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amdx wrote:
Is it possible for a VSWR meter to read 1 to 1 with reactance at the antenna?... The vswr is determined by the absolute value of the reflection coefficient, being defined by: 1 + |ro| vswr = ---------- 1 - |ro| where the greek letter "ro" indicates the complex reflection coefficient Z - Zo ro = ---------- . Z + Zo So the one and only case in which we can have unity value for vswr is when |ro| = 0, or perfect match. In a * lossless * transmission line, the vswr is the same in every point of the line (this is an easily demonstrable general result, it comes right down from the above expression), so (with normal lines) the answer is definitely no ![]() Of course, as correctly pointed out by Cecil, in a lossy line the reflection coefficient decreases as you move along the line away from the termination, and the same happens to the vswr, so that a long lossy line may simulate a good matching also when the matching isn't even near to good (btw, using a lossy coax is an often used trick (especially in microwaves), when you need to give to the generator a seemingly good load). -- 73 es 51 de i3hev, op. mario Non è Radioamatore, se non gli fuma il saldatore! - Campagna 2006 "Il Radioamatore non è uno che ascolta la radio" it.hobby.radioamatori.moderato http://digilander.libero.it/hamweb http://digilander.libero.it/esperantovenezia |
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