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## Re: [TowerTalk] Takeoff Angles and Non-Reciprocal Propagation

 To: "Richard (Rick) Karlquist" Re: [TowerTalk] Takeoff Angles and Non-Reciprocal Propagation Jim Lux Fri, 02 Nov 2007 20:06:16 -0700
 ```>> >> It seems to me that a good portion of Station B's signal arriving at the >> hill could overshoot Station A because it wasn't diffracted enough. The >> path taken by the signal from B to A would be identical to the path >> taken by the signal from A to B EXCEPT for the portion between Station A >> and the hill. Think directional coupler. >> Uhh, nope.. even though it sort of seems that way at first glance.. Imagine that the top of the hill is a big lens or prism that bends the ray (which is what diffraction is, in one sense).. Launch a ray from A towards B and it follows a certain path, apparently bending over the top of the ridge. Some distance after the hill, stop the ray and send it back exactly as it came. When it gets to the prism/lens it will bend it just like it did on the outbound trip and wind up at A. As long as there no nonlinearity in the system, it works. Where there IS non-reciprocal propagation you need something else. here are some examples: a) propagation through the ionosphere, which is anisotropic. The polarization is rotated by the Faraday effect, but the same rotation regardless of direction, so, if you have polarized transmit and receive antennas, oriented, say, 45 degrees apart, and the rotation is 45 degrees, A signal from A to B winds up perfectly lined up, but a signal from B to A is cross polarized. b) the ordinary and extraordinary ray (polarization dependent) follow different paths, so when they combine the net effect is different depending on the direction (actually another case of the phenomenon in A) c) sound propagating in a medium with a velocity gradient. This causes sound to bend down when going downwind, and bend up when going upwind. d) various and sundry light propagation through various crystal phenomena (e.g. polarizers, birefringent materials, etc.) _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk ```
 Current Thread [TowerTalk] Takeoff Angles and Non-Reciprocal Propagation, David Gilbert Re: [TowerTalk] Takeoff Angles and Non-Reciprocal Propagation, Terry Conboy Re: [TowerTalk] Takeoff Angles and Non-Reciprocal Propagation, Richard (Rick) Karlquist Re: [TowerTalk] Takeoff Angles and Non-Reciprocal Propagation, David Gilbert Re: [TowerTalk] Takeoff Angles and Non-Reciprocal Propagation, Richard (Rick) Karlquist Re: [TowerTalk] Takeoff Angles and Non-Reciprocal Propagation, David Gilbert Re: [TowerTalk] Takeoff Angles and Non-Reciprocal Propagation, Richard (Rick) Karlquist Re: [TowerTalk] Takeoff Angles and Non-Reciprocal Propagation, David Gilbert Re: [TowerTalk] Takeoff Angles and Non-Reciprocal Propagation, Richard (Rick) Karlquist Re: [TowerTalk] Takeoff Angles and Non-Reciprocal Propagation, Jim Lux <= Re: [TowerTalk] Takeoff Angles and Non-Reciprocal Propagation, Roger (K8RI) Re: [TowerTalk] Takeoff Angles and Non-Reciprocal Propagation, Jim Lux Re: [TowerTalk] Takeoff Angles and Non-Reciprocal Propagation, David Gilbert Re: [TowerTalk] Takeoff Angles and Non-Reciprocal Propagation, Michael Keane K1MK Re: [TowerTalk] Takeoff Angles and Non-Reciprocal Propagation, David Gilbert Re: [TowerTalk] Takeoff Angles and Non-Reciprocal Propagation, Michael Keane K1MK Re: [TowerTalk] Takeoff Angles and Non-Reciprocal Propagation, David Gilbert Re: [TowerTalk] Takeoff Angles and Non-Reciprocal Propagation, K4SAV Re: [TowerTalk] Takeoff Angles and Non-Reciprocal Propagation, David Gilbert Re: [TowerTalk] Takeoff Angles and Non-Reciprocal Propagation, Dan Zimmerman N3OX