Fellow Topbanders,
Summertime is in-field time.
For give me for taking space on a lowband antenna subject but have tried to get
advice on the antenna reflector with no reply !!! :)
Been bogling my mind for some time on the best 160 / 80 array for this location
(physical restraints). The W0UN 9 el circular array for 80 M has had my
interest and is still not ruled out (ON4UN Low band Dxing)
At first I plan to do the following and would like some advice.
I am going to put up a 110 ft. free standing tower this autumn and would like
to apply 4 el. phased arrays for 80 & 160, supported by caternary ropes from
the top of the tower.
My idea goes like this:
3/8 wl. vertical for 80 M spaced 1/4 wl. with ground mounted radials
1/4 wl. vertical for 160 M spaced 1/8 wl. (Same radial system and radiating
wire as for the 80 M) utilising the 80 3/8 wl. as the vertical part off the
antenna and a topload sloping wire (as part of the caternary).
Between the top load and the vertical wire will be installed a trap (either
coaxtrap or L/C). Limited bandpass on 160 is acceptable.
This configuration has the following advantage:
1. Utilise same ground mounted radial system
2. One central support
3. 3/8 wl. on 80 M increase the single vertical wire resistive radiation (from
about 36 to 50 ohm) which would lower possible ground losses as current max is
higher above ground.
Disadvantages ?
Any thoughts very welcome !!
With regard to feed system I anticipate to go by practical real life
measurements.
80 M, standard quadrature 90 degree phasing, Christman or Lewallen.
160 M, 135 degree phasing, modified Lewallen.
I am not a modelling expert but would be grateful if someone could look at this
array in EZNEC for me.
Thank you in advance,
Henrik - OZ1ING
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