|
I find it amazing that the only argument you guys can come up with is an ad hominem attack. That's usually the last resort of someone who has lost the argument. If I am so technically incorrect, is one iota of technical proof too much to ask? It is, of course, if this is a good- old-boys EM religion discussion rather than a technical discussion. -- 73, Cecil http://www.qsl.net/w5dxp Cecil, I admire your patience and civility, I will try to learn that. In the mean time, it is almost amusing, if not sad, to observe some educated idiots :-) Yuri, K3BU.us |
Gene Fuller wrote:
I was going to drop this discussion, but I will respond to your request to share physics knowledge. Thanks, Gene, Please be patient with me. 1) I will repeat. E-fields, H-fields, voltages, and currents are all related through some very profound equations. However, shout THEY ARE NOT INTERCHANGEABLE. /shout Is the H-field around a wire proportional to the RF current in the wire? Is the E-field around a wire proportional to the RF voltage between the wires? Is the ratio of E-field to H-field fixed by Z0? Do I^2*R losses affect the E-field and H-field by equal amounts? This is not just a matter of semantics. These entities have different physical meanings, different units, and different dimensionalities. Of course that's true. However, they are not unrelated. 2) I offered a physics-based explanation for your proposed "current drop" in the 440 MHz RG-58 example a few days ago. Did you not read that message before responding to it? Yes, and I have been thinking about an example that would better illustrate what I was asking. A 1000 wavelength dipole located in outer space would have less current at the ends than at the source. Since there is no other path for current, what is the explanation for the decrease in the current at the ends? 3) What is not correct is the assertion that the coil exhibits a phase shift consistent with, for example, 20 feet of wire used to make the coil. Because nobody has made that assertion since the original eHam article, it appears to be a straw man. The coil occupies whatever number of degrees that it occupies and it does NOT occupy zero degrees. For instance, using a particular EZNEC segment model of a coil, the current at the bottom is 1.0 amp and the current at the top is 0.5 amp. Assuming the cosine distribution of standing-wave current is accurate, the coil occupies about 60 degrees. The whip would occupy about 30 degrees, the rest of the 1/4WL. Nobody has attempted to explain how one can obtain 90 degrees of a 1/4WL antenna on 4 MHz using a ten foot (15 degree) whip. That is one hell of a velocity factor. If the bottom-loading coil really occupies zero degrees, then the ten foot whip would be forced to occupy 90 degrees. That is so impossible as to be laughable. The notion that a coil replaces some sizable portion of the total phase shift in an antenna has been shown to be incorrect. Experiments reported by Roy and Tom R. convincingly demonstrate the phase shift behavior of coils. The total current undergoes virtually no phase shift since it is a standing wave. That's in the textbooks and nobody is arguing that point so it's just another straw man. It's the forward current and reflected current that is undergoing a phase shift through the coil just like they do on a wire standing- wave antenna. Nobody has measured those two current components so the jury is still out on that subject. There is no argument about the phase of the total current that Roy and Tom measured. Please, there are enough arguments already without having to introduce straw men. If you will look at my phasor diagrams of forward and reflected currents at: http://www.qsl.net/w5dxp/current.htm you will see that the phase of the total current is exactly the same in both cases. That's the phase that Roy measured. Since it is a standing wave current, the phase of the standing-wave current is almost constant. It is the magnitude of the standing-wave current that changes and it changes as a cosine function of electrical length in degrees. The coil has an electrical length in degrees. That's what causes the current to be different at the bottom and at the top in a 1/4WL antenna. Assuming the phase shift from the feedpoint current to the tip of the antenna is 90 degrees, if an accurate measurement of the current at the top and bottom of a bottom-loaded antenna coil is made, the number of degrees occupied by the coil can be calculated from arccos(Itop/Ibottom) just as it can be calculated between two points on a wire. This assumes that Ibottom is an Imax point on the standing wave. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Cecil,
1) Only the total current matters. I have never found a detailed treatment of antennas that was based on anything other than the total current (or total current density) at each point on the antenna. Have you? Current components may be useful for discovering the total current or for handwaving explanations, but they have no further role in antenna analysis. 2) Where did this 90 degree phase shift requirement come from? There is virtually no phase shift in the current of a half-wave dipole (or quarter-wave monopole) from feedpoint to tip. I am looking at figure 9.6 on page 370 in Kraus "Antennas" (2nd Ed.), and it shows perhaps a few degrees phase variation over the entire length of the dipole antenna. This figure is located in the chapter on the Moment Method for calculating cylindrical antennas, in case you do not have the second edition. I suspect you may be confusing the argument (AKA, the phase) of the cosine function presumed to describe the behavior of the current amplitude. However, current amplitude and current phase are not at all the same thing. Have you been seduced by your math models? 73, Gene W4SZ Cecil Moore wrote: [snip] Because nobody has made that assertion since the original eHam article, it appears to be a straw man. The coil occupies whatever number of degrees that it occupies and it does NOT occupy zero degrees. For instance, using a particular EZNEC segment model of a coil, the current at the bottom is 1.0 amp and the current at the top is 0.5 amp. Assuming the cosine distribution of standing-wave current is accurate, the coil occupies about 60 degrees. The whip would occupy about 30 degrees, the rest of the 1/4WL. Nobody has attempted to explain how one can obtain 90 degrees of a 1/4WL antenna on 4 MHz using a ten foot (15 degree) whip. That is one hell of a velocity factor. If the bottom-loading coil really occupies zero degrees, then the ten foot whip would be forced to occupy 90 degrees. That is so impossible as to be laughable. The notion that a coil replaces some sizable portion of the total phase shift in an antenna has been shown to be incorrect. Experiments reported by Roy and Tom R. convincingly demonstrate the phase shift behavior of coils. The total current undergoes virtually no phase shift since it is a standing wave. That's in the textbooks and nobody is arguing that point so it's just another straw man. It's the forward current and reflected current that is undergoing a phase shift through the coil just like they do on a wire standing- wave antenna. Nobody has measured those two current components so the jury is still out on that subject. There is no argument about the phase of the total current that Roy and Tom measured. Please, there are enough arguments already without having to introduce straw men. If you will look at my phasor diagrams of forward and reflected currents at: http://www.qsl.net/w5dxp/current.htm you will see that the phase of the total current is exactly the same in both cases. That's the phase that Roy measured. Since it is a standing wave current, the phase of the standing-wave current is almost constant. It is the magnitude of the standing-wave current that changes and it changes as a cosine function of electrical length in degrees. The coil has an electrical length in degrees. That's what causes the current to be different at the bottom and at the top in a 1/4WL antenna. Assuming the phase shift from the feedpoint current to the tip of the antenna is 90 degrees, if an accurate measurement of the current at the top and bottom of a bottom-loaded antenna coil is made, the number of degrees occupied by the coil can be calculated from arccos(Itop/Ibottom) just as it can be calculated between two points on a wire. This assumes that Ibottom is an Imax point on the standing wave. |
Gene Fuller wrote:
1) Only the total current matters. I have never found a detailed treatment of antennas that was based on anything other than the total current (or total current density) at each point on the antenna. Have you? Check out my tag line, Gene. Balanis says we can use the component currents If and Ib to analyze a standing-wave antenna. Kraus says essentially the same thing when he says: "A sinusoidal current distribution may be regarded as the standing wave produced by two uniform (unattenuated) traveling waves of equal amplitude moving in opposite directions along an antenna." This was in regards to the "Fields of a thin linear antenna with a uniform traveling wave." Just because there is no "detailed treatment" doesn't mean that it should be forbidden to discuss. We are out on the edge of what has been detailed (so far) so don't be afraid to think outside of the box. The opposite phase shift between If and Ib is the cause of the decrease in coil current in a typical mobile antenna. It happens even if there is zero loss in the coil and zero radiation from the coil. It also happens in a lossless transmission line. There is a decrease in standing wave current on each side of a current maximum point even when the transmission line is lossless. The same thing applies to a lossless coil with dimensions larger than a point. Current components may be useful for discovering the total current or for handwaving explanations, but they have no further role in antenna analysis. Check my tag line again, Gene. They are absolutely useful for transmission line analysis and are therefore useful for standing-wave antenna analysis. 2) Where did this 90 degree phase shift requirement come from? There is virtually no phase shift in the current of a half-wave dipole (or quarter-wave monopole) from feedpoint to tip. Yes, you are talking about the standing-wave current which is the superposition of the forward and reflected currents. A 1/4WL wire is 90 degrees of a traveling-wave antenna. The forward current rotates by 90 degrees and the reflected current rotates by 90 degrees. I am looking at figure 9.6 on page 370 in Kraus "Antennas" (2nd Ed.), and it shows perhaps a few degrees phase variation over the entire length of the dipole antenna. Yes, that is true for the superposed forward and reflected currents and is shown to be true by my phasor diagrams on my web page. The forward current is a traveling wave. The reflected current is a traveling wave. I'm sure you are familiar with the change in phase undergone by traveling waves in perfectly matched systems. Apply that knowledge to the separate forward and reflected current traveling waves and you will understand the magnitude variation in If+Ib caused by their respective phase shifts in the opposite direction even if their magnitudes remain constant. I suspect you may be confusing the argument (AKA, the phase) of the cosine function presumed to describe the behavior of the current amplitude. However, current amplitude and current phase are not at all the same thing. Nope, I fully agree that the superposed net current has almost zero phase shift because it is a *standing wave*. Traveling waves, OTOH, experience phase shifts when traveling along a wire. The forward current and reflected current on a standing-wave antenna are *traveling waves*. This is an onion-type problem, Gene. Please peal back the net current layer and look at the component currents underneath even if you feel presently that it will be a waste of time. Incidentally, I bounced most of this stuff off of Dr. Balanis when I was working with him on a joint Intel/ASU project. He agreed so far (1995) and my extensions since 1995 are logical. If you will take it step-by-step, I think you will agree. If you find any error at all on my part, you will, no doubt, call my attention to it and I will learn something. -- 73, Cecil http://www.qsl.net/w5dxp "The current and voltage distributions on open-ended wire antennas are similar to the standing wave patterns on open-ended transmission lines ... Standing wave antennas, such as the dipole, can be analyzed as traveling wave antennas with waves propagating in opposite directions (forward and backward) and represented by traveling wave currents If and Ib ..." _Antenna_Theory_, Balanis, Second Edition, Chapter 10, page 488 & 489 ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Cecil,
Thanks. You just validated my point. Kraus absolutely does not use component currents for any serious analysis; he uses only total current. Likewise, it appears that Balanis is merely waving his hands as well. The quote you provided comes from Chapter 10, on traveling wave antennas, not from a chapter on simple dipole antennas. Does he actually load these components into equations and carry out the analysis in detail? Subcomponents of the current may be useful for handwaving explanations, but they are not superior to the standard net current model. Any modeling results must agree with the standard model (widely used for more than 100 years) or else the simple handwaving model is likely to be bogus. Soooo, we are back to the beginning. There is minimal current phase shift in a dipole or monopole antenna, certainly nothing like the the 30 to 60 degree "replacement" phase shift you have been claiming. There is no mysterious "current drop". Any reduction in measured (or modeled) current can (and must) be accounted by shunt currents. What's left? Bye, Gene W4SZ Cecil Moore wrote: Check out my tag line, Gene. Balanis says we can use the component currents If and Ib to analyze a standing-wave antenna. Kraus says essentially the same thing when he says: "A sinusoidal current distribution may be regarded as the standing wave produced by two uniform (unattenuated) traveling waves of equal amplitude moving in opposite directions along an antenna." This was in regards to the "Fields of a thin linear antenna with a uniform traveling wave." |
Gene Fuller wrote:
Thanks. You just validated my point. Kraus absolutely does not use component currents for any serious analysis; he uses only total current. Let me get this straight. Just because Kraus didn't use component currents for any serious analysis prohibits future thinkers from doing so? Do you really believe that anything Kraus didn't choose to include in his book should not be considered by human beings like you and me? (I don't recall him saying anything about sex.) :-) If you consider Kraus' book to be an Antenna Bible, then you are guilty of bringing metaphysics into physics. Likewise, it appears that Balanis is merely waving his hands as well. The quote you provided comes from Chapter 10, on traveling wave antennas, not from a chapter on simple dipole antennas. "Handwaving - anything that disagrees with your present EM religion" Does that prohibit you from considering the component currents? If so, what are you afraid that you will discover? You are perfectly free to put on the blinders, but to what purpose? Subcomponents of the current may be useful for handwaving explanations, but they are not superior to the standard net current model. Is the "standard net current model" so perfect that it will never be modified? Please think outside of the box on this one, Gene. You are essentially saying that all the human knowledge that has been accumulated on this subject is all that will ever be discovered. That reminds me of the patent clerk who, around 1900, declared that the patent office should be closed because all possible discoveries had already been made. Any modeling results must agree with the standard model (widely used for more than 100 years) or else the simple handwaving model is likely to be bogus. Can you prove that the "standard model" is perfect? If not, is there a chance that it is not perfect? Are you opposed to discovering imperfections in the "standard model"? Do you have the cahones to defend the standard model in a rational technical discussion? Soooo, we are back to the beginning. No, we are back to your EM metaphysics. I am begging you, Gene, please, please, allow yourself to think outside of the box. What do you have to lose except your religious-like beliefs? If your beliefs are correct, it should be relatively easy to prove me wrong. If your beliefs are incorrect, don't you want to change them? What, exactly, are you afraid of? The mere fact that you resort to an argumentum ad verecundiam (diversionary appeal to authority) argument tells me that you are afraid to consider anything new. So are you going to sandbag behind an omniscience flag, or are you going to engage in a rational technical discussion where the outcome is unknown? I am not trying to be difficult. In a one-on-one discussion, I will either be proven right or wrong. I'm not afraid of that - are you? -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
What's left? Bye, Gene W4SZ Take the RF ammeters, stick them at ends of coil and SEE wasaaaap! Bye, bye! Yuri, K3BU.us |
Gene Fuller wrote:
Kraus absolutely does not use component currents for any serious analysis; he uses only total current. Likewise, it appears that Balanis is merely waving his hands as well. The quote you provided comes from Chapter 10, on traveling wave antennas, not from a chapter on simple dipole antennas. Does he actually load these components into equations and carry out the analysis in detail? Subcomponents of the current may be useful for handwaving explanations, but they are not superior to the standard net current model. True. Although it's worth noting that the traveling waves, or subcomponenets as you call them, are actually the source of radiation. The fields generated by forward and reverse waves of course superpose to produce the net field. Obviously in practice it's considerably simpler to just superpose the currents in order to obtain the net field, but the result should be the same either way. Any modeling results must agree with the standard model (widely used for more than 100 years) or else the simple handwaving model is likely to be bogus. Soooo, we are back to the beginning. There is minimal current phase shift in a dipole or monopole antenna, certainly nothing like the the 30 to 60 degree "replacement" phase shift you have been claiming. There is no mysterious "current drop". Any reduction in measured (or modeled) current can (and must) be accounted by shunt currents. What's left? I have a question. If a loading coil only makes a physically short antenna look like it's an electrical quarter wavelength reactively, why does its position along the radiator make such an apparent difference in performance? 73, Jim AC6XG |
"Jim Kelley" wrote in message ... deletia.... I have a question. If a loading coil only makes a physically short antenna look like it's an electrical quarter wavelength reactively, why does its position along the radiator make such an apparent difference in performance? 73, Jim AC6XG My first reaction is to point out that this was (is?) a question on the Extra exam. Now how can I explain qualitatively why this is? Consider an end-fed wire antenna. An electromagnetic wave goes through the conduction electrons down to the end and reflects back. At 1/4 wavelength, the reflected wave is exactly in phase with the source so the load looks minimal and resistive, loss plus radiation. As the antenna gets shorter the radiation resistance gets lower and the reflected wave gets back to the feed point sooner (becomes capacitive). We need to add inductance to slow down the wave so it gets back in phase. We cannot, alas, raise the radiation resistance; this is a short antenna. If I place the inductor at the feed point all the current must flow through it, maximizing loss. If I place it at the top little current flows through it, minimizing effectiveness. If I distribute it the antenna's resonance is broader, but at what cost? Lower Q. The signal strength is less. So I make the coil as short as I can, put it in the middle and it's juuust right. 73, H. NQ5H |
If I place the
inductor at the feed point all the current must flow through it, maximizing loss. If I place it at the top little current flows through it, minimizing effectiveness. If I distribute it the antenna's resonance is broader, but at what cost? Lower Q. The signal strength is less. So I make the coil as short as I can, put it in the middle and it's juuust right. 73, H. NQ5H Simple rule, as mentioned in ON4UN book, the efficiency of the antenna is proportional to the area under the current curve. When you model the antenna and view the current distribution and compare various cases with coil positioned at bottom, middle, top, it is obvious why. It also shows why it is important to understand the role of the loading coil and its effect on the current distribution along the radiator. This effect gets magnified when using loaded elements in parasitic beam designs. If you use "zero" size inductance in modeling, the results are "too good" and correlation with reality is way off. That's what is all about. Yuri, K3BU.us |
H. Adam Stevens, NQ5H wrote:
We need to add inductance to slow down the wave so it gets back in phase. Exactly. The coil provides a delay and a phase shift. A series stub will accomplish the same thing. In the middle of an electrical 1/4WL antenna, any delay through the coil ensures unequal net current at the bottom and top of the coil even if the coil is lossless and non-radiating. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Jim Kelley wrote:
It seems that the phase shift you described earlier would have to cause a change in the standing wave pattern along the radiator. It does and that is why it is so difficult to write an equation for it. There are reflections in both directions at the top and bottom of the coil in addition to the 100% reflection at the tip of the antenna. My solution is to get Reg to write a new program. :-) If the loading coil was at the feedpoint, then the maximum current would appear only at the feedpoint. I hesitate to introduce secondary effects before most have understood the primary effects, but that is not a true statement. Some percentage of what the other side is saying is true. However, the other side considers those effects to be supreme when they are only secondary - but they are NOT negligible secondary effects. The maximum current in the base-loaded system does not appear at the feedpoint. The maximum current in a base-loaded system appears inside the coil and that current is of greater magnitude than the feedpoint current. I'm sorry to muddy the waters even farther with that tidbit. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
"Jim Kelley" wrote in message ... H. Adam Stevens, NQ5H wrote: "Jim Kelley" wrote in message ... deletia.... I have a question. If a loading coil only makes a physically short antenna look like it's an electrical quarter wavelength reactively, why does its position along the radiator make such an apparent difference in performance? 73, Jim AC6XG My first reaction is to point out that this was (is?) a question on the Extra exam. I think you may be right. Now how can I explain qualitatively why this is? Start with the answer to the exam question? :-) Consider an end-fed wire antenna. An electromagnetic wave goes through the conduction electrons down to the end and reflects back. At 1/4 wavelength, the reflected wave is exactly in phase with the source so the load looks minimal and resistive, loss plus radiation. As the antenna gets shorter the radiation resistance gets lower and the reflected wave gets back to the feed point sooner (becomes capacitive). We need to add inductance to slow down the wave so it gets back in phase. Is that the controversial phase shift? We cannot, alas, raise the radiation resistance; this is a short antenna. If I place the inductor at the feed point all the current must flow through it, maximizing loss. If I place it at the top little current flows through it, minimizing effectiveness. If I distribute it the antenna's resonance is broader, but at what cost? Lower Q. The signal strength is less. So I make the coil as short as I can, put it in the middle and it's juuust right. 73, H. NQ5H Sounds like you're describing a sort of 'current drop'. Is I^2R loss entirely responsible for this drop? It seems that the phase shift you described earlier would have to cause a change in the standing wave pattern along the radiator. If the loading coil was at the feedpoint, then the maximum current would appear only at the feedpoint. Above the coil, the currents would be out of phase, as you described, because of the shortened radiator, and the maximum available current would not flow along any point on the radiator. Moving the coil higher would allow maximum current to flow along at least the lower portion of the radiator. Loss is certainly a factor, but I can't see how it is the entire explanation for the rather pronounced effect. Hence my question. 73, Jim AC6XG Hi Jim Clearly an entire explanation would require a rigorous solution to Maxwell's equations, but you state it better than I did. The current below the loading coil is as if the antenna were full length, max power radiated; the voltage above the loading coil is as if the antenna were full length. And you're right, moving the coil away from the current max (feed point) reduces I^2R losses in the coil. Are there E^2/R losses in the coil if we mount it at the top? Looks like if we make the boundary conditions at the ends of the antenna as if it were full-length it works best. Remember the boundary conditions; the current is max at the feedpoint and zero at the end (can't go anywhere). The empirical fact is a lumped L in the center of the antenna works best and one can "sort of" intuitively see why placing the coil at either end has problems. Hence I use a 4 foot screwdriver and a 4 foot whip. The antenna at resonance on 40 and 80 is about 20 ohms which I match with a toroidal autoformer. Then 2 feet of coax to the TS480HX. 73, H. NQ5H |
H. Adam Stevens, NQ5H wrote:
The current below the loading coil is as if the antenna were full length, max power radiated; the voltage above the loading coil is as if the antenna were full length. That's semi-close but not entirely true. As Tom and Roy say, the coil indeed does distort the current away from the cosine pattern common in 1/4WL wire antennas. It just doesn't distort the current as much as they say. But the current at the top of the coil is a greater magnitude than it would be if your above statement were true. In one case, it is 66% higher than in a wire antenna. The current at the top of the coil is greater than it would be for the same stinger mounted on a physical 1/4WL antenna but it is not equal to the current at the bottom of the coil. The coil probably causes a larger phase angle between the voltage and current than exists in a wire antenna. If theta is small, V*I*cos(theta) can be fixed while V and I become larger than they are in a wire antenna. There's a lot happening around that coil. Remember the boundary conditions; the current is max at the feedpoint and zero at the end (can't go anywhere). Sorry, the current is not max at the feedpoint. There is a current maximum point located inside the coil that is a greater magnitude than the feedpoint current. If we say there is 90 degrees from current max inside the coil to the tip of the antenna, a center-loaded mobile antenna is longer than 90 degrees. One in particular, calculates out to be 110 degrees long. The coil causes an impedance discontinuity at each end in the standing- wave antenna. It is somewhat like the following where the 10k ohm feedline represents the coil with a Z0=SQRT(L/C): ---600 ohm feedline---+---10k ohm feedline---+---600 ohm feedline---open One can see that there would be reflections in both directions at the '+' points. That's why there will probably never be an equation to represent a mobile antenna. Here's the key. (Vfor+Vref) must be in phase with (Ifor+Iref) at the feedpoint for the feedpoint impedance to be purely resistive. But Vfor doesn't necessarily have to be in phase with Ifor for that to happen. Neither does Vref necessarily have to be in phase with Iref for that to happen. The coil has a different phase effect on voltage than it does on current and the natural Z0 of a vertical antenna is not fixed since every point on the antenna is a different distance from ground. It's probably impossible to quantify using equations. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Cecil Moore wrote:
Seems everyone must be suffering from post tramatic syndrome on this one. Here's the bottom line. Does a center-loaded mobile antenna have a cosine current distribution? No. Does just the coil have a cosine current distribution? Close to one but it may not start at zero degrees like a thin-wire dipole does. Does displacement current have an effect? Yes, but the effect is close to the same for the forward current and reflected current. Do I^2*R losses have an effect? Yes, but the effect is close to the same for the forward current and reflected current. Does radiation "loss" have an effect? Yes, but the effect is close to the same for the forward current and reflected current. Whatever effects exist that affect the current, the forward current and reflected current are affected close to equally. The net current anywhere on the antenna is still the phasor sum of whatever forward current and reflected current exists at that point. Any phase shift through the coil is multiplied by two by the two currents traveling in opposite directions with opposite rotations. Can one subtract the number of degrees occupied by the conductors from 90 degrees to get the number of degrees occupied by the coil? No, it's not that simple. Is the current at the top of the coil higher than predicted by the above simple calculation? Yes. Does the coil occupy zero degrees? No. If the coil doesn't occupy zero degrees, the net current at the bottom of a coil and at the top of the coil cannot be the same value when the coil is located in the middle of an electrical 1/4WL antenna. Are there special cases where the magnitude of the current at the top and bottom of a coil can be equal? Of course, but the typical loaded mobile antenna is not one of those special cases! -- 73, Cecil, W5DXP ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Cec sez,
My solution is to get Reg to write a new program. :-) ======================================= My patience is wearing thin. Nevertheless, once more into the breach. There's no need to write a new program. There's not even any need for an old one. Knowledge of the current distribution along a loading coil has no practical use except to assist with drawing pictures of it in books and magazines. FOR PRESENT PURPOSES THE LENGTH AND IMPEDANCE OF THE ANTENNA BELOW THE COIL IS NOT RELEVANT. IT CAN BE CONSIDERED TO BE PART OF THE GENERATOR. LET THE ANGULAR LENGTH OF THE COIL = THETA DEGREES. OTHERWISE KNOWN AS THE PHASE SHIFT. THIS IS A FIXED, IMMUTABLE QUANTITY SET BY THE PROPAGATION VELOCITY = 1 / SQRT( L * C ). THE MAGNITUDE OF THE CURRENT DISTRIBUTION ALONG THE COIL IS ALWAYS THE SAME COSINE CURVE BUT WHICH IS TRUNCATED (SLICED OFF) AT VARYING ANGULAR DEGREES AT EITHER OR BOTH ENDS. THE ANGLE AT WHICH THE TOP END IS TRUNCATED DEPENDS ON THE INPUT IMPEDANCE OF THE ANTENNA ABOVE IT. IT IS ALSO RELATED TO Zo OF THE COIL WHICH IS THE USUAL SQRT( L / C ). THE ANGLE AT WHICH THE BOTTOM END IS TRUNCATED IS ALWAYS THE TOP ANGLE MINUS THETA. IT CANNOT BE ANYTHING ELSE. THUS, WHEN THE TOP END IS OPEN CIRCUIT AND THETA = 90 DEGREES WE HAVE A COMPLETE 1/4-CYCLE OF A COSINE CURVE - A 1/4-WAVE RESONANT HELICAL ANTENNA. The foregoing applies to both short, fat coils and long, thin coils, close-wound or stretched-out. Coil resistance is the uniformly-distributed radiation resistance plus conductor resistance. For useful calculations such as Q, bandwidth, efficiency, etc., you can forget all about bewildering reflections, standing waves, forward and reflected power and use the well-known classical transmission line formulae, the everyday tools of all good engineers. The final wanted characteristic, the radiation pattern, can be found with number-crunching EZNEC-type computer programs which work in an entirely different manner. ---- Reg, G4FGQ |
Reg Says:
Knowledge of the current distribution along a loading coil has no practical use except to assist with drawing pictures of it in books and magazines. WROOOONG! Have you ever tried antenna shootouts? Cecil can enlighten you about the difference in efficiency and signal levels radiated by various configurations (bottom, center, top loading). The efficiency is proportional to the AREA under the current curve on the loaded radiator. That is dependent on the position of the loading element within the radiator. That also depends on the current distribution (drop :-) across the coil. Use that in the loaded parasitic element beams and the effect is magnified. So obvious, but hard to swallow for Rauchians? Viva Bush!!! Sayonara sKerry botoxed flipflopping lying girlie man. Yuri, K3BU.us |
Reg
Your patience is that of a saint. H. "Reg Edwards" wrote in message ... Cec sez, My solution is to get Reg to write a new program. :-) ======================================= My patience is wearing thin. Nevertheless, once more into the breach. There's no need to write a new program. There's not even any need for an old one. Knowledge of the current distribution along a loading coil has no practical use except to assist with drawing pictures of it in books and magazines. FOR PRESENT PURPOSES THE LENGTH AND IMPEDANCE OF THE ANTENNA BELOW THE COIL IS NOT RELEVANT. IT CAN BE CONSIDERED TO BE PART OF THE GENERATOR. LET THE ANGULAR LENGTH OF THE COIL = THETA DEGREES. OTHERWISE KNOWN AS THE PHASE SHIFT. THIS IS A FIXED, IMMUTABLE QUANTITY SET BY THE PROPAGATION VELOCITY = 1 / SQRT( L * C ). THE MAGNITUDE OF THE CURRENT DISTRIBUTION ALONG THE COIL IS ALWAYS THE SAME COSINE CURVE BUT WHICH IS TRUNCATED (SLICED OFF) AT VARYING ANGULAR DEGREES AT EITHER OR BOTH ENDS. THE ANGLE AT WHICH THE TOP END IS TRUNCATED DEPENDS ON THE INPUT IMPEDANCE OF THE ANTENNA ABOVE IT. IT IS ALSO RELATED TO Zo OF THE COIL WHICH IS THE USUAL SQRT( L / C ). THE ANGLE AT WHICH THE BOTTOM END IS TRUNCATED IS ALWAYS THE TOP ANGLE MINUS THETA. IT CANNOT BE ANYTHING ELSE. THUS, WHEN THE TOP END IS OPEN CIRCUIT AND THETA = 90 DEGREES WE HAVE A COMPLETE 1/4-CYCLE OF A COSINE CURVE - A 1/4-WAVE RESONANT HELICAL ANTENNA. The foregoing applies to both short, fat coils and long, thin coils, close-wound or stretched-out. Coil resistance is the uniformly-distributed radiation resistance plus conductor resistance. For useful calculations such as Q, bandwidth, efficiency, etc., you can forget all about bewildering reflections, standing waves, forward and reflected power and use the well-known classical transmission line formulae, the everyday tools of all good engineers. The final wanted characteristic, the radiation pattern, can be found with number-crunching EZNEC-type computer programs which work in an entirely different manner. ---- Reg, G4FGQ |
Yuri Blanarovich wrote:
Reg Says: Knowledge of the current distribution along a loading coil has no practical use except to assist with drawing pictures of it in books and magazines. WROOOONG! Have you ever tried antenna shootouts? Cecil can enlighten you about the difference in efficiency and signal levels radiated by various configurations (bottom, center, top loading). The efficiency is proportional to the AREA under the current curve on the loaded radiator. That is dependent on the position of the loading element within the radiator. That also depends on the current distribution (drop :-) across the coil. Use that in the loaded parasitic element beams and the effect is magnified. So obvious, but hard to swallow for Rauchians? Viva Bush!!! Sayonara sKerry botoxed flipflopping lying girlie man. Yuri, K3BU.us If you're really interested in the "AREA under the current curve," you'll have to figure out how to make an efficient, continuously loaded, short antenna. You'll find, though, that the difference between a continuously loaded antenna and an antenna with the loading coil, say, halfway up from the feedpoint won't amount to a hill of beans. There's still no such thing as a "current drop." 73, Tom Donaly, KA6RUH |
Reg Edwards wrote:
Cec sez, My solution is to get Reg to write a new program. :-) ======================================= My patience is wearing thin. Nevertheless, once more into the breach. There's no need to write a new program. There's not even any need for an old one. Knowledge of the current distribution along a loading coil has no practical use except to assist with drawing pictures of it in books and magazines. FOR PRESENT PURPOSES THE LENGTH AND IMPEDANCE OF THE ANTENNA BELOW THE COIL IS NOT RELEVANT. IT CAN BE CONSIDERED TO BE PART OF THE GENERATOR. LET THE ANGULAR LENGTH OF THE COIL = THETA DEGREES. OTHERWISE KNOWN AS THE PHASE SHIFT. THIS IS A FIXED, IMMUTABLE QUANTITY SET BY THE PROPAGATION VELOCITY = 1 / SQRT( L * C ). THE MAGNITUDE OF THE CURRENT DISTRIBUTION ALONG THE COIL IS ALWAYS THE SAME COSINE CURVE BUT WHICH IS TRUNCATED (SLICED OFF) AT VARYING ANGULAR DEGREES AT EITHER OR BOTH ENDS. THE ANGLE AT WHICH THE TOP END IS TRUNCATED DEPENDS ON THE INPUT IMPEDANCE OF THE ANTENNA ABOVE IT. IT IS ALSO RELATED TO Zo OF THE COIL WHICH IS THE USUAL SQRT( L / C ). THE ANGLE AT WHICH THE BOTTOM END IS TRUNCATED IS ALWAYS THE TOP ANGLE MINUS THETA. IT CANNOT BE ANYTHING ELSE. THUS, WHEN THE TOP END IS OPEN CIRCUIT AND THETA = 90 DEGREES WE HAVE A COMPLETE 1/4-CYCLE OF A COSINE CURVE - A 1/4-WAVE RESONANT HELICAL ANTENNA. The foregoing applies to both short, fat coils and long, thin coils, close-wound or stretched-out. Coil resistance is the uniformly-distributed radiation resistance plus conductor resistance. For useful calculations such as Q, bandwidth, efficiency, etc., you can forget all about bewildering reflections, standing waves, forward and reflected power and use the well-known classical transmission line formulae, the everyday tools of all good engineers. The final wanted characteristic, the radiation pattern, can be found with number-crunching EZNEC-type computer programs which work in an entirely different manner. ---- Reg, G4FGQ For a guy who is always excoriating people for believing old wives tales, you've just told a whopper, Reg. It's true, you might get an answer using the above theory that is "good enough for who it's for," but as an expression of what's actually happening in the antenna, it's hopelessly simplistic. 73, KA6RUH |
H. Adam Stevens, NQ5H wrote:
Reg Your patience is that of a saint. H. "Reg Edwards" wrote in message ... Cec sez, My solution is to get Reg to write a new program. :-) ======================================= My patience is wearing thin. Nevertheless, once more into the breach. There's no need to write a new program. There's not even any need for an old one. Knowledge of the current distribution along a loading coil has no practical use except to assist with drawing pictures of it in books and magazines. FOR PRESENT PURPOSES THE LENGTH AND IMPEDANCE OF THE ANTENNA BELOW THE COIL IS NOT RELEVANT. IT CAN BE CONSIDERED TO BE PART OF THE GENERATOR. LET THE ANGULAR LENGTH OF THE COIL = THETA DEGREES. OTHERWISE KNOWN AS THE PHASE SHIFT. THIS IS A FIXED, IMMUTABLE QUANTITY SET BY THE PROPAGATION VELOCITY = 1 / SQRT( L * C ). THE MAGNITUDE OF THE CURRENT DISTRIBUTION ALONG THE COIL IS ALWAYS THE SAME COSINE CURVE BUT WHICH IS TRUNCATED (SLICED OFF) AT VARYING ANGULAR DEGREES AT EITHER OR BOTH ENDS. THE ANGLE AT WHICH THE TOP END IS TRUNCATED DEPENDS ON THE INPUT IMPEDANCE OF THE ANTENNA ABOVE IT. IT IS ALSO RELATED TO Zo OF THE COIL WHICH IS THE USUAL SQRT( L / C ). THE ANGLE AT WHICH THE BOTTOM END IS TRUNCATED IS ALWAYS THE TOP ANGLE MINUS THETA. IT CANNOT BE ANYTHING ELSE. THUS, WHEN THE TOP END IS OPEN CIRCUIT AND THETA = 90 DEGREES WE HAVE A COMPLETE 1/4-CYCLE OF A COSINE CURVE - A 1/4-WAVE RESONANT HELICAL ANTENNA. The foregoing applies to both short, fat coils and long, thin coils, close-wound or stretched-out. Coil resistance is the uniformly-distributed radiation resistance plus conductor resistance. For useful calculations such as Q, bandwidth, efficiency, etc., you can forget all about bewildering reflections, standing waves, forward and reflected power and use the well-known classical transmission line formulae, the everyday tools of all good engineers. The final wanted characteristic, the radiation pattern, can be found with number-crunching EZNEC-type computer programs which work in an entirely different manner. ---- Reg, G4FGQ If patience were money, Reg would be wearing a barrel. 73, Tom Donaly, KA6RUH |
If you're really interested in the "AREA under the current curve," you'll have to figure out how to make an efficient, continuously loaded, short antenna. You'll find, though, that the difference between a continuously loaded antenna and an antenna with the loading coil, say, halfway up from the feedpoint won't amount to a hill of beans. There's still no such thing as a "current drop." 73, Tom Donaly, KA6RUH You are flying in a dreamland. Check the results of shootouts comparing Haasticks and other continuously loaded antennas vs. Bugcatchers or top loaded. You guys get your noses out of the books and check the reality. 73 Yuri |
Reg, G4FGQ wrote:
"For present purposes the length and impedance of the antenna below the coil is not relevant. It can be part of the generator." I infer that Reg is saying that at a particular frequency, a loading coil has a unique voltage across and a unique current through it. Probably sometimes so, but the simple argument was that the current at the coil ends can be different. This is caused by superposition of forward and reflected waves. The same power may have any number of voltage to current ratios (impedances). The purpose of a loading coil is to transform an antenna impedance to an impedance more compatible with a radio. There is a difference in impedance between the ends of a loading coil so that the current at its ends are different. The length and impedance of the antenna below the coil participate in the imbalance seen at opposite ends of the loading coil. The height of the loading coil on an antenna is thus significant. The length and impedance of the antenna below the coil participates in radiation. The function of a transmission line is to convey energy. The function of an antenna is to radiate energy. Radiation is a function of unbalanced current and the length through which it travels (page 864, Terman`s 1955 edition). The current per unit length below a loading coil is higher than above the coil. More radiation per unit length results from more current. This affects impedance at the coil ends. "For present purposes" we may declare anything so long as we don`t define our purposes, but Fig 9-22 on page 9-15 of ON4UN`s "Low-Band DXing" is significant and no one has said his pictures are wrong and given reasons. Best regards, Richard Harrison, KB5WZI |
Yuri Blanarovich wrote:
If you're really interested in the "AREA under the current curve," you'll have to figure out how to make an efficient, continuously loaded, short antenna. You'll find, though, that the difference between a continuously loaded antenna and an antenna with the loading coil, say, halfway up from the feedpoint won't amount to a hill of beans. There's still no such thing as a "current drop." 73, Tom Donaly, KA6RUH You are flying in a dreamland. Check the results of shootouts comparing Haasticks and other continuously loaded antennas vs. Bugcatchers or top loaded. You guys get your noses out of the books and check the reality. 73 Yuri I wrote that you'd have to make an _efficient_, continuously loaded, short antenna if you want to get the most area under the curve. That's easier said than done. Certainly, you can't do it. So a shootout is your idea of a reliable antenna test. I guess it's no worse than using fish tank thermometers to measure efficiency. 73, Tom Donaly, KA6RUH |
Reg Edwards wrote:
W5DXP wrote: My solution is to get Reg to write a new program. :-) My patience is wearing thin. Reg, the smiley face means it was a joke. Is you patience wearing thin concerning my feeble attempts at humor? :-) THE MAGNITUDE OF THE CURRENT DISTRIBUTION ALONG THE COIL IS ALWAYS THE SAME COSINE CURVE BUT WHICH IS TRUNCATED (SLICED OFF) AT VARYING ANGULAR DEGREES AT EITHER OR BOTH ENDS. Yep, I previously guessed the SQRT(L/C) would be very high for a large coil. After using your Solonoid program, it seems my guess was much too high. The Z0 of the coil seems to be more like 1k-2k than the 10k I first guessed. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Tom Donaly wrote:
You'll find, though, that the difference between a continuously loaded antenna and an antenna with the loading coil, say, halfway up from the feedpoint won't amount to a hill of beans. Wrong! Bragging rights after a 75m shootout are worth a lot more than a hill of beans. A helical antenna has NEVER beaten a center- loaded antenna in a 75m shootout. And in fact, my junk box *top- loaded* antenna beat all the center-loaded bugcatchers in one of the CA shootouts. The current below the coil is the highest current in the average 75m mobile antenna. The longer that uninhibited section is, the stronger the radiated signal, thus my success in the shootout. My bottom section was about ten feet long, then a horizontal coil and horizontal top hat. I'm going to refine that configuration when I get time. There's still no such thing as a "current drop." The decrease (drop) in current across a loading coil installed in a standing-wave antenna does NOT in any way violate Kirchhoff's current law. One can imply from Kirchhoff's current law that there is no current decrease (drop) across a point. I don't know anyone who disagrees with that so any argument is just a straw man. Kirchhoff never said the current at one point in a network had to equal the current at another point in the network. Many patches have been added to the DC circuit model to try to adapt it to RF networks. Some function after a fashion and some fail utterly. We all need to be able to recognize the difference. For EM waves, the E-field and H-field are often affected in the same way. Saying that the E-field voltage drops but the H-field current doesn't drop is simply nonsense. Likewise, saying that the H-field current flows and the E-field voltage doesn't flow is nonsense. The E-field and H-field are usually inseparable. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Tom Donaly wrote:
For a guy who is always excoriating people for believing old wives tales, you've just told a whopper, Reg. It's true, you might get an answer using the above theory that is "good enough for who it's for," but as an expression of what's actually happening in the antenna, it's hopelessly simplistic. For this discussion, the magnitude of radiation is irrelevant except as it relates to "losses" from the system. So please enlighten us as to "what's actually happening" to the standing-wave current "in the antenna". -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
On Wed, 03 Nov 2004 12:50:53 -0600, Cecil Moore
wrote: magnitude of radiation is irrelevant in an antenna forum, this is ludicrous. |
On Wed, 03 Nov 2004 12:47:59 -0600, Cecil Moore
wrote: current across a loading coil installed in a standing-wave antenna does NOT in any way violate Kirchhoff's current law. There is no such law of a current into anything but a point (both dimensionless and componentless). |
Yuri Blanarovich wrote:
Check the results of shootouts comparing Haasticks and other continuously loaded antennas vs. Bugcatchers or top loaded. Good idea, Yuri. Rename Hamsticks to Hahasticks. :-) -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Richard Harrison wrote:
There is a difference in impedance between the ends of a loading coil so that the current at its ends are different. Good point, Richard. Why isn't anyone arguing that the current on each side of a loading coil in an antenna tuner is equal? It can easily be proven to be different using a Smith Chart. "For present purposes" we may declare anything so long as we don`t define our purposes, but Fig 9-22 on page 9-15 of ON4UN`s "Low-Band DXing" is significant and no one has said his pictures are wrong and given reasons. I haven't seen that book, but I have seen reproductions of his diagrams on the net. The situation is not as simple as asserting that the coil occupies the number of degrees not occupied by the vertical sections. As usual, the facts lie somewhere in between the two rail arguments. 1. The currents at each end of the coil are not equal. (shoots down rail #1 argument) 2. The current distribution over the entire loaded mobile antenna is not a standing cosine wave. (shoots down rail #2 argument) Since the coil is a different characteristic impedance than the vertical sections, there exist reflections, both ways, from each end of the coil. Taking four additional sets of reflections into account mathematically is extremely difficult. That's probably why nobody has ever attempted it. However, a bugcatcher antenna can be approximated by the following: ---600 ohm feedline---+---1600 ohm feedline---+---600 ohm feedline---open bottom section loading coil top section By modeling with EZNEC, I am attempting to ascertain the VF of the loading coil. That's the only thing standing in the way of a conventional analysis. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Tom Donaly wrote:
So a shootout is your idea of a reliable antenna test. Before you dismiss those efforts, I suggest you find out who was involved in the design of the measurements. (Hint: It wasn't me) -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Richard Clark wrote:
Cecil Moore wrote: magnitude of radiation is irrelevant in an antenna forum, this is ludicrous. Sorry, I thought the meaning was clear. The "magnitude of radiation is irrelevant" to the argument which is confined to current through a loading coil. You must be getting senile, Richard. You keep forgetting what the argument is all about. I trust that's not a deliberate diversion. :-) -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Richard Clark wrote:
Cecil Moore wrote: current across a loading coil installed in a standing-wave antenna does NOT in any way violate Kirchhoff's current law. There is no such law of a current into anything but a point (both dimensionless and componentless). My "point" exactly!!! A bugcatcher coil is NOT a point. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Cecil Moore wrote:
Tom Donaly wrote: You'll find, though, that the difference between a continuously loaded antenna and an antenna with the loading coil, say, halfway up from the feedpoint won't amount to a hill of beans. Wrong! Bragging rights after a 75m shootout are worth a lot more than a hill of beans. A helical antenna has NEVER beaten a center- loaded antenna in a 75m shootout. And in fact, my junk box *top- loaded* antenna beat all the center-loaded bugcatchers in one of the CA shootouts. The current below the coil is the highest current in the average 75m mobile antenna. The longer that uninhibited section is, the stronger the radiated signal, thus my success in the shootout. My bottom section was about ten feet long, then a horizontal coil and horizontal top hat. I'm going to refine that configuration when I get time. There's still no such thing as a "current drop." The decrease (drop) in current across a loading coil installed in a standing-wave antenna does NOT in any way violate Kirchhoff's current law. One can imply from Kirchhoff's current law that there is no current decrease (drop) across a point. I don't know anyone who disagrees with that so any argument is just a straw man. Kirchhoff never said the current at one point in a network had to equal the current at another point in the network. Many patches have been added to the DC circuit model to try to adapt it to RF networks. Some function after a fashion and some fail utterly. We all need to be able to recognize the difference. For EM waves, the E-field and H-field are often affected in the same way. Saying that the E-field voltage drops but the H-field current doesn't drop is simply nonsense. Likewise, saying that the H-field current flows and the E-field voltage doesn't flow is nonsense. The E-field and H-field are usually inseparable. Ahm still ignorin' you, Cecil. You don't actually read posts, you just respond to what you think they ought to mean in order to be able to say whatever you've just made up in your head. 73, Tom Donaly, KA6RUH |
Good point, Richard. Why isn't anyone arguing that the current on each side of a loading coil in an antenna tuner is equal? It can easily be proven to be different using a Smith Chart. I mentioned way back too, question for Rauchians: How come we get RF current drop across the RF choke, hmmm? Or Are you going to argue that it is the same at both ends? Extreme case but proves the point. Get your "books" out, say it ain't so and look even more foolish. I like the Hahastick :-) Yea, should have been Hamstick. Yuri, K3BU.us Viva Bush! |
On Wed, 03 Nov 2004 13:39:57 -0600, Cecil Moore
wrote: current across a loading coil installed in a standing-wave antenna does NOT in any way violate Kirchhoff's current law. There is no such law of a current into anything but a point (both dimensionless and componentless). My "point" exactly!!! A bugcatcher coil is NOT a point. Hence, the first statement above was a troll. |
On Wed, 03 Nov 2004 13:37:50 -0600, Cecil Moore
wrote: The "magnitude of radiation is irrelevant" to the argument which is confined to current through a loading coil. Which is a ludicrous observation in an antenna forum. |
Tom Donaly wrote:
Ahm still ignorin' you, Cecil. You don't actually read posts, ... Actually, I do read the posts and respond mostly to the old wives tales. You and I probably agree on 99% of the physics. It's that other one per- cent of physics based on old wives' shortcuts to which I object. Shortcuts are NOT the laws of physics!!! Hint: Every shortcut has a shortcoming. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Yuri Blanarovich wrote:
Good point, Richard. Why isn't anyone arguing that the current on each side of a loading coil in an antenna tuner is equal? It can easily be proven to be different using a Smith Chart. I mentioned way back too, question for Rauchians: How come we get RF current drop across the RF choke, hmmm? Or Are you going to argue that it is the same at both ends? Extreme case but proves the point. Get your "books" out, say it ain't so and look even more foolish. I like the Hahastick :-) Yea, should have been Hamstick. Yuri, K3BU.us Viva Bush! Since when has anyone claimed it's impossible to make a coil that has a non-constant current distribution? You guys sure go out of your way to pat yourselves on the back for proving something no one has ever argued about. For those who really want to learn about loading coils on small antennas, go to Tom Rauch's web page and learn how a real engineer deals with the problem. 73, Tom Donaly, KA6RUH |
| All times are GMT +1. The time now is 01:27 PM. |
Powered by vBulletin® Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
RadioBanter.com