[TowerTalk] Horizontal Stacking of HF antennas

[Dennis Egan]

I now have two 15-4CD 4 el 15m monobanders available for setup in a Field
Day Style operation.  Unless I can find someone in the NE that is willing to
loan or rent me a trailer mounted 40-50 ft crankup tower, vertical stacking
is out of the question- but horizontal stacking would be possible.

The problem I am having is that I can find little or no information on
horizontal stacking of HF beams.  My experience tells me that:
1. If the two antennas are fed in phase with the centers spaced (???) apart,
and they are both beamed in the same direction, the main lobe should be 3db
louder than one antenna by itself.
2. If the beams are fed in phase and beamed in different directions, each
main lobe would be 3db down from feeding just one antenna, but there would
be two gain peaks in the direction of each antenna.
3. By slightly offsetting the beam path of each antenna, it would probably
be possible to cover over 90deg in any direction with a signal louder than
either beam by itself.

Some of the lingering questions I still have go to the spacing- how far?
What effect does it have?  Is it worthwhile to build a phasing box to adjust
the phase of the feedpoint?  What do I get for the time and effort?  Any one
done any modeling on this?

Any help is appreciated.

Dennis NB1B



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