[TenTec] W5GI 'mystery' antenna analyzed

[Stuart Rohre]

The W5GI antenna is a stub decoupled doublet (dipole).  It is designed to be
gain antenna on 20m as is the G5RV and present a tunable load on other
bands.

For detailed analysis, see the Gene Hinkle K5PA Power Point on the web
(Google for : "Gene Hinkle, K5PA Antennas"
; that he presented in an antenna forum of Austin Summerfest Ham Radio
Convention, Aug. 2004.  The antenna has a stub of coax on each side to
decouple the outer part of the antenna from the inner dipole.  Instead of
having the stubs hang vertically, W5GI incorporated them into the doublet
length.  This was written up in CQ in 2003 or early 2004 as a "mystery
antenna" because he got conflicting antenna analysis program results from
his friends.  As K5PA points out, you have to analyze the elements
conventionally in one of the finite element analysis programs like NEC, then
consider the stubs as lumped decouplers, and as antenna element extensions
since they are in line with the wires on each side.  Note, the way the stubs
are connected is not the same as the "Bazooka" antenna which is a coax
antenna of greater diameter to broadband the dipole it forms.

-Stuart
K5KVH