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Aerial grounding and QRM pick-up: theory & practice
On 22 Sep, 16:47, art wrote:
On 22 Sep, 16:02, "Richard Fry" wrote: "art" wrote O.K. I may have muddied things. I hold to the fact that a one wavelength dipole will always radiate at a higher efficiency than a 1/2 wave dipole. _________ Please post your definition of "efficiency," in this context. RF Power in vs power out of a system. I know how to do this for a parallel circuit ala a tank circuit where energy is released in equilibrium fashion. For a half wave dipole you can't have two energy containers so you may or may not be heading for excess end effects because of high voltage looking for where it has to go. (Personally I don't know how a half wave radiates because that form vuews the cyclic current continually radiating as the time variant which is contrary to all other radiations i.e. a spark plug, ahydregen bomb which is a bigger container that a flyback transformer and a bigger container will always beat a small container with respect to out going accelleration of energy, particles or plasma which ever you may prefer)without any known proof.I believe that is why the quad was designed to get away from the spark plug type emmissions at the ends of the radiator. On the other side of the coin, since both a quad and a 1/2 wave dipole is assumed to be suitable drivers for a yagi array both must be bi directional so gain is applicable when comparing these radiators I would would think! Best regards Art Richard , I have been reviewing antenna fundamentals as per the engineering handbook by Jasik second edition where it states "The method of computing radiation patterns foir thin linear radiators is basic regardless of length or complexity of shape " if one assumes that the current from point to point is sinosoidal. This statment is consistent with the present assumption that the time variant current is sinosoidal at every point along the length of the antenna. Well I have clearly shown for a parallel circuit you cannot pursue this assumption anymore even tho the books state otherwise. The books are not incorrect if the mathematics produced by such a assumption is correct which mathematicians often do when there is an absence of knoweledge to the contrary. What I am declaring is the tank circuit ala parallel circuit which demands a full wave length antenna is the most efficient because the assumption by mathematicians is incorrect. Following Gauss's laws for static and enlarging the format to a dinamic situation i.e. time varient then the demand is for a arrangement in "equilibrium" which cannot be attained with anything other that a full wave length. Following this logic mathematically it concurrs with Maxwells laws and any computor program will move away from any half wave radiator if you ask for maximum gain and allow it to computeaway from a planar arrangement under Maxwells laws.( By the way I always refer to a full wavelength radiator which by no means infers a center feed. In my case I usually follow the end fed aproach because of a dual windings but in opposite directions) If Maxwell had in his portfolio an expanded Gaussuian law for making his jigsaw complete the overall picture would have been completed in no time. Unfortunately he did not have this at hand but instead used Faraday and others input to arrive at the correct answer but with gaps in the info provided. It is for that reason I persued this analogy which is new and contrary with existing assumptions even tho the eventual answers are the same. BUT the analogy of assumption of time varient current of itself produces radiation is incorrect at least for a parallel circuit, aspark plug with a flyback transformer or even the emmisions of a nuclear explosion. I don't think there is a need to dither on the subject anymore since nobody knows how a fractional wavelength antenna really works whereas I am promoting a view of an arrangement in equilibrium and the commonly used approach by Gauss and others with respect to a closed arbitary field. Enjoyed the discussion tho, very thought provoking. Regards Art antennas |
Aerial grounding and QRM pick-up: theory & practice
On Sep 22, 5:40 pm, art wrote:
O.K. I may have muddied things. I hold to the fact that a one wavelength dipole will always radiate at a higher efficiency than a 1/2 wave dipole. If it does, I doubt it's enough to measure on the air.. The example I gave as for an instance was a quad versus a 1/2 wave dipole. This is readily seen by any operator empirically. I've never seen it here. For that reason, I hardly use loops. Neither vertically oriented, or horizontal as for NVIS use. I don't see them as worth the extra trouble. Being I tested them on 75m using NVIS paths, a noticable difference in efficiency should have been readily apparent. It wasn't. In fact, I usually has slightly better performance using the dipoles, which I think was due to the bulk of the max current portions of the antenna being higher above ground in general. The loop sagged a bit in areas, and wasn't all that high above ground. The more wire near the ground, the more ground loss in general. Mathematically it is proven that way also even tho both are in accordance to Maxwell's laws. Where is the math? You should find a very slight difference at best.. It's common knowledge that even a short piece of wire 1/10 of a wave long will radiate nearly all the power that is applied to it. You can go lots shorter than that if you want. If even a short piece of wire will radiate nearly all the power applied to it, what is the point on harping about some magical properties of a full wave length of wire? Art, you are starting to bark at the moon I'm afraid... I was going to comment on some of your other posts, but I think I'll spare you the increase in blood pressure. All I can say is that you are starting to wander off in mumbo jumbo land again.. Replacing known science with conjured mumbo jumbo is no way to live. MK |
Aerial grounding and QRM pick-up: theory & practice
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Aerial grounding and QRM pick-up: theory & practice
If you'll look back at some of Art's postings, you'll see that he
consistently uses the word "efficiency" in a way that's contrary to the universally accepted definition. His meaning of the word is more like gain, but sometimes including communication effectiveness in some way. In fishing through earlier postings, you'll also see that I implored him many times to either use such words as they're universally understood, or else explicitly define what he means by them. The reason for the requests was to help him communicate what he was trying to say, rather than leave a trail of misunderstanding and confusion. All my requests did, however, was make him intensely angry with me, and no definitions were given or change in usage made. I hope this recent round of requests for clarification will have more effect than I was ever able to accomplish. Roy Lewallen, W7EL |
Aerial grounding and QRM pick-up: theory & practice
"art" wrote
I don't think there is a need to dither on the subject anymore since nobody knows how a fractional wavelength antenna really works Read Kraus' "Antennas...," 3rd edition, Section 2-12 and related text. |
Aerial grounding and QRM pick-up: theory & practice
On 22 Sep, 20:36, Walter Maxwell wrote:
On Sat, 22 Sep 2007 19:19:18 -0700, wrote: On Sep 22, 5:40 pm, art wrote: O.K. I may have muddied things. I hold to the fact that a one wavelength dipole will always radiate at a higher efficiency than a 1/2 wave dipole. If it does, I doubt it's enough to measure on the air.. The example I gave as for an instance was a quad versus a 1/2 wave dipole. This is readily seen by any operator empirically. I've never seen it here. For that reason, I hardly use loops. Neither vertically oriented, or horizontal as for NVIS use. I don't see them as worth the extra trouble. Being I tested them on 75m using NVIS paths, a noticable difference in efficiency should have been readily apparent. It wasn't. In fact, I usually has slightly better performance using the dipoles, which I think was due to the bulk of the max current portions of the antenna being higher above ground in general. The loop sagged a bit in areas, and wasn't all that high above ground. The more wire near the ground, the more ground loss in general. Mathematically it is proven that way also even tho both are in accordance to Maxwell's laws. Where is the math? You should find a very slight difference at best.. It's common knowledge that even a short piece of wire 1/10 of a wave long will radiate nearly all the power that is applied to it. You can go lots shorter than that if you want. If even a short piece of wire will radiate nearly all the power applied to it, what is the point on harping about some magical properties of a full wave length of wire? Art, you are starting to bark at the moon I'm afraid... I was going to comment on some of your other posts, but I think I'll spare you the increase in blood pressure. All I can say is that you are starting to wander off in mumbo jumbo land again.. Replacing known science with conjured mumbo jumbo is no way to live. MK Art, it distresses me to read the misleading statements you profess to be true in your posts. There is no difference in the 'efficiencies' between a full-wave and a half-wave dipole. Let's assume the wire size and conductivity of each dipole is such that we can say they both radiate 98 percent of the power delivered to them. Let's also say that the same amount of power is delivered to both dipoles. What now is the difference in the radiation between the two dipoles? snip Walt. I have no problem with Maxwells laws but I do have a problem with a mathematical stunt to measure radiation of a half wave dipole based on one having to accept that at all points on the radiator the current is sinosoidal. There is no distinct analysis with the specifics of radiation. period. Using a parallel circuity ala tank circuit insights are produced that radiation is created by the shorted energy containers of capacitance and inductance which is an intrinsic part of any radiator in distributed form. The tank circuit is well documented. So the question now becomes, at least for full understanding of radiation is how does a half wave radiator follow the format shown by a spark plug with a flyback transformer or a full wave radiator or even the blast from a nuclear bomb? Yes, a half wave antenna also has distributed inductance and capacitance energy containers but how is the mechanism shown by the tank circuit implimented when the arrangement is not in equilibrium? Now I think I know what happens but I am interested in contrary thoughts from those skilled in the arts without the retoric. As an aside, why does computor programs drift away from planar form radiators as well to full wave radiators when the computor is asked to compute for maximum gain? Is this like the quadratic equation with four answers where you get to determine the imaginary answers? I would suggest for starters those that are skilled in the art quantify the energy used for end effect radiation either in the normal atmosphere or in the rarified atmosphere of Quito Equador when Tesla type emmissions are visable? Without assumptions ofcourse!!!! Regards Art |
Aerial grounding and QRM pick-up: theory & practice
art wrote:
I hold to the fact that a one wavelength dipole will always radiate at a higher efficiency than a 1/2 wave dipole. What if the 1/2 wave dipole was made of super-conducting material, i.e. zero loss except for radiation? -- 73, Cecil http://www.w5dxp.com |
Aerial grounding and QRM pick-up: theory & practice
On 23 Sep, 07:29, "Jimmie D" wrote:
"art" wrote in message ups.com... On 22 Sep, 07:22, "Richard Fry" wrote: "art" wrote The most efficient radiator is one wave length long where it is considered to be in equilibrium with a parallel electrical cuircuit. For most efficient radiation both the capacitance and the inductance must act as a energy storage such that when the terminals are shorted the energy is released in a burst such that radiation can begin. ... In the case of a fractional wave length radiator the pendulum type radiation is not available for radiation ___________ Note (for one example of many) that in an antenna system consisting of a 1/2-wave, center-fed dipole driven by a matched, balanced transmission line, the dipole itself radiates virtually all of the r-f energy present at the antenna feedpoint. The radiation efficiency of a system as in the above example, but using a full wave dipole is no better than the 1/2-wave version, other things equal. The full wave version just has a different radiation pattern. RF I don't know what your credentials are for you to make such a statement but it is a free world after all! A quad radiator is a wave length radiator with a gain more than a half wave as one sample. Computor programing confirmes more radiation from full wave antennas and mathematics according to Maxwell,s rules substantiate it. I can understand not believing computor programs but I am very interested in any mathematical data that would support your stand which is contrary to the mathematics that I and others support. What you are stating is that an attena in a series cuircit format produces the same radiation as a parallel or tank cuircuit. I am more than eager to read the contrary mathematical proof that is contrary to the mathematics that I hold true. You may have hit on the true explaqnation of radiation which Einstein, Planck and many others went to their grave without solving it Regards Art KB9MZ.....XG I dont know his credentials either but Richard is absolutly correct. Efficency is the ability to radiate the signal and not turn it into infra-red energy and has nothing to do with gain. The Math: Efficiency = (power applied to the antenna system - power turned into heat by the antenna system)/power applied to the antenna system. Doesnt take a computer, doesnt take Maxwell or Einstien to explain. 5th grade math works pretty well in this case. The best thing the OP can do for his existing antenna is install a good ground system and impedance matching networks, antenna tuner. If I were really serious about it I would invest in an antenna analyzer so I would know when my antenna is tuned for optimum match to my radio and log the settings of my tuner. With the ground system and antenna type he has I am sure the ground resistance is soaking up most of his signal. He would surely benifit from improving his ground system. Jimmie- Hide quoted text - - Show quoted text - In comparing two antennas with similar omni direction radiation field I state that gain in the field is indicative of increased radiadion but that is a side issue brought up as often is in this newsgroup in tha absence of a point by point debate. That method of responding is pretty much used by all polititions. If you state what you THINK makes the "best antenna" from accurate empirical data then I have no problem with what you say, I just don't agree with it. I say that because you focussed on drive or feed impedance when it is well known that a matching impedand does not infer we have a matching impedance in the system. Am illustration of the point. The new touted antenna from Rohd island university proclames a shortened antenna with a 52 ohm matching impedance. Since a half wave antenna is not in equilibrium the energy for themissing half must go somewhere. In the case of the new antenbna the extra energy went back into the feed line and possibly could have radiated from there and not the antenna. The ground plane that you put forward infers that the ground plane is the other half of a equivalent full wave dipole, and it may well be if one can say that the ground plane radiates and prevents the ground wasting the energy. Personally I don't believe that ground radials radiate but that is O.K. So how is this new fangled antenna corrected to radiating efficiently. How is that done? The antenna uses an inductive turnsfor shortening a antena thatis not in equilibrium so to bring it into equilibrium you add a mirror immage of the antenna including the windings and connect the two at the top together with the image antenna wound over the initial antenna such that the extra indunct becomes balanced( not cancelled) and thus one can feed it at the two wire extremities. Now you have no end effects energy losses and the circulating current has no need to find a way to balance the circuit by seeking the ground or backtracking up the feed line.It takes no time at all to prove this with a small home made antenna and it is that what I was sugesting from the beginning. By the way this is exactly what the scientific community has been pursuing with the anttena therom of merging electrical and magnetic field as well as others. Until now nobody was aware that if Gauss had continued with his static theorem and enlargened it to a dinamic basis more information about radiation would be revealed with consequenct advances as to what creats or starts radiation rather than continueing with a situation founded on a assumption of which there is no proof. The theorem of an extended gaussian logical strategy to bring it into the format of radiation production destroys the present assumptions alluded to both in mathematical term and also in empirical terms without deviation from Maxwells laws with the extra proof that computor programs built around Maxwells laws also confirms the equilibrium position. Now I have no problem with people that all existing designs are better but for sure industry and the younger generation is not opposed in reviewing perceived improvements since they are not addicted to preventing change. The bottom line is that a person asked for info and it is upto him to choose which he will accept and one should not get into distress if counter information becomes chosen. Have a great day Regards Art KB9MZ |
Aerial grounding and QRM pick-up: theory & practice
Roy Lewallen wrote:
If you'll look back at some of Art's postings, you'll see that he consistently uses the word "efficiency" Oh, this thread had me a bit confused. I didn't see where you guys suddenly started taking about efficiency, where did that come from? Now Roy clears things up for me, it was due to a posting by "Art." See, Art is in my killfile, and my good old newsreader effectively clobbered his post. Art has been in my killfile for months now, permanently, because it always seemed whenever he posted something it resulted in a rash of waste-of-my time replies, of folks trying to straighten him out, and I don't think anyone ever has. So now that this thread has deteriorated..... "Aerial grounding" goes in my killfile. CUL. So that I don't get flamed too much, I will start a posting on a little project I am working on here, which is incomplete. I am titling it "Beverage antenna, feedline pickup." Rick K2XT |
Aerial grounding and QRM pick-up: theory & practice
On 23 Sep, 06:37, Cecil Moore wrote:
art wrote: I hold to the fact that a one wavelength dipole will always radiate at a higher efficiency than a 1/2 wave dipole. What if the 1/2 wave dipole was made of super-conducting material, i.e. zero loss except for radiation? -- 73, Cecil http://www.w5dxp.com Can you have a tank circuit without resistance? Is I sq R now not applicable anymore? Glad to see you commenting. Art |
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