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#14
April 26th 05, 03:19 PM
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"Ian White GM3SEK" wrote in message ... wrote: Rather than deflect away from Reg's needs may I go back to the "compared to a dipole" statement which Richard keeps brushing off. If the gains are different then the angle for max radiation is different and if you do not take this into account by searching for the individual point of maximum gain position then the the measurements are in total error. To put antennas at the same height and then measuring at the same stationary point for receive, switching back and forth is not a true comparison because of the different elevation angles. I don't think Richard is attempting to deny that. The question is about lab techniques and error measurement and Richards post was in answer to that. Another person insinuated that a person who tests against a dipole and measures after a skip has taken place is in Lu Lu land because he assumed he was literally describing a normal lab test of comparing to a dipole! Remember, Richard was replying to the initial post which was very specific in nature regarding lab testing and degree of error ! Assumption has no part in a real laboratory. His tests were not intended to measure the gain of the antenna. They were intended to answer a much more practical question: "How much stronger is the signal from the curtain array, as delivered into the BC target area, compared with using a dipole?" That's what the station owners wanted to know, and they specifically wanted that answer to include all the variables of antenna patterns and ionospheric propagation. I could not agree more and stated so in my last post As you have correctly pointed out, in any environment except free space, that number is not the same as the antenna gain in dBd. Anybody who has thought about it is aware of the problem, and that clearly includes Richard. Then why is he introducing dbi into the subject using Kraus as a backup? Why does he state that TOA are "usually" the same when the opposite is true especially when comparing a curtain to a dipole ? I don't believe that to be correct In the absence of denial by a guru must I assume he is correct or he meant something else and everybody knows what he said is true? So you agree with the poster who stated that if a person thought that a dipole comparison test consistes of comparing after skip took place, is in Lu Lu land? Everybody agrees with you, so you can stop banging on that open door. They do ....???? And the question regarding propagation and antenna function can we assume he is correct on that also ? I don't like to "assume" that he meant something different and let the newbies as well as I to be lead astray. Must I assume he is correct in that last sentence he made where I am asking for a corroborating technical written statement ? Richards last statment was /is an echo of a similar posting made a few months ago and the Gurus said nothing to confirm or deny it's voracity?. What are we meant to assume , that if a guru doesn't question it it must be correct? I personally would rather see corrobaration in a accepted technical writing than set up the beginnings of an old wives tale The old saying is still true , don't rely on one gurus answer, ask another and then another and ensure that context is correct. I await Richards response with interest so that I may read an authoritive statement for myself without the need for "assumption" as to what he "really" meant to say but didn't. If you know what he "meant" to say on that last remaining subject why not supply a helping hand ? Art -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
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