Antenna
of the month V
April 2003
The
Delta loop for 20 metres.
The
gain of this antenna should be about 1dB over a dipole or about 1.26 times.
The
delta loop.
You
require 72 feet of either copper wire or stranded pvc-covered wire.
2
small insulators and one triangular shaped piece of Perspex about 3"
long on each side. (This is to provide a feed point for the antenna).
One
piece of 75 ohm coaxial cable 11ft 6 ins long.
1
PL59 plug.
Divide
the 72 ft length in to 3 equal lengths of 24 feet, Lay out in a
triangular
shape on the lawn, check each side carefully to get a good
triangular
shape. Put an insulator at
each corner of the base of the triangle.
Fix
your triangular feed insulator at the apex of the triangle and adjust the length
of each side so that it is 23ft 8 ins long and secure the apex ends of the wire
firmly on your triangular insulator. Total length is now 71ft.
Take
the length of 75ohm coax and make one end with a tail from the braid and join
the centre to one side of the apex point and the tail to the other side. Fit a
Pl59 plug on the other end.
This
antenna can be erected either as a conventional Delta (triangle) or inverted,as
below.
For DX operations I would recommend using it inverted.
For this you will require two masts.
This antenna like all antennae will work best by being as high as
possible above ground, however I use one with the apex inverted and only 8 ft
Above
ground and get excellent results.
With thanks to John D Heys G3BDQ and Practical Wire Antennas also
Practical Wireless Data sheet May 1996.
