TopBand: Four-square antennas/ interaction effects

[John Mitchell]

In brainstorming some new antennas, an issue arises.  With a four square
made up of 4 inverted L's, suspended from orthogonal catenaries off a tower,
what effect, if any will the central supporting tower have upon the phasing
and subsequent pattern of the four-square?  

Specifically, the tower will be around 1/4 L for 160M, and proper spacing
for each
of the vertical antennas would result in the tower being in the middle of
the antenna
array, spaced 1/8 L from each vertical, as depicted below.
        
                        ANT
                           

        ANT         TWR          ANT


                        ANT

Using something like a Comtek Hybrid Coupler (ACB-4) to phase the verticals,
the concern is that the center support, located 1/8 wave from and directly
in-line with
the verticals, would interfere with the phasing network.  Has anyone tried
phasing
inverted L's like this, and did the tower affect the phasing?  The verticals
would
each be about 80-90 feet vertical, with each of the "tails" pointing in
toward the
tower.

A secondary question arises regarding the planned use of elevated feedpoints and
radial systems.  How does one best handle the intersecting !/4 L radials,
assuming four or so on each antenna?  Would it be best to connect them or
overlap them?

Any input would be appreciated, especially that based on actual experience.  
To conserve reflector bandwidth, please email me, and I will summarize
replies if there is general interest.

Thanks,
73,
John K4IQ
        


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