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On Fri, 19 Mar 2004 04:11:32 GMT, "Old Ed"
wrote: Oh, Cecil, Cecil, Cecil! If trees you seem to assume If only and if and if then I guess Good guess, but about what? 73's Richard Clark, KB7QHC |
Richard Clark wrote:
On Fri, 19 Mar 2004 04:11:32 GMT, "Old Ed" wrote: Oh, Cecil, Cecil, Cecil! If trees you seem to assume If only and if and if then I guess Good guess, but about what? Please look up "analogy" in the dictionary and "conditional statements" in a good logic book. And look up "emoticon" on the web. -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
Hi again -
I no longer aspire to cornering you into an unbiased comparison. I can see you're much too crafty for that! ;-) But I don't want you to think I'm easily fooled, either. So a couple more comments below... "Cecil Moore" wrote in message ... Old Ed wrote: 2. If trees are assumed to be available to support dipoles, then trees could be used to support a monopole. But trees absorb energy from the monopole which has no gain to waste. Trees absorb virtually no energy from a dipole. OK, we need to assume that you have a couple of trees that are 130+ feet apart, because you say you are using them to support a dipole of that length. So instead of a "T" between the trees where the top is a dipole and the vertical element is the feedline, why not a "T" between the trees where the top is a support rope and the vertical element is a monopole? Do you think a couple of trees 65+ feet away from said monopole would suck up all its radiated energy? And if so, why wouldn't they clobber the much closer, high-impedance ends of the dipole? BTW, I repeat that I'm NOT trying to convert you to a different antenna type; I'm merely advocating some technical objectivity when making comparisons. 3. As to the gain figure, you seem to assume that the dipole is always operating at the peak of one of its lobes, and never has to operate in one of its nulls. I never operate my antenna in a null. This is quite a remarkable feat! Do you only talk to a list of favored stations that are known to lie in your lobes? Or do you refuse to answer a list of stations that lie in your nulls? (Or if they're DEEP in a null, you might be unaware of their existence, I suppose.) I also don't drive my pickup one mile per hour even if I only average driving it one hour per day. Seems by your logic, I should always walk since I can walk faster than the average speed of my pickup over any 24 hour period. :-) I'm afraid this analogy is so strained and inapplicable that it doesn't really need a response. -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
Old Ed wrote:
"---trees could be used to support a monopole." Yes, but in supporting a monopole, the tree is more or less parallel, near, and lossy. Horizontal dipoles are somewhat perpendicular to trees which are likely to be in the nulls of the dipole pattern. Shortwaves are propagated effectively by bounce at the correct angle off the ionosphere. Propagation of shortwaves along the earth`s surface is seriously attenuated. Vertical antennas up to 5/8-wavelength launch their maximum signal along the earth`s surface, not good for skywave propagation in most cases. It works at sea where conductivity is excellent and over much greater distance than over land, so that not all shortwave tangential energy is necessarily wasted. Horizontal antennas produce no tangential aignal along highly conducting earth. The reflection at near zero elevation is equal and opposite in polarity and it cancels. High 1/2-wave dipoles (between 1/4-wave and 1/2-wave high) have gains at some angle between zero and 90-degrees as compared with the same dipole in free-space. A 1/2-wave dipole between 1/4-wave and 1/2-wave above good ground can have a dB or two gain at some elevation angle between 15 and 30-degrees. It`s not much, but it`s not a loss. Even over poor ground, the free-space 1/2-wave dipole characteristic is likely available at the useful elevation angle. I worked for years in shortwave broadcasting and have yet to see any facility which employed vertical transmitting antennas. I`ve heard there are some verticals, but when serious investment is professionally made in shortwave transmitting antennas it is nearly always made in the horizontally polarized variety. Best regards, Richard Harrison, KB5WZI |
Richard Harrison wrote, I worked for years in shortwave broadcasting and have yet to see any facility which employed vertical transmitting antennas. I`ve heard there are some verticals, but when serious investment is professionally made in shortwave transmitting antennas it is nearly always made in the horizontally polarized variety. Best regards, Richard Harrison, KB5WZI Medium and Long Wave, on the other hand... 73, Tom Donaly, KA6RUH |
Old Ed wrote:
So instead of a "T" between the trees where the top is a dipole and the vertical element is the feedline, why not a "T" between the trees where the top is a support rope and the vertical element is a monopole? Given that, I've gone to all the trouble of putting up a dipole. Why would I choose to put up something inferior to a dipole? Plus, with a vertical, I would have to lay in a ground plane only to make my noise level 2 S-units worse than with the dipole. Where's the ROI? Do you think a couple of trees 65+ feet away from said monopole would suck up all its radiated energy? And if so, why wouldn't they clobber the much closer, high-impedance ends of the dipole? Because the trees then act as part of the end-hat circuit which is a good thing. I never operate my antenna in a null. This is quite a remarkable feat! Do you only talk to a list of favored stations that are known to lie in your lobes? Yes, that's why I placed the lobes where they are. Or do you refuse to answer a list of stations that lie in your nulls? I don't QSO with weak signals. Life is too short for QRP. I also don't drive my pickup one mile per hour even if I only average driving it one hour per day. Seems by your logic, I should always walk since I can walk faster than the average speed of my pickup over any 24 hour period. :-) I'm afraid this analogy is so strained and inapplicable that it doesn't really need a response. It's the same logic. You are arguing that the average radiation pattern is what is important and not the directional gain while it is performing useful work. So to be consistent, you must also argue, that it is the average speed of my pickup that is important and not the speed while it is performing useful work. Since the average gain of a beam is about equal to a vertical, do you advocate getting rid of all the beams? :-) -- 73, Cecil, W5DXP |
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Where are my manners? I should have thanked you sooner, Danny.
THANKS! 73, Ed "Dan Richardson @mendolink.com" ChangeThisToCallSign wrote in message ... On Fri, 19 Mar 2004 00:06:28 GMT, "Old Ed" wrote: Hi Danny - Thank you very much for your contribution here! Any chance you could run another 360 azimuth cut at 26 degrees elevation? TNX es 73, Ed Sure Ed, however as you are comparing the dipole to a monopole I also modeled that. The monopole was resonated at 10.125 MHz. Using 16 ¼-wave in length buried 5" deep. The maximum elevation takeoff angle reported by EZNEC/pro using the NEC4 engine was 27º. Here are the results for average gain at 27º EL. Monopole -1.11 dBi Cecil's dipole 1.596 dBi 73 Danny |
Hi Richard -
Comments below... "Richard Harrison" wrote in message ... Old Ed wrote: "---trees could be used to support a monopole." Yes, but in supporting a monopole, the tree is more or less parallel, near, and lossy. Horizontal dipoles are somewhat perpendicular to trees which are likely to be in the nulls of the dipole pattern. The false assumption here is the qualifier "near." If you were worried about tree proximity, you could place the trees arbitrarily far from the monopole, by using the "T" support I described in my response to Cecil. As to the nice summary of ARRL handbook data that you provide in the following paragraphs, I am aware of it, and I do not take issue with it. My point in responding to Cecil was to introduce some OBJECTIVITY into the vertical/horizontal comparisons. I was NOT trying to convince anyone they should switch antennas, or that verticals solved all problems. 73, Ed Shortwaves are propagated effectively by bounce at the correct angle off the ionosphere. Propagation of shortwaves along the earth`s surface is seriously attenuated. Vertical antennas up to 5/8-wavelength launch their maximum signal along the earth`s surface, not good for skywave propagation in most cases. It works at sea where conductivity is excellent and over much greater distance than over land, so that not all shortwave tangential energy is necessarily wasted. Horizontal antennas produce no tangential aignal along highly conducting earth. The reflection at near zero elevation is equal and opposite in polarity and it cancels. High 1/2-wave dipoles (between 1/4-wave and 1/2-wave high) have gains at some angle between zero and 90-degrees as compared with the same dipole in free-space. A 1/2-wave dipole between 1/4-wave and 1/2-wave above good ground can have a dB or two gain at some elevation angle between 15 and 30-degrees. It`s not much, but it`s not a loss. Even over poor ground, the free-space 1/2-wave dipole characteristic is likely available at the useful elevation angle. I worked for years in shortwave broadcasting and have yet to see any facility which employed vertical transmitting antennas. I`ve heard there are some verticals, but when serious investment is professionally made in shortwave transmitting antennas it is nearly always made in the horizontally polarized variety. Best regards, Richard Harrison, KB5WZI |
This will be my last hurrah in this sub-thread, and
then I'll go into bandwidth conservation mode.... "Cecil Moore" wrote in message ... Old Ed wrote: So instead of a "T" between the trees where the top is a dipole and the vertical element is the feedline, why not a "T" between the trees where the top is a support rope and the vertical element is a monopole? Given that, I've gone to all the trouble of putting up a dipole. Why would I choose to put up something inferior to a dipole? Plus, with a vertical, I would have to lay in a ground plane only to make my noise level 2 S-units worse than with the dipole. Where's the ROI? I will interpret your subject change here as conceding the point I was trying to make. Do you think a couple of trees 65+ feet away from said monopole would suck up all its radiated energy? And if so, why wouldn't they clobber the much closer, high-impedance ends of the dipole? Because the trees then act as part of the end-hat circuit which is a good thing. This is somewhere between incoherent and grasping at straws, so again, I will consider the point made. I never operate my antenna in a null. This is quite a remarkable feat! Do you only talk to a list of favored stations that are known to lie in your lobes? Yes, that's why I placed the lobes where they are. Or do you refuse to answer a list of stations that lie in your nulls? I don't QSO with weak signals. Life is too short for QRP. Great, this is progress... we now know your ground rules! But I assume you will acknowledge that there are quite a few other amateur stations that want to be unrestricted in azimuth. I also don't drive my pickup one mile per hour even if I only average driving it one hour per day. Seems by your logic, I should always walk since I can walk faster than the average speed of my pickup over any 24 hour period. :-) I'm afraid this analogy is so strained and inapplicable that it doesn't really need a response. It's the same logic. You are arguing that the average radiation pattern is what is important and not the directional gain while it is performing useful work. So to be consistent, you must also argue, that it is the average speed of my pickup that is important and not the speed while it is performing useful work. Sorry, this didn't get any better. It's still nonsense, as an analogy. Since the average gain of a beam is about equal to a vertical, do you advocate getting rid of all the beams? :-) No, not all of them... only the ones that need to cover 360 degrees azimuth, and don't rotate. 8-) 73 es QRT, Ed -- 73, Cecil, W5DXP |
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