[TowerTalk] 160-m Inverted L or Sloper?
ad4hk2004 at yahoo.com
Tue Nov 15 10:50:22 EST 2005
I have more space than most for antennas.. I am tinkering with 80 meter vertical arrays right now... My reference antenna, a quarter wave vertical, is 600+ feet out front of the nearest array, and Eznec still shows significant interaction with a change of >3dB in the FB ratio and distortion of the forward pattern... Nothing that I am likely to hear on the air, but it is there... I am adding a relay to open the reference vertical when using the south firing array...
Interestingly, the two directional vertical arrays are mounted 250 feet apart (~1 wl) with the reflectors facing each other.. Eznec shows minimal interaction with only 0.02 amps of induced current in the' idling array' (worst case) for 1 amp in the active array and minimal pattern changes, not enough to make me install relays...
So, other antennas in the near (and not so near) field can have significant effects on the expected pattern... When I move the reference antenna towards the driven array (via Eznec) the interaction goes up exponentially and at a quarter wave of spacing the directional array pattern has become garbage...
denny - k8do
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