Dave Platt wrote:
I believe that the high (4.1 dB) figure you are quoting is for an
end-fire array, with the two antennas being fed 180 degrees out of
phase.

Actually 135 degree phasing and a cardioid pattern.
180 degree phasing results in a figure-8 pattern with
3.3 dB gain.

Was out of town during the holidays and didn't realize
that the earlier statement was limited to a side-by-side
configuration.

In a truck-antenna situation this would require placing the antennas
in a front/back arrangement, not side-to-side.

Yes, but what better place than the top of a metal
trailer? Years ago, I helped a CB friend in AZ install
one on his motor home with about 5 foot spacing if I
remember correctly. Measured front to side ratio was
huge.
--
73, Cecil http://www.w5dxp.com