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## Re: [TowerTalk] Measuring radiation resistance of a vertical

 To: "Rick Stoneking" ,"TowerTalk Reflector" Re: [TowerTalk] Measuring radiation resistance of a vertical "Tom Rauch" Tom Rauch Tue, 2 Nov 2004 09:39:38 -0500
 ```> Is it possible to measure the radiation resistance (only) of a vertical with > either an antenna analyzer or some other type of readily available piece of > equipement? Yes it is, but you probably cannot do it. To measure radiation resistance you either have to know the effective current causing radiation and the net power radiated or you have to measure the impedance at a point in the system and then shield the antenna in a large lossless dome and observe the change in resistance when the shield is in place. The converse of this is how do I measure the loss resistance of > the antenna? I am trying to determine how effective my radial system is and > how efficient my antenna is. http://www.w8ji.com/radiation_resistance.htm The best way to measure anything is to measure what you want to know as directly as possible. Radiation resistance will NOT tell you efficiency unless you somehow can manage to normalize all losses to the point where radiation resistance is defined. The only way to measure efficiency is to measure applied power and net radiated field. That's pretty difficult. The most effective thing you can do is to establish a good reference antenna and compare the two. Most people can't do that. What I would suggest is you change the ground system by pulling in many extra temporary radials while measuring FS at a distance without disturbing anything else. If you see a FS change, you know your system needs work. One error people make is they measure at too large a distance. 2 to 5 wavelengths is far enough. 73 Tom _______________________________________________ See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA. _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk ```
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