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#1
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On 15 Feb, 15:29, (Richard Harrison) wrote:
Art wrote: "My present antenna, which is for 160 m and above, is about the size of two shoe boxes and is less than 2:1 swr (50 ohm) across the band when situated at the tip of my tower." Outstanding! An effective antenna needs to be an appreciable portion of wavelength in some dimension. If Art`s antenna is an appreciable portion of 525 feet it can radiate well on 160 meters. Any length of wire carrying an RF current is capable of radiation. ******* Yes, but it is not useable if C and L for the length involved and frequency of use is not adhered to. Implicit in Maxwell's laws is that a radiator can be any size or shape as long as it is in equilibrium. Without the inclusion of that last word all laws of the masters are invalid. Significant radiation from a short wire requires much current. With a garbage can lid for a reflector, a helical antenna can be made. Were it 3 feet across in diameter (0.9 meter) the helix might work on 3 meters as the diameter needs to be about 0,3 lambda. Terman gives helical antenna information on page 909 of his 1955 opus. His best bets for small antenas are the corner reflector and the Yagi. ###### It is not the physical size that is important whith respect to a dish it is the wavelength between the two objects that counts. A simple helix antenna can use a reflector in place of a ground plane not as an optical ray deflector.Such an array is not in a state of equilibrium Best regards, Richard Harrison, KB5WZI |
#2
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On Feb 15, 6:46 pm, art wrote:
On 15 Feb, 15:29, (Richard Harrison) wrote: Art wrote: "My present antenna, which is for 160 m and above, is about the size of two shoe boxes and is less than 2:1 swr (50 ohm) across the band when situated at the tip of my tower." Outstanding! An effective antenna needs to be an appreciable portion of wavelength in some dimension. If Art`s antenna is an appreciable portion of 525 feet it can radiate well on 160 meters. Any length of wire carrying an RF current is capable of radiation. ******* Yes, but it is not useable if C and L for the length involved and frequency of use is not adhered to. Implicit in Maxwell's laws is that a radiator can be any size or shape as long as it is in equilibrium. Without the inclusion of that last word all laws of the masters are invalid. Define equilibrium. As far as I can tell, you seem to infer that being in "equilibrium", means that it is resonant. I hate to break it to you, but being resonant is no sure road to efficiency as a radiator of RF. How many hundreds of feet of wound 22 gauge wire does this device contain? Seems to me, if I ponder all the laws of the "masters", you have reinvented an air cooled dummy load that probably won't handle too much power before it becomes so hot as to melt whatever is close to it. Maybe I suggest a Heathkit "Cantenna" as a better oil cooled substitute that can be ground mounted for ease of use. You can blast it with your 8877 for short periods of time, and I doubt it will melt any plastic that is lying next to it. Requires no tower, and no need for garbage can lids. According to the law of Art, it is in equilibrium, and should satisfy all the requirements of the masters, whoever they may be, and wherever they may lie. MK |
#3
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#4
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Art wrote:
"It is not physical size that is important with respect to a dish it is the wavelength between two objects that counts. A simple helix antenna can use a reflector in place of a ground plane not used as an optical ray reflector." Yes, but, size matters even when you are told it doesn`t. A dish usually makes the path length equal between its frontal plane and focal point for all rays by the parabolic curvature of its reflector. Everything stays in phase by virtue of traveling the same distance through the same medium. The bigger the dish, the higher the gain. On the helix antenna invented by Kraus, Terman writes on page 909 of his 1955 opus: "The directive gain is appreciable, a six-turn helix having a diameter of 0.30 lambda sith a spacing of 0.30 lambda between turns developing a gain of 45 when provided with a reflecting screen at the input and that is normal to the helix axis. A helical antenna is relatively broadband in its characteristics." Best regards, Richard Harrison, KB5WZI |
#5
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Gentlemen.
It is now over two weeks since Art made his offer to Denny to supply a model of his new antenna for testing, ( and should by now have been delivered ), which gives all the naysayers a last chance to nail their colours to the mast. For my part it is my belief that Art's antenna will be a major advance in the design of antenna's of the future, so, what say you gentlemen, do you agree, or disagree?. Just to make things even, it is my belief that someone, who has the respect of most ham's in this group,( including the indomitable Richard) has a finger in this pie. Derek. |
#6
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On Mar 4, 5:52 am, Derek wrote:
Gentlemen. It is now over two weeks since Art made his offer to Denny to supply a model of his new antenna for testing, ( and should by now have been delivered ), which gives all the naysayers a last chance to nail their colours to the mast. For my part it is my belief that Art's antenna will be a major advance in the design of antenna's of the future, so, what say you gentlemen, do you agree, or disagree?. Sorry, I don't believe in the tooth fairy, free lunches, or dummy loads on sticks. Or should I say dummy loads on towers... Just to make things even, it is my belief that someone, who has the respect of most ham's in this group,( including the indomitable Richard) has a finger in this pie. Well, Yoda is pretty good at what he does. But I doubt if even the force® can save this project. Like I have said, if I thought it was possible to achieve full size performance from a shoe box sized jumble of several hundred feet of thin 22 gauge wire, I would have already built one. But unfortunately, I have no such delusions of RF grandeur. BTW, if even both of the Richards, "I'm not sure which one you consider indomitable", had a finger in the pie, but the rest of the world refused to stick their finger in the pie, how would that make things even? Myself, I have trouble seeing either one of them falling for this fairy tale of full size antenna performance from a mini sized dummy load on a stick. Even if it is air cooled. Does this help clarify my stance on this small sized subject? I try to avoid any gray areas that might give the impression that I think this device even has a remote chance of it's claimed full sized success as a radiator of RF. But in case some still get confused by what I say, let me rephrase in a manner that most all will understand. What a load of horse manure says I... MK |
#7
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Derek wrote:
Gentlemen. It is now over two weeks since Art made his offer to Denny to supply a model of his new antenna for testing, ( and should by now have been delivered ), which gives all the naysayers a last chance to nail their colours to the mast. For my part it is my belief that Art's antenna will be a major advance in the design of antenna's of the future, so, what say you gentlemen, do you agree, or disagree?. Just to make things even, it is my belief that someone, who has the respect of most ham's in this group,( including the indomitable Richard) has a finger in this pie. Derek. There are people who will happily believe most anything without any credible evidence. Examples abound - believers in homeopathy, astrology, and alien abductions to name just a very few. Believers in Art's antenna claims are in this category. I'm not. Roy Lewallen, W7EL |
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