|Subject:||Re: [TowerTalk] URI magic antennas|
|From:||Jim Lux <firstname.lastname@example.org>|
|Date:||Tue, 08 Jun 2004 09:57:19 -0700|
At 08:59 AM 6/8/2004 -0700, you wrote:|
reducing the loss in the coil will make the bandwidth narrower. You run into this when you contemplate making high efficiency compact loops. Sure, I can get the efficiency up real high with a suitable design on a 1m diameter loop on 80m, but it will have to be on 80m, and real slow CW, because the bandwidth starts getting down to the 10's of Hz range (at least you won't have key clicks!)What about supeconducting loading coils and/or elements? One could generate VERY high currents with low losses (unless you count the energy requirement of keeping an RF-transparent thermos of liquid helium full.) Just the sort of thing a University Physics lab could do.
There's a whole literature (Harrington and Chu is the usual reference) on fundamental limits of bandwidth, physical size, etc. for resonant antennas.
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.
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