that is what i said, but in regards to 'shorten the length' of the 80m part
it is a loading coil he needs.

"Ham op" wrote in message
...
He wants multi band operation. Therefore he needs traps to provide the
necessary isolation for 40 and 20 meters.

Dave wrote:

for an 80-40-20 dipole you don't need 'traps' to shorten the 80m piece
you need 'loading coils'. 'traps' have a resonance that effectively cuts
off the section of the wire past them making the inner part resonant on
the higher frequency, so you need 'traps' for 20m and 40m. 'loading
coils' are simply an inductance that makes the section appear longer than
it physically is.

"Vinnie S." wrote in message
...

I want to construct a 80-40-20 meter dipole, but want to trap the 80
meters to
shorten the length. Does anyone know where I can get good quality traps?
I am a
beginner as far as antenna theory.

Vinnie S.

On Sun, 4 Sep 2005 12:18:40 -0000, "Dave" wrote:

that is what i said, but in regards to 'shorten the length' of the 80m part
it is a loading coil he needs.

The traps -do- shorten the overall length of the antenna. Because the
80-meter part -is- the total length, I would say the traps shorten it.
In other words, below their resonant frequency they are inductive and
function as loading coils.