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Current across the antenna loading coil - from scratch
Cecil Moore wrote:
John Popelish wrote: Cecil Moore wrote: That is not what the formula says. Pick and X and you get a constant phase angle with respect to the zero degree reference. But that phase angle is not zero as it is for standing waves. You seem to be talking in circles. How can the phase shift between the traveling wave and the source reference ever be zero at a point 90 degrees away from the source? I said the phase was was fixed, not zero, at a given position. If it cannot, then you have evidence that the traveling wave is NOT identical to the standing wave as evidenced by their different equations. I agreed that the pattern of amplitude and phase is different along a line for traveling and standing waves. But at any given point, there is a very similar kind of phasor ( one with an amplitude value and a phase value) that describes what is happening at that point. That difference in amplitude distribution and phase shift with respect to position is what the two functions describe. You keep claiming that there is something fundamentally different about the kind of phasor describing a single point (rotating versus non rotating), depending on whether the phasor is describing a point on a standing or traveling wave. That is where we disagree. Let's cut to the bottom line. You seem to believe that standing wave current is identical to traveling wave current. At a point, it certainly can be. How current varies (amplitude and phase) over length is what is different. If that's your point, just say so. I have said so as emphatically as I can, at least a half dozen times. You keep saying I am wrong and refer to rotating phasors and non rotating phasors. The only rotating phasor I know if is when a different (from the reference frequency and phase) frequency is described by phasor notation. That phasor rotates. Otherwise, please tell us the difference between the standing wave current and the traveling wave current which seems obvious to me from the equations. I have, already. But here goes once again. A current produced by a traveling wave has a constant (RMS) amplitude along the line. The phase of the current (relative to some arbitrary phase reference) varies linearly along the line. If the line is a wavelength or more long, you can find any relative phase you want, just by moving along the line. There is energy moving along the line during this process, but no net (averaged over a cycle) current moving along the line. this is similar to how wave energy moves along the surface of water, without the water traveling along with the wave. The water just moves up and down as the wave passes along its surface. Likewise, charge moves back and forth, locally, within a half wavelength of the line as the wave passes, and the local current is a measure of the rate of this charge movement. In the case of a pure standing wave, you have the super position of two equal and opposite traveling waves. The current (RMS) magnitude can vary anywhere from zero to twice the (RMS) magnitude of that produced by either of the two traveling waves. The RMS amplitude envelope will vary in a [absolute value of sine] way along the line. The relative phase of the current will have one of two values (the actual angle depending on what phase is chosen as the reference) that are 180 degrees apart. The phase switches between these two values each time you pass through a node in the amplitude distribution. There is no net energy movement, since the movement in one direction is canceled by energy movement in the other direction. There is, however, energy storage on the line. Since the charge movement in a standing wave is the superposition of the charge movement of two traveling waves, in a standing wave, charge also moves back and forth only within a half wavelength interval of the line. And the standing wave current is the measure of the rate of change in this charge movement as it sloshes back and forth within that half wavelength. If you have any corrections to any of this, please quote enough of what you what you are correcting for the context to be clear, and have at it. I want to get this right. |
Current across the antenna loading coil - from scratch
Cecil Moore wrote:
EZNEC clearly recognizes the difference between standing wave current and traveling wave current. Yet you tried to use standing wave current with its unchanging phase to measure the phase shift through a coil. Standing wave current doesn't even change phase through 45 degrees of wire. Why would you expect it to change phase through 45 degrees of coil? Not to be a stickler, but didn't you just chastise me for bringing up coils, and you said you had no interest in discussing them, because that subject was closed for you? Make up your mind, please. |
Current across the antenna loading coil - from scratch
John Popelish wrote:
Cecil Moore wrote: EZNEC clearly recognizes the difference between standing wave current and traveling wave current. Yet you tried to use standing wave current with its unchanging phase to measure the phase shift through a coil. Standing wave current doesn't even change phase through 45 degrees of wire. Why would you expect it to change phase through 45 degrees of coil? Not to be a stickler, but didn't you just chastise me for bringing up coils, and you said you had no interest in discussing them, because that subject was closed for you? Make up your mind, please. And in any case, the statement about EZNEC is incorrect. As I explained in a posting a short while ago, EZNEC has no awareness of nor does it make any use of traveling wave currents or voltages. It calculates only the total current from fundamental rules which don't involve traveling waves. Roy Lewallen, W7EL |
Current across the antenna loading coil - from scratch
Cecil Moore wrote:
wrote: Grow up Cecil. Everyone sees what you are doing. Everyone should see that I am trying to discuss technical issues while the rest of you object to the 5% of my postings that are bad humor or complaints about how I am being unfairly treated. Why do you refuse to discuss technical issues? For instance, you have avoided responding to my black box question. Are you afraid everyone will see just how wrong you are? No one likes a whiner Cecil. Especially when they appear to be ****ing into the wind. tom K0TAR |
Current across the antenna loading coil - from scratch
On Tue, 04 Apr 2006 21:18:53 -0400, John Popelish
wrote: Make up your mind, please. The triumph of experience over hope. |
Current across the antenna loading coil - from scratch
On Tue, 04 Apr 2006 19:34:19 GMT, Cecil Moore
wrote: Here is it again assuming a lossless transmission line: Source-----------a-BB-b-------------c-BB-d-----------open The current measured at 'a' is one amp. The current measured at 'b' is zero amps. The current measured at 'c' is zero amps. The current measured at 'd' is one amp. What are the possibilities for what could be in the black boxes? There is a zero length 4th dimensional coax connecting ad and bc bridging the Casimir void between b and c. Can you deny the 4th dimension exists? |
Current across the antenna loading coil - from scratch
John Popelish wrote:
I said the phase was was fixed, not zero, at a given position. So the phase is NOT the same between the standing waves and the traveling waves proving that standing waves are different from traveling waves. Like I said, we seem to be going in circles. I agreed that the pattern of amplitude and phase is different along a line for traveling and standing waves. Then why are you arguing with me about it. That's what I also believe. Your argument seems to be with the people who say, "current is current". You keep claiming that there is something fundamentally different about the kind of phasor describing a single point (rotating versus non rotating), depending on whether the phasor is describing a point on a standing or traveling wave. That is where we disagree. Yes, 45 degrees is fundamentally different from zero, is it not? Let's see, the percentage difference is (45-0)/0. Let's cut to the bottom line. You seem to believe that standing wave current is identical to traveling wave current. At a point, it certainly can be. No it isn't. It is the lack of knowledge that causes one to assume that. More knowledge is all it takes to tell the difference. If the current is everywhere in phase with the source current, it is standing wave current. If the current is only in phase with the source current every 360 degrees, it is traveling wave current. If you have any corrections to any of this, please quote enough of what you what you are correcting for the context to be clear, and have at it. I want to get this right. We seem to be in basic agreement that traveling wave current is not identical to standing wave current so what are we arguing about? -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
John Popelish wrote:
Cecil Moore wrote: EZNEC clearly recognizes the difference between standing wave current and traveling wave current. Yet you tried to use standing wave current with its unchanging phase to measure the phase shift through a coil. Standing wave current doesn't even change phase through 45 degrees of wire. Why would you expect it to change phase through 45 degrees of coil? Not to be a stickler, but didn't you just chastise me for bringing up coils, and you said you had no interest in discussing them, because that subject was closed for you? Make up your mind, please. My comment above is primarily about standing wave current, not about coils. Standing wave current phase cannot be used to measure the phase shift through empty space, wires, or anything else. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
Roy Lewallen wrote:
And in any case, the statement about EZNEC is incorrect. As I explained in a posting a short while ago, EZNEC has no awareness of nor does it make any use of traveling wave currents or voltages. It calculates only the total current from fundamental rules which don't involve traveling waves. EZNEC reports a different phase for traveling wave currents than it does for standing wave currents. It does know the difference although I don't know how it knows. It recognizes the difference between a terminated line with no reflections and an unterminated line with reflections. The current reported by EZNEC for a terminated rhombic, for instance, is clearly traveling wave current since the phase changes with distance from the source. The current reported by EZNEC for a 1/2WL dipole, for instance, is clearly standing wave current since the phase doesn't change with distance from the source. The two kinds of currents are clearly not identical in either EZNEC or in reality. They are only identical in some human minds. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
Tom Ring wrote:
No one likes a whiner Cecil. Then please stop whining. :-) -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
Cecil Moore wrote:
My comment above is primarily about standing wave current, not about coils. Standing wave current phase cannot be used to measure the phase shift through empty space, wires, or anything else. Sure it can. You just haven't yet figured out how to do it. Here is a hint. Standing wave current and voltage is not all the same phase. Go far enough down the line, and there is a change. How far is far enough? |
Current across the antenna loading coil - from scratch
John Popelish wrote:
Cecil Moore wrote: Standing wave current phase cannot be used to measure the phase shift through empty space, wires, or anything else. Sure it can. You just haven't yet figured out how to do it. Here is a hint. Standing wave current and voltage is not all the same phase. Go far enough down the line, and there is a change. How far is far enough? My comment above is about 1/2WL dipoles and 1/4WL monopoles. In those antennas, the standing wave current phase is fixed around zero degrees. It cannot be used to measure delay through anything. The 180 degree phase shift in longer antennas doesn't add any additional information. Since the amplitude is zero at that point, we already have all the phase information that we are going to get. We know at the zero point that the forward current and reflected current are 180 degrees out of phase. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
wrote in message oups.com... Yuri Blanarovich wrote: We are having problem with people admitting there could be difference in the current across loading coils, and here the "problems" is what is the error? So lets stick to the big problem and fuggettabout detours and nitpicking. Yuri, K3BU Yuri, Rather than playing like Cecil and making words for others, please post the dates and statements made by people who say current cannot be uneven at each end of a coil. Now it's "cannot be uneven?" Your own words: To which W8JI replied: "The idea current is high in only the start of a coil is not correct. Model an antenna with EZnec, and look at the load. Model a coil in any software, and look at current. Read any textbook, even beginner's textbooks, and see what they say. Measure a real antenna yourself! ....... You are like to call names, insult people, and argue rather than take the time to learn basic electronics. This is in any book, including the ARRL Handbook. If you look at HOW an inductor works, the current flowing in one terminal ALWAYS equals the current flowing out the other terminal. and..... Measuring the current into and out of the loading coil with a small thermocouple RF meter, I detect no difference This is in close agreement with the model. " " Show us where that is said with an exact in context quote, don't pull a Cecil and invent something that you expect us to blindly accept as the truth. It would help if we knew what you were talking about. 73 Tom You still don't know what are we talking about? Cecil is playing? Can you answer questions that he posted and I posted? 73 Yuri |
Current across the antenna loading coil - from scratch
Roy Lewallen wrote:
And in any case, the statement about EZNEC is incorrect. As I explained in a posting a short while ago, EZNEC has no awareness of nor does it make any use of traveling wave currents or voltages. It calculates only the total current from fundamental rules which don't involve traveling waves. For anyone who thinks EZNEC doesn't report traveling wave currents differently from standing wave currents, please download the following files. http://www.qsl.net/w5dxp/testx.EZ This is a *traveling wave file*. EZNEC reports the nearly linear phase of the current from 0 degrees at the source to 90 degrees at the load. The file comes with a zero load in the center of that 90 degree run. EZNEC reports the current's phase at 45 degrees at that zero load. http://www.qsl.net/w5dxp/testy.EZ Removing the resistive load from testx.EZ turns it into a *standing wave configuration*. EZNEC reports the phase of the current close to zero degrees all up and down the wire. The file comes with a zero load in the center of the same wire as above. EZNEC reports the current's phase very near zero degrees. The phase is near zero degrees all up and down wire 2. Contrary to what you have been told, EZNEC clearly reports the difference between the traveling wave configuration and the standing wave configuration. The traveling wave current phase can be used to measure the phase shift through the wire (or through a coil). The standing wave current phase cannot. To summarize: For the traveling wave configuration, the current magnitude is essentially constant all up and down the line while the phase shifts smoothly from zero degrees at the source to 90 degrees at the resistive load. For the standing wave configuration, the current magnitude follows the familiar cosine envelope from source at zero degrees to the end of the antenna at 90 degrees. The phase of the standing wave current is unchanging near zero degrees all up and down the wire. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
Ian White GM3SEK wrote:
In an Internet discussion, everybody has the right to attempt to switch the discussion away from the point. Everybody seems to understand how a coil works. Very few people understand how standing waves work. There's no point in discussing what people already understand. There's every point in discussing what people don't understand. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
Richard Clark wrote:
Any association between resonance, velocity of propagation, height, width, etc. and something like our 118.60° tall antenna needs a heap more explaining than resonance, velocity of propagation, height, width, etc. ______________ Now responding specifically to your request for a heap of explaining, you will find it in the George Brown paper I referenced earlier in this sub-thread. As that IRE paper from 1945 may be difficult to access now, you could refer to section 4-2 on the subject of cylindrical antennas in the "Antenna Engineering Handbook," 2nd edition (pub. 1984), by Johnson and Jasik -- from which this quote: "In practive the antenna is always fed by a transmission line. ... The effective terminal impedance of the line (often referred to as the antenna impedance) then depends not only on the length and diameter but also on the terminal condition." The text continues that for a MW monopole, the terminal condition consists of the characteristics of the ground plane. This section includes the plots of resistance and reactance for monopole radiators of various height to width ratios from George Brown's 1945 IRE paper. RF |
Current across the antenna loading coil - from scratch
Cecil Moore wrote:
The testx.EZ file has been renamed to: http://www.qsl.net/w5dxp/TravWave.EZ The testy.EZ file has been renamed to: http://www.qsl.net/w5dxp/StndWave.EZ The current reported by EZNEC for TravWave.EZ contains the term cos(kz+wt) It's a traveling wave current, clearly not the same as a standing wave current. The current reported by EZNEC for StndWave.EZ contains the terms cos(kz)*cos(wt) It's a standing wave current, clearly not the same as a traveling wave current. Current reported by EZNEC every 10% of wire #2 is presented in the following table. The currents are obviously very different. The phase of the traveling wave progresses from 0 to 90 deg in 90 deg of wire. The phase of the standing wave doesn't progress beyond 0.11 of of degree. % along current in current in wire #2 TravWave.EZ StndWave.EZ 0% 0.9998 at -0.99 deg 0.9996 at 0 deg 10% 0.9983 at -9.39 deg 0.9843 at -0.03 deg 20% 0.9983 at -18.23 deg 0.9454 at -0.05 deg 30% 0.9957 at -27.59 deg 0.8843 at -0.06 deg 40% 0.9949 at -35.96 deg 0.8023 at -0.08 deg 50% 0.9945 at -44.84 deg 0.7014 at -0.09 deg 60% 0.9945 at -54.2 deg 0.584 at -0.09 deg 70% 0.9949 at -62.58 deg 0.4528 at -0.1 deg 80% 0.9956 at -71.43 deg 0.311 at -0.11 deg 90% 0.9965 at -80.27 deg 0.1616 at -0.11 deg 100% 0.9976 at -89.14 deg 0.006073 at -0.11 deg Some say "current is current". EZNEC disagrees. When reflected waves are eliminated, EZNEC indeed does accurately report traveling wave current. EZNEC reports the current that is there, whether it is traveling wave current or standing wave current. I'm trying to learn how to graph the above current magnitude and phase in Mathcad but not having much luck. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
Cecil Moore wrote:
% along current in current in wire #2 TravWave.EZ StndWave.EZ 0% 0.9998 at -0.99 deg 0.9996 at 0 deg 10% 0.9983 at -9.39 deg 0.9843 at -0.03 deg 20% 0.9983 at -18.23 deg 0.9454 at -0.05 deg ^^^^^^ Sorry, a typo. Should be 0.9969 30% 0.9957 at -27.59 deg 0.8843 at -0.06 deg 40% 0.9949 at -35.96 deg 0.8023 at -0.08 deg 50% 0.9945 at -44.84 deg 0.7014 at -0.09 deg 60% 0.9945 at -54.2 deg 0.584 at -0.09 deg 70% 0.9949 at -62.58 deg 0.4528 at -0.1 deg 80% 0.9956 at -71.43 deg 0.311 at -0.11 deg 90% 0.9965 at -80.27 deg 0.1616 at -0.11 deg 100% 0.9976 at -89.14 deg 0.006073 at -0.11 deg -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
wrote in message oups.com... Yuri Blanarovich wrote: Your own words: To which W8JI replied: "The idea current is high in only the start of a coil is not correct. Model an antenna with EZnec, and look at the load. Model a coil in any software, and look at current. Read any textbook, even beginner's textbooks, and see what they say. Measure a real antenna yourself! Where is the entire context of that comment Yuri? You (and Cecil) have the habit of extracting things from context of a larger statement and exaggerating or putting a creative spin on what others say. If you were saying the current is high only in the first few turns of a coil that is not in a high order self-resonance, that is incorrect. Now you are putting words in my mouth. The question and argument WAS and IS about the current being (almost) equal (you claimed), or DIFFERENT (my et other's claim) at the ENDS of the loading coil. You stated "ALWAYS EQUAL" (Kirchoff, bla, bla...). As illustration and description of the effect I observed on the Hustler resonator was, that the heat developed from the bottom few turns. Like I am so stupid to claim that there is high current only in your few turns? Common' give me a break and fes up!! This is getting comical and pathetic. .. Anyone can look up the original posting about the development of the "story" at http://www.k3bu.us/loadingcoils.htm The whole dispute is summarized in Fig. 3 there, where it properly shows the shaded area representing reality - current and area at the whip after the loading coil vs. solid line representing misconception. (See degrees used there?) Anyone, even Richard can see that graphic representation of white area between the shaded area and triangular curve at the right, to see the the difference in efficiency ignored by the "same current" crowd - the white triangle is what you are missing! If you don't get it by now, then you have serious problem. Why don't you "gurus" repeat measurements, model it PROPERLY as solenoid or loading stub (or look at Cecil's examples) within the quarter wave resonant loaded antenna and tell me where and what IS WRONG on my web page. Step by step and arguments please. I am getting tired of this mental masturbation why it CAN'T BE when it IS. I tought that by now "same currentniks" would get it, but looks like too much resistance to admit being wrong. Well, looks like really need for comprehensive article to explain it, describe the experiments that anyone can replicate and set the record straight. If you choose not to believe it, that is your choice and you can live with it, who cares, really. Except that some people parade as experts, gurus, engineers, when they are not. They have odacity to attack others about misinformation, when they have same on their web pages. The even more sad thing is that apparently you influenced ON4UN to take the right information out of his latest edition of Low Band DXing book and replaced with your misinformation. It is all there in black and white, can't deny it, besides claiming being or having "JI Engineering" company, which you have no right to use that name or description, you ain't no engineer with degree. One last question Tom: How many electrical degrees has 60 ft tall tower (10" face) with circular (or hex, or whatever you choose) top hat of 20 ft diameter at 1.8 MHz? Can you answer Cecil's questions? Obviously NOT without admitting that you were and are wrong. No more "proofs" needed like potshots at Cecil's ex wife. I get better response from a brick wall when I hit it with hammer. I really have no more to say, the rest will be in the comprehensive article published for anyone to get the picture and decide for themseleves if this is important or valuable for them, or not. (I promise, I am peeved now :-) 73 Yuri Blanarovich, www.K3BU.us Rest is crap, twist and dance around the argument With couple more comments that I could not resist. :-) If you were saying the current is high in only the first few turns your statement was incorrect. Any dummy would know that it would be DISTRIBUTED along the coil, not in few turns that you picked or shorted out! Argument was ACROSS the coil, or at IT's ends. SAME (you) vs. DIFFERENT (me)!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Capish? If you were saying it had something to do with a cosign shape, your statement was not correct. Saying the current is NOT high in only the first few turns in a loading coil in a working system is NOT the same as saying the current does not vary or cannot vary. You are like to call names, insult people, and argue rather than take the time to learn basic electronics. This is in any book, including the ARRL Handbook. If you look at HOW an inductor works, the current flowing in one terminal ALWAYS equals the current flowing out the other terminal. That's true. The only thing that causes any differential is when the inductor has significant stray C to the outside world compared to the "through" impedance. Current can't just vanish. ITS THE STANDING WAVE CURRENT measurable with RF ammeters or current probes. How come it "vanishes" at the tip of quarter wave vertical, HUH???? Or you deny that too???? I think that was explained at the same time. As I recall the conversation, you were claiming current followed the same taper as the antenna area it replaced and claiming only the first few turns had high current. You claimed coil Q didn't matter because most of the current was high only in a few turns. CRAP! Make up some stories. I was trying to point out that idea, that the Q does not matter and the current is high only in the first few turns, is not correct by giving examples where we cannot measure the change with thermal couple meters. and..... Measuring the current into and out of the loading coil with a small thermocouple RF meter, I detect no difference This is in close agreement with the model. " " Measurements are at: http://www.w8ji.com/mobile_antenna_c...ts_at_w8ji.htm You still don't know what are we talking about? Cecil is playing? Can you answer questions that he posted and I posted? I've tried to answer every question Yuri, as have others. Does this help clear up what I was trying to say? WHERE? As I recall you were claiming Q did not matter because current was high only in the first few turns of a loading coil. Yea, riiiiight, I am so stuuuupid! I pointed out Q does not matter as people expect for a different reason. The real reason Q does not have the large effect on FS is ground losses in the system swamp out the effects of coil ESR. You said current difference was directly related to antenna area the loading coil replaced, that the loading coil had to have the same current slope as the area of antenna it replaced. If it replaced 80 degrees of antenna, it had to have the same current differential as that 80 degrees of antenna. Is that correct, or did I misunderstand you? I was giving counter-points to that claim. For example I posted this: http://www.w8ji.com/agreeing_measurements.htm Do you disagee with anything I say or Roy said when it is in context of the overall discussion?? YOU and Roy disagree with REALITY!!!!!!!!!!!! 73 Tom |
Current across the antenna loading coil - from scratch
Cecil Moore wrote:
Ian White GM3SEK wrote: In an Internet discussion, everybody has the right to attempt to switch the discussion away from the point. Everybody seems to understand how a coil works. Crucially, you don't. The main property of a "coil" is inductance, and at the most fundamental level you do not understand what inductance does. Very few people understand how standing waves work. Once again: crucially, you don't. You demand that ordinary electrical phenomena (like inductance and even current) change their properties or definitions in the presence of standing waves. You are doggedly trying to make those two misconceptions cancel each other out. Won't work. There's no point in discussing what people already understand. There's every point in discussing what people don't understand. I certainly agree with that... but we may differ about who we mean by "people" :-) -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
Current across the antenna loading coil - from scratch
Yuri Blanarovich wrote: If you were saying the current is high only in the first few turns of a coil that is not in a high order self-resonance, that is incorrect. Now you are putting words in my mouth. The question and argument WAS and IS about the current being (almost) equal (you claimed), or DIFFERENT (my et other's claim) at the ENDS of the loading coil. You stated "ALWAYS EQUAL" (Kirchoff, bla, bla...). OK, I agree the current CAN be different. Of course that has nothing to do with the amount of antenna the coil replaces, it is a function of the physical construction of the loading coil and how much capacitance the coil has from the coil to the outside world compared to the capacitance terminating the loading coil. As illustration and description of the effect I observed on the Hustler resonator was, that the heat developed from the bottom few turns. Like I am so stupid to claim that there is high current only in your few turns? Common' give me a break and fes up!! This is getting comical and pathetic. Well, I thought that was what you said. If you didn't say it, I have to take your word for it. |
Current across the antenna loading coil - from scratch
Awww, MAN,Cecil. I am sorry. I had no idea that you were putting up
with a newsreader that can't follow threads, and in addition you have such a severe short term memory loss that you can't follow what's been posted within the past couple hours. Bummer, man. Real bummer. I feel for you. It's a really bad combination. We should be able to help you out with the newsreader problem if you want. I'm not so sure about the memory loss thing, though. It might help if you didn't try to keep so many balls in the air all at once, but I don't know that for certain. I've patched together below (from the newsreader I use, which does keep track of all the branches of threads) what I wrote and what I was replying to in this particular sub-thread, so you can see it all in one place. If you'd like, I could do the same with the postings from other sub-threads here and from that other thread-that-wouldn't-die and email it to you, but that would be on a time-permitting basis. Cheers, Tom ------------------- ------------------- The above is in reply to: ------------------- Path: g2news1.google.com!news2.google.com!news3.google.c om!border1.nntp.dca.giganews.com!nntp.giganews.com !newscon06.news.prodigy.com!prodigy.net!newsmst01b .news.prodigy.com!prodigy.com!postmaster.news.prod igy.com!newssvr25.news.prodigy.net.POSTED!00eff025 !not-for-mail From: Cecil Moore User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.2) Gecko/20040804 Netscape/7.2 (ax) X-Accept-Language: en-us, en MIME-Version: 1.0 Newsgroups: rec.radio.amateur.antenna Subject: Current across the antenna loading coil - from scratch References: . com .com t .com In-Reply-To: .com Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Lines: 29 Message-ID: NNTP-Posting-Host: 64.149.30.33 X-Complaints-To: X-Trace: newssvr25.news.prodigy.net 1144183841 ST000 64.149.30.33 (Tue, 04 Apr 2006 16:50:41 EDT) NNTP-Posting-Date: Tue, 04 Apr 2006 16:50:41 EDT Organization: SBC http://yahoo.sbc.com X-UserInfo1: [[PA@SZG@@WCC^H]]RKB_UDAZZ\DPCPDLXUNNHDK@YUDUWYAKVUOPCW[ML\JXUCKVFDYZKBMSFX^OMSAFNTINTDDMVW[X\THOPXZRVOCJTUTPC\_JSBVX\KAOTBAJBVMZTYAKMNLDI_MFD SSOLXINH__FS^\WQGHGI^C@E[A_CF\AQLDQ\BTMPLDFNVUQ_VM Date: Tue, 04 Apr 2006 20:50:41 GMT K7ITM wrote: You really think so, Cecil?? I saw through it the first time you posted it. As an EZNEC and NEC2 user, I know that not only the current magnitude, but also its phase, is reported. I knew that what you posted about it was incorrect. I don't see Roy's comment as agreeing with you at all, but completely disagreeing. You said that it only gave amplitude information, when in fact it gives phase and amplitude. Again, no quote from me. I have no idea to what you are responding or even if you are responding to something I said today or last year. I didn't say EZNEC doesn't give phase information. I said there is no phase information in the phase information that EXNEC gives. What is it about Gene's posting that you don't understand? Regarding the cos(kz)*cos(wt) term in a standing wave: Gene Fuller, W4SZ wrote: In a standing wave antenna problem, such as the one you describe, there is no remaining phase information. Any specific phase characteristics of the traveling waves died out when the startup transients died out. Phase is gone. Kaput. Vanished. Cannot be recovered. Never to be seen again. The only "phase" remaining is the cos (kz) term, which is really an amplitude description, not a phase. -- 73, Cecil http://www.qsl.net/w5dxp ------------------------------- ------------------------------- which was in reply to my message: ------------------------------- Path: g2news1.google.com!postnews.google.com!e56g2000cwe .googlegroups.com!not-for-mail From: "K7ITM" Newsgroups: rec.radio.amateur.antenna Subject: Current across the antenna loading coil - from scratch Date: 4 Apr 2006 13:26:07 -0700 Organization: http://groups.google.com Lines: 7 Message-ID: .com References: . com .com t NNTP-Posting-Host: 192.25.142.225 Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" X-Trace: posting.google.com 1144182372 31795 127.0.0.1 (4 Apr 2006 20:26:12 GMT) X-Complaints-To: NNTP-Posting-Date: Tue, 4 Apr 2006 20:26:12 +0000 (UTC) In-Reply-To: User-Agent: G2/0.2 X-HTTP-UserAgent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.7.2) Gecko/20040804 Netscape/7.2 (ax),gzip(gfe),gzip(gfe) Complaints-To: Injection-Info: e56g2000cwe.googlegroups.com; posting-host=192.25.142.225; posting-account=phdUIAwAAABBVjeZzACGtATOLRtXatU- You really think so, Cecil?? I saw through it the first time you posted it. As an EZNEC and NEC2 user, I know that not only the current magnitude, but also its phase, is reported. I knew that what you posted about it was incorrect. I don't see Roy's comment as agreeing with you at all, but completely disagreeing. You said that it only gave amplitude information, when in fact it gives phase and amplitude. ------------------------------- ------------------------------- which was in reply to Cecil's message: ------------------------------- Path: g2news1.google.com!news2.google.com!news4.google.c om!news.glorb.com!newscon02.news.prodigy.com!prodi gy.net!newsmst01b.news.prodigy.com!prodigy.com!pos tmaster.news.prodigy.com!newssvr25.news.prodigy.ne t.POSTED!00eff025!not-for-mail From: Cecil Moore User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.2) Gecko/20040804 Netscape/7.2 (ax) X-Accept-Language: en-us, en MIME-Version: 1.0 Newsgroups: rec.radio.amateur.antenna Subject: Current across the antenna loading coil - from scratch References: . com .com t In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Lines: 15 Message-ID: NNTP-Posting-Host: 64.149.30.33 X-Complaints-To: X-Trace: newssvr25.news.prodigy.net 1144179596 ST000 64.149.30.33 (Tue, 04 Apr 2006 15:39:56 EDT) NNTP-Posting-Date: Tue, 04 Apr 2006 15:39:56 EDT Organization: SBC http://yahoo.sbc.com X-UserInfo1: OP\YG\GFEB^UCWDYIBHZOWP@YZOZ@GXOXJXNMRQIMASJETAANV W[AKWZE\]^XQWIGNE_[EBL@^_\^JOCQ^RSNVLGTFTKHTXHHP[NB\_C@\SD@EP_[KCXX__AGDDEKGFNB\ZOKLRNCY_CGG[RHT_UN@C_BSY\G__IJIX_PLSA[CCFAULEY\FL\VLGANTQQ]FN Date: Tue, 04 Apr 2006 19:39:56 GMT Roy Lewallen wrote: I see that Cecil's latest fetish is that EZNEC reports RMS values of voltage and current. Because we know that the voltages and currents are purely sinusoidal, the RMS value and phase angle (also reported by EZNEC) are adequate to define the time waveform. That is, when we know the RMS amplitude and the phase angle, we know the value of the waveform at every instant in time. No additional information is necessary. Since you agree with me, what's with the fetish remark? You seem to feel obliged to take an ad hominem pot shot every time you mention my name. I assure you, it is hurting your reputation more than it is hurting mine. -- 73, Cecil http://www.qsl.net/w5dxp ------------------------------- ------------------------------- By implication, this is also with respect to what Cecil wrote at the end of another subthread. The in-reply-to-s can be used to trace things back...: ------------------------------- Path: g2news1.google.com!news2.google.com!news3.google.c om!border1.nntp.dca.giganews.com!nntp.giganews.com !newscon06.news.prodigy.com!prodigy.net!newsmst01b .news.prodigy.com!prodigy.com!postmaster.news.prod igy.com!newssvr25.news.prodigy.net.POSTED!00eff025 !not-for-mail From: Cecil Moore User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.2) Gecko/20040804 Netscape/7.2 (ax) X-Accept-Language: en-us, en MIME-Version: 1.0 Newsgroups: rec.radio.amateur.antenna Subject: Current across the antenna loading coil - from scratch References: . com .com .com om t . com .com In-Reply-To: .com Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Lines: 30 Message-ID: NNTP-Posting-Host: 64.149.30.33 X-Complaints-To: X-Trace: newssvr25.news.prodigy.net 1144181906 ST000 64.149.30.33 (Tue, 04 Apr 2006 16:18:26 EDT) NNTP-Posting-Date: Tue, 04 Apr 2006 16:18:26 EDT Organization: SBC http://yahoo.sbc.com X-UserInfo1: OP\YG\GFEB^UCWDYIBHZOWP@YZOZ@GXOXJXNMRQIMASJETAANV W[AKWZE\]^XQWIGNE_[EBL@^_\^JOCQ^RSNVLGTFTKHTXHHP[NB\_C@\SD@EP_[KCXX__AGDDEKGFNB\ZOKLRNCY_CGG[RHT_UN@C_BSY\G__IJIX_PLSA[CCFAULEY\FL\VLGANTQQ]FN Date: Tue, 04 Apr 2006 20:18:26 GMT K7ITM wrote: I beg your pardon? Excuse me? I "trimmed out all the technical content and didn't quote anything you said"??? Yes, and you are doing it again. I'm quoting your entire posting and there is not one quote from me. As a matter of fact, I took exactly the numbers you gave us, ALL of them, and used them and ONLY them in my accounting. If THAT's "disembodied from reality," then I'd point out that it's YOUR numbers that are disembodied from reality. In fact, I didn't argue with YOUR numbers at all. I just took them at face value. You were the one that discarded what I carefully developed from them without out so much as an ounce of reasoning or explanation. After that I went on to FURTHER EXPLAIN why I had done what I did in the first place, and you dismissed that again without any technical explanation. It's all there for everyone to see, Cecil. If there's a quote from me in this posting, Tom, I am unable to find it. Go ahead, dig yourself deeper into it. Since you didn't quote anything I said, I have no idea what you are talking about. -- 73, Cecil http://www.qsl.net/w5dxp ------------------------------- ------------------------------- |
Current across the antenna loading coil - from scratch
Ian White GM3SEK wrote:
Cecil Moore wrote: Everybody seems to understand how a coil works. Crucially, you don't. The main property of a "coil" is inductance, and at the most fundamental level you do not understand what inductance does. Please stop the mind fornication, Ian. I understand how a coil works and I agree with you how a coil works in a lumped circuit or a traveling wave environment. It's obvious that our basic disagreement is NOT about coils but is, instead, about standing waves. If one doesn't understand standing waves, one cannot understand standing waves in empty space, in a wire, or in a coil. Take away the coil leaving nothing but wire. You and I still disagree regarding traveling waves Vs standing waves. Take away the wire and leave nothing but empty space containing standing waves of light. You and I still disagree regarding traveling waves Vs standing waves. Let's discuss our point of disagreement, not something that we agree upon. Very few people understand how standing waves work. Once again: crucially, you don't. You demand that ordinary electrical phenomena (like inductance and even current) change their properties or definitions in the presence of standing waves. I just posted some tabular current data from EZNEC. EZNEC says that current changes its properties in the presence of standing waves. It's there in black and white for all to see. Please explain how those two columns of data are identical. The traveling wave current magnitude is constant over the entire 90 degrees of wire. The standing wave current magnitude is a cosine function over that same 90 degrees of wire. The traveling wave current phase changes linearly over the entire 90 degrees of wire. The standing wave current phase is unchanging over that same 90 degrees if wire. That doesn't look the same to me. In fact, one could make an argument that traveling wave current and standing wave current are opposites of each other. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
wrote:
OK, I agree the current CAN be different. Therefore, you are admitting that you were wrong when you said: If you look at HOW an inductor works, the current flowing in one terminal ALWAYS equals the current flowing out the other terminal. At this point I'm not sure what you are saying. He's saying your original statement above was wrong. And now you admit it was wrong. Congratulations on that admission. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
K7ITM wrote:
Awww, MAN,Cecil. I am sorry. I had no idea that you were putting up with a newsreader that can't follow threads, and in addition you have such a severe short term memory loss that you can't follow what's been posted within the past couple hours. My newsreader is indeed unthreaded. I remember what was posted but sometimes not by who. We should be able to help you out with the newsreader problem if you want. I prefer my newsreader unthreaded. I read postings in the order in which they are received by my newsserver. Nothing else is ever downloaded. If the context of a posting is not quoted, I never see it. I've patched together below (from the newsreader I use, which does keep track of all the branches of threads) what I wrote and what I was replying to in this particular sub-thread, so you can see it all in one place. I still don't see any technical content in those postings. I do apologize if I have offended you but I still don't understand how. But that is water under the bridge by now. Sorry, the discussion has progressed beyond coils. Take a look at my other posting about what EZNEC says about traveling wave current Vs standing wave current and you will be up to date. Then you can use your lumped-circuit theory to explain the major differences in those two kinds of currents reported by EZNEC. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
K7ITM wrote:
From where I am, Cecil, it sounds a lot more like everyone is bored to tears with standing waves, since they are nothing more than the result of adding together a couple travelling waves, and everyone here understood them LONG ago. Everyone *thought* they understood them. The assertion that "current is current" proves that they didn't really understand them. cos(kz + wt) is simply not the same thing as cos(kz)*cos(wt) There is no trig idenity that will make them the same. Even W7EL's assertion about EZNEC not worrying about traveling wave current is wrong. When reflected current is eliminated in the traveling wave antenna design, EZNEC faithfully reports the traveling wave current proportional to cos(kx+wt). Please comment on the tabular data that I posted from EZNEC. And again, I apologize for offending you. As I've posted before, and as far as I know nobody's taken me up on it, it's quite enlightening to see an animation of the standing wave+travelling wave pattern that develops on a transmission line for various values of the ratio between the two travelling wave amplitudes. But once you've seen it, and likely even before, you know what you need, and (most of us) can move on I've posted this java graphic before. The standing wave current is obviously not the same as the traveling current. http://users.pandora.be/educypedia/e...stwaverefl.htm -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
On Wed, 5 Apr 2006 09:27:13 -0400, "Yuri Blanarovich"
wrote: Anyone, even Richard can see that graphic representation of white area between the shaded area and triangular curve at the right, to see the the difference in efficiency ignored by the "same current" crowd - the white triangle is what you are missing! Hi Yuri, I can also see that any metrics are entirely missing as to ACTUAL efficiency. You already admit you don't know and don't really care to go there when you dismiss this discussion: On Tue, 4 Apr 2006 16:47:05 -0400, "Yuri Blanarovich" wrote: So lets stick to the big problem and fuggettabout detours and nitpicking. This "big problem and nitpicking" is girly talk when they are giggling about Desperate Housewives. It is most obvious you enjoy the cat fight with Tom and don't give a hoot about a technical presentation. 73's Richard Clark, KB7QHC |
Current across the antenna loading coil - from scratch
I'm sorry, Cecil, but that Java applet is a poor cousin of what I had
in mind. It only tells part of the story. Please re-read my message carefully. Cheers, Tom Cecil Moore wrote, in Message-ID: : K7ITM wrote: From where I am, Cecil, it sounds a lot more like everyone is bored to tears with standing waves, since they are nothing more than the result of adding together a couple travelling waves, and everyone here understood them LONG ago. Everyone *thought* they understood them. The assertion that "current is current" proves that they didn't really understand them. cos(kz + wt) is simply not the same thing as cos(kz)*cos(wt) There is no trig idenity that will make them the same. Even W7EL's assertion about EZNEC not worrying about traveling wave current is wrong. When reflected current is eliminated in the traveling wave antenna design, EZNEC faithfully reports the traveling wave current proportional to cos(kx+wt). Please comment on the tabular data that I posted from EZNEC. And again, I apologize for offending you. As I've posted before, and as far as I know nobody's taken me up on it, it's quite enlightening to see an animation of the standing wave+travelling wave pattern that develops on a transmission line for various values of the ratio between the two travelling wave amplitudes. But once you've seen it, and likely even before, you know what you need, and (most of us) can move on I've posted this java graphic before. The standing wave current is obviously not the same as the traveling current. http://users.pandora.be/educypedia/e...stwaverefl.htm -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
On Wed, 5 Apr 2006 07:33:10 -0500, "Richard Fry"
wrote: The text continues that for a MW monopole, the terminal condition consists Problems here. 1. This was not a heap of explaining, only a pile; 2. this was not explaining at all, merely description; 3. this does not explain how a 118.60° tall antenna comes to be resonant through On Tue, 4 Apr 2006 12:11:20 -0500, "Richard Fry" wrote: The effective electrical length of a MW monople radiator determines its resonant frequencies, and that must include the velocity of propagation along the structure -- which is a function of the height AND width of the radiator (mainly), and the operating frequency. Using your reference "Antenna Engineering Handbook," 2nd edition (pub. 1984), by Johnson and Jasik and having me carry your water of explaining, we find in figure 4-4 the correlation between resonance (the absence of reactance), length, and diameter gives us a necessarily wide antenna of 13.9 meters I cannot recall ever seeing any tower with a 45 foot diameter in a commercial setting. However, that is not to say it doesn't exist, merely that the odds for it are ridiculously astronomical. If we browse the FCC database for other antennas to see how well your reference "explains" how your quote above provides a resonance for them, then we come across rather more astronomical odds being fulfilled. WFLF 75.00° tall 540 kHz requires a tower diameter of 364 feet =whew!= KNOE 63.00° tall 540 kHz Let's just say that is so far off the charts it ceases to be astronomic and becomes galactic in improbability. Basically this reveals the breakdown in hyperbole's capacity to describe the metaphor of improbability - especially in the face of these examples that follow: WGOP (POCOMOKE CITY) 63.00° tall 540 kHz WWCS 63.50° tall 540 kHz WYNN 65.50° tall 540 kHz KDFT 59.30° tall 540 kHz WXNH 56.30° tall 540 kHz WLIE 62.30° tall 540 kHz There's no point going further as this hardly exhausts one frequency assignment, much less the AM band. The long and the short of it stands with my original statement: Any association between resonance, velocity of propagation, height, width, etc. and something like our 118.60° tall antenna needs a heap more explaining than resonance, velocity of propagation, height, width, etc. - but such explaining is a specialty occupation here in this group. Expanding slightly, it is absurd to attach a 90° tall claim to an antenna simply because it has been resonated through adaptive measures. Unfortunatley, being absurd is also a specialty occupation here in this group. 73's Richard Clark, KB7QHC |
Current across the antenna loading coil - from scratch
On Wed, 05 Apr 2006 12:56:07 GMT, Cecil Moore
wrote: Sorry, a typo. Should be 0.9969 Let's see, you responded to Roy twice, then responded to yourself, and then responded to yourself again - DAMN, you are really trying hard to convince yourself. In your pursuit of a solitary pleasure, I can't tell which perspective has the worst prospect: the teacher's, or the student's. |
Current across the antenna loading coil - from scratch
"Richard Clark" wrote Hi Yuri, I can also see that any metrics are entirely missing as to ACTUAL efficiency. You already admit you don't know and don't really care to go there when you dismiss this discussion: But graphic representation gives rough idea to realize that it is not unimportant or worthy ignoring. If you wanna get precise metrics, stick the two versions of coil definition in the EZNEC, generate the curves and compare areas under the curve from the top of the coil to the tip. Then tell us that is negligible and was not worth of this exercise. I will get to it soon too. Yuri, K3BU |
Current across the antenna loading coil - from scratch
"Richard Clark"
3. this does not explain how a 118.60° tall antenna comes to be resonant through On Tue, 4 Apr 2006 12:11:20 -0500, "Richard Fry" wrote: The effective electrical length of a MW monople radiator determines its resonant frequencies, and that must include the velocity of propagation along the structure -- which is a function of the height AND width of the radiator (mainly), and the operating frequency. ______________ I have not stated that an unloaded broadcast monopole of any physical height should be made self-resonant, or even needs to be, for efficient radiation. Very few broadcast monopoles are. The ones that aren't are matched to resonance and the transmission line Zo by a network at the antenna feedpoint, as I also stated. What I wrote is that a radiator of "90 electrical degrees" when shown in the FCC database is NOT self-resonant, and referred to the experimental data from George Brown, and the work of Johnson & Jasik to confirm what I wrote. Kraus, 3rd edition, Ch 14 has the mathematical analysis to support this, also. NEC shows this effect, as well. The rest of the examples in your post are based on your invalid assumption, for which my response is given above. RF |
Current across the antenna loading coil - from scratch
Cecil Moore wrote:
Ian White GM3SEK wrote: Cecil Moore wrote: Everybody seems to understand how a coil works. Crucially, you don't. The main property of a "coil" is inductance, and at the most fundamental level you do not understand what inductance does. Please stop the mind fornication, Ian. I am simply telling you straight. If you find the implications disturbing beyond the import of my actual words, that is beyond my control. I understand how a coil works and I agree with you how a coil works in a lumped circuit or a traveling wave environment. It's obvious that our basic disagreement is NOT about coils but is, instead, about standing waves. Our basic disagreements are about coils *and* current *and* their behaviour when standing waves are present. There's no point in switching the discussion to cover only part of those topics. -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
Current across the antenna loading coil - from scratch
Ian White GM3SEK wrote:
I am simply telling you straight. If you find the implications disturbing beyond the import of my actual words, that is beyond my control. You are trying to tell me what I think when you have no clue as to what I am thinking. Excuse my French, but that is called mind-****ing, Ian. Please cease and desist from that practice. The only ethical and honest thing you can say about my postings is, "it seems to me that you are saying or thinking such and such ..." Our basic disagreements are about coils *and* current *and* their behaviour when standing waves are present. There's no point in switching the discussion to cover only part of those topics. Not switching the discussion to the only salient point of disagreement will obfuscate the discussion. If that's what you want to do, then your reasons for doing so are quite obvious, and readers are likely to assume that you are not interested in technical facts at all but more interested in preserving your omniscient guru status through obfuscation. So the real question is: Why have you avoided responding to my tabular current posting based on EZNEC's take on traveling wave current Vs standing wave current? Some may assume from that lack of response that you are afraid to address the technical facts as are W8JI and W7EL. If you guys are so right, why are you afraid of discussint the technical issues that I have posted? -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
Cecil Moore wrote:
Ian White GM3SEK wrote: I am simply telling you straight. If you find the implications disturbing beyond the import of my actual words, that is beyond my control. You are trying to tell me what I think when you have no clue as to what I am thinking. Excuse my French, but that is called mind-****ing, Ian. Please cease and desist from that practice. The only ethical and honest thing you can say about my postings is, "it seems to me that you are saying or thinking such and such ..." I have no interest whatever in the workings of your mind. My only interest is in what you say to the outside world. Based entirely on what you yourself have written, I have told you that you don't understand something. If you cannot handle that, and regard it as an attempt to invade your mind, then this whole thing has gone way too far. -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
Current across the antenna loading coil - from scratch
On Wed, 5 Apr 2006 13:51:11 -0400, "Yuri Blanarovich"
wrote: But graphic representation gives rough idea to realize that it is not unimportant or worthy ignoring. Hi Yuri, But it gives nothing of that impression at all. If it were important, then you could give me solid numbers instead of an art review. If you wanna get precise metrics, stick the two versions of coil definition in the EZNEC, generate the curves and compare areas under the curve from the top of the coil to the tip. Then tell us that is negligible and was not worth of this exercise. Yuri, I did that two years ago. You have yet to disagree with the pitiful difference and the best chance of you doing it yourself is: I will get to it soon too. I heard that two years ago too. You don't give any impression that the topic at hand is nearly as important to you as duking it out with Tom. But if after two years of swinging and you still haven't connected a solid KO, don't expect us to hand you a TKO (because your Technical part is a marshmallow punch). 73's Richard Clark, KB7QHC |
Current across the antenna loading coil - from scratch
On Wed, 5 Apr 2006 15:07:53 -0500, "Richard Fry"
wrote: The rest of the examples in your post are based on your invalid assumption, for which my response is given above. Sounds like you have a problem following context. The Xerox school of churning out references and loose associations is already chaired by Cecil. 73's Richard Clark, KB7QHC |
Current across the antenna loading coil - from scratch
"Richard Clark"wrote
Sounds like you have a problem following context. ___________ No, from your posts IMO it is YOU who has a problem with your reading comprehension, and/or possibly your professional integrity. I posted "The effective electrical length of a MW monopole radiator determines its resonant frequencies, and that must include the velocity of propagation along the structure -- which is a function of the height AND width of the radiator (mainly), and the operating frequency." I have also posted several references in the literature which support this in technical detail. You then posted "3. this does not explain how a 118.60° tall antenna comes to be resonant ," and several ridiculous examples of broadcast tower widths of 364 feet and more that you falsely attribute as flowing from my statements. Contrary to your recent post, I have never written anything that remotely implied that your 118.60 degree radiator, or a broadcast radiator of any other length can/should be made self-resonant by the use of an impractical ratio of width to length. I have posted several times that (conventional) broadcast radiators that are not self-resonant are brought to resonance at the feedpoint by the use of a matching network there. If you can find ANYTHING in my posts on this subject to support your statements, please quote them to the NG. Otherwise I suggest you let this thread close, and (hopefully), learn from it. RF |
Current across the antenna loading coil - from scratch
I'm not at all sure what all the hoop-lah following Richard Fry's
posting reproduced below is all about. What Richard wrote is accurate, as he says confirmed by NEC simulation, and also from the King-Middleton second-order theory of linear antennas. From the date, it sounds like Brown's paper was a confirmation of the theory, actually. An antenna resonant at 95% of a freespace quarter wave, above perfect ground, would be about 150 times as long as its diameter--a 75 meter tower about half a meter effective diameter. NEC gives slightly different numbers, but perhaps more interesting is that even for VERY thin wires, the resonant length is noticably shorter than a freespace quarter wave. A wire a millionth as thick as it is long still shows resonance more than a percent shorter than the freespace wavelength. It's an interesting observation, but I thought everyone (with a serious interest in antennas) would know about it. The effect at full-wave dipole resonance/half-wave above a ground plane is considerably more pronounced, over ten percent for a moderately thick antenna. Cheers, Tom Richard Fry wrote in Message-ID: : "Richard Harrison" wrote: It is the convention to describe AM broadcast towers in electrical degrees. Harold Ennes reprints an RCA resistance chart for heights between 50 and 200 degrees in "AM-FM Broadcast Maintenance". Formula given is: Height in electrical degrees = Height in feet X frequency in kc X 1.016 X 10 to the minus 6 power. _______________ If electrical length is defined as the physical condition where feedpoint reactance is zero (e.g., resonance), then the true electrical length of an AM broadcast radiator on a given frequency is a function of the physical length AND physical width of that radiator. This was proven experimentally, and documented by George Brown of RCA Labs in his paper "Experimentally Determined Impedance Characteristics of Cylindrical Antennas" published in the Proceedings of the I.R.E. in April, 1945. It also has been proven in thousands of independent measurements of AM broadcast radiators ever since. The curves in Figure 3 of Brown's paper show the feedpoint reactance terms of the base impedance of an unloaded monopole of various lengths and widths, working against a nearly perfect ground plane. Those values cross the zero reactance axis at physical heights ranging from about 80 degrees (for the widest radiator) to about 86 degrees for the most narrow. Brown calculated height in degrees as (Physical Height in feet x Frequency in kHz ) / 2725 . Brown's equation, the one in the Harold Ennes quote above, and the one that the FCC uses in their published data all define only the relationship of the physical length of the radiator to its free-space wavelength in degrees at that frequency. But clearly these lengths in degrees do not define the self-resonant length of that radiator. The self-resonant length, invariably, will be shorter by several percent. This fact is easily confirmed by simple NEC models, for those who want to probe into George Brown's data. Tables relating a single value of base impedance as typical for towers of various electrical heights (only) must be read with an understanding of the above realities. For example, Ennes' list shows a tower of 90 electrical degrees to have zero reactance. But Brown's 1945 paper and a great amount of later field experience shows that this is incorrect, for the conventional use of this term. RF |
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