In message , Harry H
writes
I am wondering if its possible to build a 6 element "round" quad antenna,
that is the elements are circular instead of square.
I want to use it for DFing and have the centre frequency of 438 mhz.
I will be mounting the elements on an insulator above the boom, will the
boom have to be non conductive?
I intend to use 1/8" alloy wire for rigidity, and make the element mounts
out of insulating material so they can be slid along the boom, will the
frequency to wire diameter ratio have any effect on the length of each
element?
Here's a pair of 27 Quad -loops I built for contesting. They were scaled
from the G3JVL 23cm design. They worked really well. Gain of each is
19dBi measured on sun-noise.
Http://www.b-howie.demon.co.uk/70cm%20ant.jpg.
An antenna programme like MMANA will handle Octagonal loops ( which is
close enough) if you want to optimise before building. I've got an MMANA
model for the 27ele , however the antennas are constructed out of strip
elements, so I had to guess it a bit.
The boom can be conductive as long as the insulation is at least half
the boom diameter. Mine are bolted to the boom ; it's a low voltage
point. Driven element is copper strip fed by flexi-rigid cable at the
top and fed through the bottom on a bush. Matching is done by making
the DE slightly oval by squashing it then soldering the flexi-rigid at
the boom
Brian GM4DIJ
--
Brian Howie