[UK-CONTEST] Feeding your dipole

[peter jackson]

The correct way to feed your dipole is to use 75 ohm balanced twin feeder,
that's the feeder that looks like twin flat cable. This is because a dipole
is a balanced antenna. A balanced to unbalanced balun 1:1 is placed at the
TX. There are advantages to this, the feeder is very light weight so the
dipole is not pulled down in the middle. RF is pickup from the antenna by
both feeder conductors therefore cancelling out and not re-radiating. When
using coax, which is unbalanced, RF is picked up on the outer conductor
which radiates  sometimes causing TVI and distorting the radiation pattern.
That's why a balun is used by some at the antenna feed point. But they are
fairly heavy, any V shaped dipole (not inverted V) radiates poorly. This was
demonstrated very effectively some years ago at the HF Convention.
   I used balanced twin feeder for many years, but unfortunately after
several years the wire in the feeder breaks due to it wafting about in the
wind.
    I must say that these days I do use coax without a balun and so far I
haven't had any problems with RF in the shack or TVI. Maybe it's because a
lot of the feeder run is underground.
73 Pete G3KNU