole part first to intellegently discuss all this other stuff you are talking about. The statements you are making on parallel versus series I view as enormous. Read the ARRL book on antennas and they dwell on series circuits as in dipole, why the big difference with this newsgroup? Your comments seem to rotate about phase changes more than it does about coupling as to the main focal point. No comments on your other posting yet .(pro and con) which suggest the experts are unified on your statements. 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 73's Regards Art Richard Clark, KB7QHC |
aunwin wrote:
Why must only series circuits be considered for radiators?. Just thinking out loud. I'm not sure I'm correct but the following seems to make a little sense. In a series resonant circuit the net reactance is zero. As the frequency is changed slightly from resonance the reactance increases slowly from zero. This is algebraic addition of plus and minus terms. In a parallel circuit the net reactance is the product of the two terms divided by the sum [and has a high net value]. As the frequency is changed slightly from resonance the net reactance does not change from 'zero' it changes from a high value to a lower value. My conclusion is that a series circuit more closely matches actual antenna performance as the antenna impedance varies from resonance. DD SNIPPED |
Hi David
Not sure what you are getting at. You can set up a parallel circuit that can be resonant on any frequency with minor change to its construction ala a slight inductance change so there is no need to operate on a non resonant frequency which is what I see as a huge plus. Remember I view the parallel circuit in its macro sense in that it is the radiator.My antennas work that way and computor programs seem to agree with that position. Can you supply a circuit in radiator form that acts as you describe so I can see how it differs ? Appreciate the input as there are only a few real experts and none have sort to disagree which is a first for this group. Kudoes to you and Richard who are able to provide honest thought here others are stumped. Regards Art "Dave Shrader" wrote in message news:aJR1c.45282$PR3.917056@attbi_s03... aunwin wrote: Why must only series circuits be considered for radiators?. Just thinking out loud. I'm not sure I'm correct but the following seems to make a little sense. In a series resonant circuit the net reactance is zero. As the frequency is changed slightly from resonance the reactance increases slowly from zero. This is algebraic addition of plus and minus terms. In a parallel circuit the net reactance is the product of the two terms divided by the sum [and has a high net value]. As the frequency is changed slightly from resonance the net reactance does not change from 'zero' it changes from a high value to a lower value. My conclusion is that a series circuit more closely matches actual antenna performance as the antenna impedance varies from resonance. DD SNIPPED |
aunwin wrote:
Not sure what you are getting at. Well, how about this, Art? A 1/2WL dipole is similar to a series circuit, i.e. low resistance increasing to each side. A one wavelength dipole is similar to a parallel circuit, i.e. high resistance decreasing to each side. -- 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! =----- |
Thanks for responding Cecil I know that you can't be intimidated
to say something that you disagree with. Now the dipole, arrangement doesn't change as you change in length. Well, put it another way, I need more input than that for me to ride on the same train with confidence. At the moment I am losing total confidence in myself because of the unity of others in thought that opposes mine. Especially when some are much better educated than I. But then you said SIMILAR, you did NOT say it changed to parallel, so I can agree with 'similar' when comparing a particular characteristic Cheers Art "Cecil Moore" wrote in message ... aunwin wrote: Not sure what you are getting at. Well, how about this, Art? A 1/2WL dipole is similar to a series circuit, i.e. low resistance increasing to each side. A one wavelength dipole is similar to a parallel circuit, i.e. high resistance decreasing to each side. -- 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, KB9MZ wrote:
"Well that is news to me. I never consider the matching circuit as part of an antenna, but only a required band aid." Art only recently changed his mind it seems. A year or so ago he was arguing that the tuned T-matched arrangement he claimed to have invented added gain from its radiation to that of his dipole. I said , "impossible because radiation from a small loop is directed in the plane of the loop." So Art hates me. More recently we discussed current distribution on short loaded vertical antennas and if current had to be the same at both ends of a loading coil. It doesn`t. Yuri presented in evidence Fig 9-22 from page 9-15 of the 2nd edition of ON4UN`s "Low-Band DXing". Art shows disdain for experts and books, so he may have paid no attention or quickly forgot. One of the six examples in ON4UN`s figure is a continuously loaded radiator. No doubt, no matter how feeble it is, the radiation emanates from the loading coil which comprises the entire antenna. Richard Clark was showing that the choice of series resonant or parallel resonant as a model may be based on application or impedance. A parallel resonant circuit exhibits high impedance. It is used for high isolation as a trap, and as a phase inverter for a collinear as in the self-resonant coil from Kraus presented by Cecil. A parallel resonant circuit is also used to match end-fed 1/2-waves and similar high impedance antennas. Many cheap small radios just connect the high impedance antenna to to the hot end of the tank circuit. The J-pole drives an end-fed 1/2-wave antenna from a short-circuited 1/4-wave stub. The stub is equivalent to a parallel resonant circuit and exhibits a high impedance at its open-circuit end. This was another of Richard Clark`s examples. I regret Art fails to see the relevance of much of the accurate information offered. Best regards, Richard Harrison, KB5WZI |
Steve Troll?? Yes, troll. 'Doc |
Richard you have started to wander again. If a matching unit is used for
matching input inpedance of a radiator and not for the purpose of radiating then it is certainly not part of the antenna. If the radiating circuit has some lumped loads on it which can be varied in value then that is certainly part of the antenna. Try and stay focussed. Regards Art "Richard Harrison" wrote in message ... Art, KB9MZ wrote: "Well that is news to me. I never consider the matching circuit as part of an antenna, but only a required band aid." Art only recently changed his mind it seems. A year or so ago he was arguing that the tuned T-matched arrangement he claimed to have invented added gain from its radiation to that of his dipole. I said , "impossible because radiation from a small loop is directed in the plane of the loop." So Art hates me. More recently we discussed current distribution on short loaded vertical antennas and if current had to be the same at both ends of a loading coil. It doesn`t. Yuri presented in evidence Fig 9-22 from page 9-15 of the 2nd edition of ON4UN`s "Low-Band DXing". Art shows disdain for experts and books, so he may have paid no attention or quickly forgot. One of the six examples in ON4UN`s figure is a continuously loaded radiator. No doubt, no matter how feeble it is, the radiation emanates from the loading coil which comprises the entire antenna. Richard Clark was showing that the choice of series resonant or parallel resonant as a model may be based on application or impedance. A parallel resonant circuit exhibits high impedance. It is used for high isolation as a trap, and as a phase inverter for a collinear as in the self-resonant coil from Kraus presented by Cecil. A parallel resonant circuit is also used to match end-fed 1/2-waves and similar high impedance antennas. Many cheap small radios just connect the high impedance antenna to to the hot end of the tank circuit. The J-pole drives an end-fed 1/2-wave antenna from a short-circuited 1/4-wave stub. The stub is equivalent to a parallel resonant circuit and exhibits a high impedance at its open-circuit end. This was another of Richard Clark`s examples. I regret Art fails to see the relevance of much of the accurate information offered. Best regards, Richard Harrison, KB5WZI |
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 |
No Cecil it is not about transmission lines it is about a parallel circuit
that radiates. Most of this group are Americans so they all read a book for a formula that might fit what we are talking about. One trots out a simple formula for the Q of a parallel circuit and yells Eureeeeeka and they all follow like Lemmings hooking themselves on this formula that they found in a book. It is a really simple formula but did anybody think for themselves? Ofcourse they didn't, its a simple formula so all that is needed is to parrot it out and follow people who yell loudly that they know what they are talking about. Roy and Shakespeare started it off years ago, yes Wes and many others followed suit and Walter, well he said nothing. Now I ask you Cecil they trot out this formula for Q, it is in books so they feel safe or it would not be in a book right? Now I ask you Cecil if you make an antenna array and you decide that you require an input Z for this array what other values do you need for this very simple formula bearing in mind that is a parallel circuit containing a capacitor of unknown value a inductance of unknown value and then come up with an air of knoweledge. Isn't it crazy ? On top of all that they use a formula that is in a book without determining where it comes from and what it is relevant to and what the simple values represent. Reg saw the problem a long while ago but I think he looked to the sky, shook his head and maybe snickered to himself. I am sure he knows that when you use a formula you can't pick and choose what you insert in a formula. If you are thinking impedance, resistance or whatever and you have a huge physical circuit that contains yards and yards of members that radiate as well as connecting to other passive circuits one would figure that these radiating members would have an impact on this simple circuit that was in a book. And right from the beginning none of them know how long these members are and what diameter and the configuration is even tho they keep spewing their technical garbage because after all they are experts and thus they determine who is right or wrong, whether they be manufacturers, antenna designers or learning amateurs. So tell me Cecil the parallel circuit is in a book and for years I have tried to get people to think for themselves but they can't because this simple formula is in a book so any thinking goes out the window. I find it unbelievable that so many technical people this side of the pond did not even think of looking beyond a book that has this formula in it with only three components and not one thought about inserting figures into it and resolving things for themselves. Yup the idea of figuring out all those resistances was too much for them so they sat back and trotted out phrases from a book that referred to a simple bandpass circuit possibly the size of a finger nail and then sat back and said it was good enough for a 160 meter antenna as we can ignore the wire or radiating members up there as being inconsequential. I ask you Cecil as one who has also also bore the brunt of uneducated attacks what were they taught at school over here that allowed them to bandy this formula around without understanding what it means. No, don't tell me it is beyond anybody to provide a reasonable explanation all they care about is crowding around Madame Guilliotine and cheering as somebody gets killed. Gentlemen if I can call you that go now back to your books and figure out the pertinent figures that is needed for this simple formula and then think about all those nasty things you have said O and by the way remember you can add a shunt resistance if the impedance ratio gets a bit high but then you will have to go back to a book to find out where to put it, I could tell you but I will refrain, a couple of years to figure it out may be beneficial "Cecil Moore" wrote in message ... aunwin wrote: Not sure what you are getting at. Well, how about this, Art? A 1/2WL dipole is similar to a series circuit, i.e. low resistance increasing to each side. A one wavelength dipole is similar to a parallel circuit, i.e. high resistance decreasing to each side. -- 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! =----- |
On Sun, 07 Mar 2004 02:47:16 GMT, "aunwin"
wrote: Now I ask you Cecil .... Now I ask you Cecil .... So tell me Cecil .... I ask you Cecil .... the world wonders.... Hi Art, Waiting for the fresh mist of the mountain dell to grace your visage? ;-) Perhaps you can tell us what source (no books count) of your definition of Q? I doubt it was at the knee of lord plushbottom (a rather grisly prospect, eh what?). 73's Richard Clark, KB7QHC |
Art, KB9MZ wrote:
"It is really a simple formula so all that is needed is to parrot it out and follow people who yell loudly that they know what they know what they are talking about. Roy and Shakespeare started it off years ago, yes Wes and many others followed suit and Walter, well he said nothing. Now I ask you Cecil they trot out the formula for Q, it is in books so they feel safe or it would not be in a book right?" All the people Art mentiomned have contributed to this newsgroup and understood how things work. They`ve read the books, benefitted from the knowledge and its application. They are confident in the book knowledge from experience. They are real engineers who know what to use and how and when to use it. That`s different from the handbook experts who often blunder from shallow knowledge and lack of experience. Books are accumulated knowledge that allow us to exploit the experience of others so we don`t have to repeat all the mistakes. As for Q, it is a definition that simplifies formulas. The basis of Q is: the energy stored per cycle versus the energy lost per cycle. You can find that basic definition of Q in any number of books for yourself if you want to look it up. The people Art listed aren`t yelling loudly that: "they hnow what they know!" They are demonstrating their knowledge in their postings which explain andf quantify. Some have their fun too. Despite what Art posted, you can pick and choose what you insert in a formula. "What if" is one of the most rewarding games arounnd. Antenna programs are good examples. Best regards, Richard Harrison, KB5WZI |
"aunwin" wrote in message news:U2w2c.130951$4o.169497@attbi_s52...
No Cecil it is not about transmission lines it is about a parallel circuit that radiates. Where did he mention transmission lines? I thought he was comparing a 1/2 wave dipole to a full wave dipole as far as circuit description... Most of this group are Americans so they all read a book for a formula that might fit what we are talking about. All? I think not, Art... One trots out a simple formula for the Q of a parallel circuit and yells Eureeeeeka and they all follow like Lemmings hooking themselves on this formula that they found in a book. They did? I guess I missed it... It is a really simple formula but did anybody think for themselves? I can ONLY think for myself. I have failed to master the art of thinking for others... Ofcourse they didn't, its a simple formula so all that is needed is to parrot it out and follow people who yell loudly that they know what they are talking about. I have no idea what you are talking about... Roy and Shakespeare started it off years ago, yes Wes and many others followed suit and Walter, well he said nothing. I thought Shakespeare was an old fart that lived in England. How did he join this illustrious grouping of Americans? Now I ask you Cecil they trot out this formula for Q, it is in books so they feel safe or it would not be in a book right? Right? Now I ask you Cecil if you make an antenna array and you decide that you require an input Z for this array what other values do you need for this very simple formula bearing in mind that is a parallel circuit containing a capacitor of unknown value a inductance of unknown value and then come up with an air of knoweledge. Why are the values unknown? But even discarding that question, what is the big deal about designing a parallel circuit? I've done it many, many times. The formula for Q never even entered my skull. I really don't even need inductance or cap values. Why? Cuz I'm the wizard of burdine street....:/ I work from sense of smell. :) But I'll give you a hint as it applies to a base fed 10m 1/2 wave vertical. The usual cap value is appx 50 pf. Didn't need no stinkin formula to come up with that...Dang...I must surely be cracked to work the way I do... Isn't it crazy ? On top of all that they use a formula that is in a book without determining where it comes from and what it is relevant to and what the simple values represent. I'm curiuous...Who was the American that offered this formula for parallel circuits? I must have missed it. Reg saw the problem a long while ago but I think he looked to the sky, shook his head and maybe snickered to himself. I think Reg does that nearly every day. If the wine and "entertainment" is good, he may even snicker out loud... I am sure he knows that when you use a formula you can't pick and choose what you insert in a formula. If you are thinking impedance, resistance or whatever and you have a huge physical circuit that contains yards and yards of members that radiate as well as connecting to other passive circuits one would figure that these radiating members would have an impact on this simple circuit that was in a book. What simple circuit? What book? And right from the beginning none of them know how long these members are and what diameter and the configuration is even tho they keep spewing their technical garbage because after all they are experts and thus they determine who is right or wrong, whether they be manufacturers, antenna designers or learning amateurs. Why do we not know what diameter and the configuration is? Who's fault is this? So tell me Cecil the parallel circuit is in a book and for years I have tried to get people to think for themselves but they can't because this simple formula is in a book so any thinking goes out the window. Can we spell broke record? Art, again, I ONLY think for myself. You couldn't afford my price to think for you, or any others... I don't think for free. Besides, I don't need any extra leads or wiring coming out of my ears, mouth, or my other skull openings... I find it unbelievable that so many technical people this side of the pond did not even think of looking beyond a book that has this formula in it with only three components and not one thought about inserting figures into it and resolving things for themselves. I will find it amazing if anyone can understand what the heck you are harping about...Frankly, all this extended diatribe is confusing to most I think. Double so, if you are an ignorant redneck like me... Yup the idea of figuring out all those resistances was too much for them so they sat back and trotted out phrases from a book that referred to a simple bandpass circuit possibly the size of a finger nail and then sat back and said it was good enough for a 160 meter antenna as we can ignore the wire or radiating members up there as being inconsequential. As previously noted. It's hard to understand what the heck you are talking about. I remember no such thing ocurring...Thread name? I ask you Cecil as one who has also also bore the brunt of uneducated attacks what were they taught at school over here that allowed them to bandy this formula around without understanding what it means. Cecil was attacked? Did he survive? Did the formula survive? No, don't tell me it is beyond anybody to provide a reasonable explanation Ok, I won't... all they care about is crowding around Madame Guilliotine and cheering as somebody gets killed. http://www.stud.hh.se/org/hasp/02/gala/6.html I see them cheering and crowding around her, but I see no body... Gentlemen if I can call you that No, I'm a redneck. Most "gentlemen" shave their legs, and eat quiche energy bars... go now back to your books and figure out the pertinent figures that is needed for this simple formula Why? Will there be a test? and then think about all those nasty things Nasty? Whoa daddy, stand back....He's hurling a nasty... you have said O and by the way remember you can add a shunt resistance if the impedance ratio gets a bit high but then you will have to go back to a book to find out where to put it, He will? What if he doesn't own the book? I could tell you but I will refrain, a couple of years to figure it out may be beneficial Typical....What, is this some big dark secret? I think we should rename this group, rec.radio.peyton.place :/ MK |
Mark, From the following list, select all that apply. 1. There's a full moon. 2. "Don't know whether he's/I'm washing or hanging out." 3. "He's/I'm as lost as a ball in high weeds." 4. "Shazzam, Sargent Carter!" I've decided that Art is a force of nature, sort of like the tides. One minute it's coming in, the next minute it's going back out. I'm in the process of compiling a "Tide Table" for Art. The period is fairly predictable, it's the variations that are a bit tricky, haven't got a handle on all those, yet. Observations would be appreciated... 'Doc |
|
"aunwin" wrote in message news:aqK1c.176934$jk2.646180@attbi_s53... Why must only series circuits be considered for radiators?. The last discription I saw of a quarter wavw antenna was that of a paralell circuit. Isnt that basically how a capacity hat shortens an antenna, by increasing the paralell capacitance What is it about parallel circuits that make them unsuitable? Who says they are not. Is stagger tuning a parallel circuit ? This question being out of context with the other questions seems to indicate you really dont know what stagger tuning means so I dont know how to reply. Regards Art |
"Richard Harrison" wrote in message ... A parallel resonsant circuit is a high impedance (low admittance). est regards, Richard Harrison, KB5WZI Now go back to your books since your memory is poor and check out what restrictions apply. Do you ignore all connection lengths between lumped circuits. Do they say all parallel circuits ALWAYS have a high impedance without exception? Does this simple formula account for radiation ? Does a parallel circuit in macro form that radiates apply with respect to this simple formula regardless of interconnection lengths? Must all distributed passive forms be ignored and why? |
"Richard Harrison" wrote in message ... onant as a model may be based on application or impedance. A parallel resonant circuit exhibits high impedance. Read what the book says about circuits that exhibit high impedance and what the formula omits as being inconsequential With reference to a large radiating parallel circuit containing both distributed and lumped passive circuits figure out what the numbers are that you can or can not place in the simple circuit that proves your point. I regret Art fails to see the relevance of much of the accurate information offered. Best regards, Richard Harrison, KB5WZI |
Jimmy wrote:
"The last description I saw of a quarter wave antenna was that of a parallel circuit. Isn`t that basically how a capacity hat shortens an antenna, by increasing the parallel capacitance?" Parallel or series hardly makes any difference. The 1/4-wave antenna is essentially a 1/2-wave antenna with the missing 1/4-wave piece replaced by a ground reflection. Terman illustrates current distribution in a doublet on page 866 of his 1955 edition. He says: "These current distributions are those that would be obtained by applying the exciting voltage in series with the wire at a current loop, or to one end of the wire." The series representation is conventional and comes from the distributed nature of resistance, inductance, and capacitance along the antenna wire. From the generator or transmission line`s point of view, it may be more convenient to view the antenna load as a parallel resonant circuit. Parallel or series circuit, they are mathematically interchangeable by using conversion formulas which appear in various books including the ARRL Antenna Book. Use whichever form you like. There is a difference between a length of wire and a tank circuit. The wire has multiple harmonically related resonances. The tank circuit does not. It has only one resonance. Jimmy also wrote: "Who says they are not (parallel circuits suitable to model an antenna)?" Yes, Art Unwin, who says they are not? Jimmy also wrote: "This question (is stagger tuning a parallel circuit?) being out of context with the other questions seems to indicate you really don`t know what stagger tuning means so I don`t know how to reply." Art for years has hijacked threads to advertise a tuned loop conjoined with a dipole. One of his claims is that the loop is tuned to one frequency and the dipole is tuned to a different frequency ergo a broadband antenna is produced. You must guess between the lines to make sense of what Art says. Best regards, Richard Harrison, KB5WZI |
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