CompuServe Messages

Physics was not, to put it mildly, my strong subject. When you get into the world of wave propagation, a lot of phenomena are wierd to outright bizarre. As I understand it, the signal won't propagate and won't "bounce" if all the dimensions of the "waveguide" aren't large enough to allow its passage. I seem to recall a device in a ham radio magazine 3 decades or so ago that used a small cavity to build a variable attenuator (i.e an "RF Volume Control"). There was a transmitting antenna at one end and it worked by moving a receiving antenna up the cavity. The attenuation per inch of cavity was specatacular.