When I started using 2m for activating SOTA summits, I
found getting contacts difficult using just the short flexible whip “Rubber
Duck” antenna. So I was on the lookout for a simple gain antenna suitable for
portable use.
I used a design
based on an article in the ARRL handbook 1998/9. I use a plumbers overflow
pipe which comes in 21.5mm X 2m from a local DIY store (B & Q) for the
boom.
For the elements, I
used three 6mm X 1m hollow aluminium rods also from the same store.
The reflector should be 40" - you
can add a stub of aluminium rod to make this length up if you wish, I just
ignored it, and left it at the 1m length as it came.
Connect coax directly to end of driven elements. I
used a small bolt through the end and attached short insulated wires to the
bolt. At the other ends I attached spade connectors to enable quick and
easy connection to coax. Keep the wires short, otherwise this could affect
the SWR. Banana plugs can be used to connect the wire as these fit the
aluminium rods perfectly.
18.2" from the reflector, I attached an "omega" shaped
plastic pipe holder designed for this pipe to allow a fishing rod (G3CWI's
ideal) or pole to go through this holder to support the yagi.
Placed over the top of the fishing
rod, it comes to rest conveniently three quarters of the way up below the apex
of my dipole. I use vertical polarisation, as most contacts I make are on
2m FM.
Using the antenna
vertically only allows only one stopper or connection of the elements to hold
the element halfway through the boom without the need to fix both sides. I
use a cable tack with the nail removed, which happens to be 6mm and snaps onto
the element, which I then glue and secure with a piece of electrical tape. For
the + side of the driven element I just clip on one and temporarily hold in
place with tape again.
The
completed yagi weighs only about ˝ pound, the elements can be packed inside the
boom which can then fit into a rucksack or attached to the outside.
Hope this works as well for you as
it does for me. Please Email for further info if required. Struggling
to make the 4 QSO’s will be a thing of the past, but don't quote me on that
hi!!
Roger Dallimore
MW0IDX K3IDX February
2003




