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## Re: [TowerTalk] Understanding Antenna Impedance Measurements (wasFoam ca

 To: Jan Erik Holm Re: [TowerTalk] Understanding Antenna Impedance Measurements (wasFoam cables and velocty factor) Jim Lux Tue, 15 Nov 2005 14:27:19 -0800
 ```At 11:49 PM 11/14/2005, Jan Erik Holm wrote: >Jim Brown wrote: > > > Also, I wouldn't trust that your guess about the > > electrical wavelength in coax to tell you for certain what the > > antenna Z is. But the Z reading combined with the VSWR will help. > > > > Jim > > > > > > >How do you mean now? >At multipels 1/2 wl electrical transmission line length the >load Z will be seen at the other end, i e it will be transparent. But the line's only 1/2 wl at one frequency.. at lower frequencies, it's less than 1/2wl and at higher, it's more. Given the electrical length of the line (at some one frequency), though, you can figure out what the electrical length is at other frequencies, and then apply the transmission line formulas to see what you get. This is essentially what the port calibration of a network analyzer does. Jim, W6RMK _______________________________________________ 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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