The G3TXQ Broadband Innovation
In the autumn of
2007 G3TXQ (Steve Hunt) conducted reflector experiments in an attempt to broad-band the hexbeam. An exciting hybrid scheme emerged which modeled and tested very well. The driven elements were kept in the classic "W" or "M" shape. However, the reflector was run around the fiberglass support structure to form a large "C" or "U". This keeps the reflector as far away from the center post as possible. It also makes the antenna about 15% bigger than the classic HexBeam.
G3TXQ Hex Beam Geometry
When incorporated into a 5-Band array, this geometry produces F/B > 10dB and SWR < 2:1 across all of the 20m, 17m, 15m and 12m bands, and approximately 1 MHz of 10m. That is a fairly dramatic improvement over the classic Hexbeam. This design caught my attention, but I wasn't sure I knew how to actually build the antenna.
Working closely with G3TXQ, K4KIO (Leo Shoemaker) made his own G3TXQ Hex and provided detailed
on his site to help those interested in home brewing the new design
affordably. (Update: QST published this design in March 2009 and
K4KIO now offers a commercial
Broadband Hex Beam kit.)
K4KIO QST Article
Making and Assembling the G3TXQ Hex Beam
With K4KIO's fully illustrated pages, I had a
virtual Complete Idiot's Guide to
building the antenna, and no more excuses for not getting started. I
began buying and ordering stuff using Leo's
Parts-needed list, which even tells you which vendors carry the products. Fiberglass tubes for the spreaders and center post were ordered from Max-Gain Systems. I fabricated my own base plate per Leo's plans, which was a little intimidating for a guy who is more comfortable with a keyboard or a soldering iron than a reciprocating saw. But in the end, it was no problem,
even for me. The majority of the work was done at a leisurely pace, indoors, during the winter months.
Assembly was not difficult when the warm weather arrived
(see construction & assembly photos below). Once assembled, no tuning was required as the SWR looked good on all bands with the base at only 4 feet. The antenna is a near perfect match to 50 ohm coax on all bands. I now have the base at
50 feet on an AB-577 surplus military mast (see comments on the mast below). This height is a good compromise for signals arriving at various angles (See Hex Beam Height arrival angle studies by G3TXQ).
Performance has been simply outstanding. I know what to expect from a directive array as I have owned and used 3 element trapped triband yagi antennas before.
To say that this beam performs beyond my expectations, would be an understatement.