Hi Steve,
Thank's for the QSO's on 160, especially on days when the band is about
dead. 1036Z and QSO's with ZL2REX (1015Z) and VK3ZL (0855Z and 1010Z).
Waiting for you, hi.
> With the small bandwidth available for CW DX operation on 160m, there
seems
> little to be gained in going to a folded antenna for gains in this area.
> However, the chance to get rid of some I2R losses and use a closed
circuit
> antenna, with the consequent reduction in general noise and static
build-up
> seem attractive.
I've heard the same claims Steve. Unfortunately they are folklore, with no
foundation of fact. Just like claims a coaxial dipole is quieter and has
greater efficiency, when in fact it has a bit more loss.
The folded dipole's loss resistance and bandwidth only changes by the
amount of loss resistance change if another parallel wire was added to a
regular dipole.
This antenna is covering in engineering text by Jasik in his Antenna
Engineering Handbook. Radiation resistance, by the IRE definition of
radiation resistance, remains exactly the same as a conventional dipole of
the same dimensions. The antenna receives the same and transmits the same,
and will hear the same noise. The closed DC loop in the folded dipole means
nothing for RF noises, unless your rig has no dc path from center conductor
to ground and the antenna is charging up and arcing periodically. If the
antenna shorted RF noise at the operating frequency, it would also short
the good signals out.
73 Tom
--
FAQ on WWW: http://www.contesting.com/topband.html
Submissions: topband@contesting.com
Administrative requests: topband-REQUEST@contesting.com
Problems: owner-topband@contesting.com
|