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 DPRG: Ming Modules?!@\$#@@! Message index sorted by: [ date ] [ thread ] [ subject ] [ author ] Previous message: DPRG: Intersil PWM chip (CDP68HC68W1) Next message: DPRG: ANother Sumo match Subject: DPRG: Ming Modules?!@\$#@@! From: Robert L. Jordan rljordan at airmail.net Date: Mon Nov 8 18:12:44 CST 1999 ```Thanks Doug. I like Math when it is in English!-) Robert Jordan Douglas Kilgore wrote: > The formula given in the ARRL Handbook for calculating antenna length: > > 1/4 wave: > 234/Mhz = Length in Feet > > Therefore > 234/310 = .755 ft = 9.06 inches > That length should be attached on one end only ie; an end fed antenna. > > Doug > > MIKE MCCARTY -- 93789 wrote: > > > )I am probably wrong here, but I thought that only worked > > )in a vacuum and that for air, the number was significantly > > )different. (something like 10% different??????????) > > > > In normal air, the difference is completely negligible. Up in the > > ionosphere, it is a different matter, which is what allows us to listen > > to radio broadcasts from far away. > > > > The issue with propagation speed has to do with the speed of propagation > > in the *conductor* which makes up the antenna, and may be as low as 75% > > of c or so. > > > > )Using Ming's numbers: 9.08 * 4 = 36.24 inches = 0.9205 meters > > > > 1 yard = 0.9144 meters. > > > > )OOPS! I just noticed that's for 310 MHz (not 300). > > )0.9205 * 310 / 300 = 0.9512 meters for 300Mhz > > > > 1 meter is not 36.24 inches. 1m = 39.37 inches (closely enough). That > > gives > > > > (310/300)*39.37 = 40.68 inches > > > > )Either way, if you believe Ming, it appears to me that > > )the 3x10^8 m/s doesn't work for air. > > > > It's not the air that matters, really. > > > > But I haven't measured the speed of propagation in the telephone wire I > > used for the antenna to within 10% anyway. > > > > Mike > > ---- > > char *p="char *p=%c%s%c;main(){printf(p,34,p,34);}";main(){printf(p,34,p,34);} > > I do not speak for Alcatel. <- They make me say that. > > This message made from 100% recycled bits. ------------------------------ ``` Previous message: DPRG: Intersil PWM chip (CDP68HC68W1) Next message: DPRG: ANother Sumo match Message index sorted by: [ date ] [ thread ] [ subject ] [ author ] More information about the DPRG mailing list