"Randy Yates" wrote in message
...
Hi Folks,

This is my first post to this group. I'm a EE, so I've
had all the theory - now I want to know how these things
work.

Basically, my question is this: how can a a TV antanna
cover, what, 60 MHz to 800 MHz? That's over three octaves,
and if the antenna elements are designed to be a fixed
portion of a wavelength, why does this work over such a
large range?
--
% Randy Yates % "So now it's getting late,
%% Fuquay-Varina, NC % and those who hesitate
%%% 919-577-9882 % got no one..."
%%%% % 'Waterfall', *Face The Music*, ELO
http://www.digitalsignallabs.com

Hi Randy

You have probably thought about Log Periodic Antennas. They work by
forcing a null in the direction away from their feed point. The "dipoles"
that most nearly match the line connecting them will be the most active of
all. The active dipoles will be near 1/2 wave long. Each succeeding
dipole is fed 180 degrees from the dipoles on either side.
When the frequency is trippled, the dipole patern changes such that the
lobes add in a way favorable to the desired pattern if the dipoles are bent
to make the Log Periodic Vee Antenna.
There is a 3 to 1 relation inherant in the LPV that coincides with the
near 3 to 1 spread in assigned TV channels.

Jerry KD6JDJ