Dear all,
I have encountered something what appears to be a bug in Antenna Optimizer
v6.5.
Modelling a 70cm colineair antenna with stub and gamma match yielded
contradictory results in the 2D and 3D radiation patterns and gain.

I have included the 70COLIN.ANT file below for those who want to experiment
with it.

You will see that the 3D radiation pattern reports 4.99dBi gain. The 0°
elevation azimuth-plot yields an almost uniform gain pattern of 4.01dBi.
This is still ok, because the higher gain direction can be at a higher
elevation. The 0° azimuth elevation-plot is also still ok.

Plotting a 90° or 270° azimuth elevation-plots is what really produces the
most akward results with an asymmetrical end-fire pattern and a gain of
5.25dBi, not observed in the 3D-plot, nor the azimuth pattern.

Could it be that AO is assuming a symmetry that is not there?
Is this bug/problem known and has it been reported yet?

I tried to contact the author of this sofware, Bryan Beezley on
but unfortunately this email address does not seem to be active anymore. Has
anybody Bryan's new email address?

70cm Colinear
Free Space
434.971 MHz

8 copper wires, mm
wdiam = 12 ; antenna wire diameter
fdiam = 12 ; feeder diameter
elem = 338.1602 ; element length
stub = 142.5328 ; stub length
hshort = 30 ; half the short length

elstop = hshort + elem

1 0 0 -elstop 0 0 -hshort wdiam ; lower element
1 0 -stub -hshort 0 0 -hshort wdiam ; lower stub part
1 0 -stub -hshort 0 -stub 0 wdiam ; lower short half

1 0 -stub 0 0 -stub hshort wdiam ; upper short half
1 0 -stub hshort 0 0 hshort wdiam ; upper stub part
1 0 0 hshort 0 0 elstop wdiam ; upper element

1 0 -stub 0 0 0 0 fdiam ; feeder
1 0 0 -hshort 0 0 0 wdiam ; gamma

1 source
Wire 7, End1

--


PS: Please, send your comments to the newsgroup. As of tomorrow I will be on
a business trip for the next two weeks and will only be able to respond
occasionally. Hopefully, by the time I am back you guys have found / fought
it out all ;-)

73 de Serge ON4BAA - HB9DWU

propagation & ham info at:
http://salsawaves.com/propagation/