Frank,
Comments interspersed with edited text
73, Gary
K9AY
------------------
> I have a 75x120 ft lot in suburbia and the backyard is full of maple
> trees. The only place I could install the antenna is in the SE corner
> between a couple of 30 -35 ft maples...
* There should be little, if any effect due to proximity of the trees. Also,
wire length and the exact shape of the loops are not critical -- yours
should be OK in that regard.
> The 52ft crankup tower that supports my coax Inv L is about 50 ft to the
> NW of the K9AY. A 80/40/30M half sloper on the tower generally slopes
> towars the K9AY. There is also an 80/40M dipole on the tower that runs
> generally NE/SW.
* Interaction is quite possible with tower/antennas at this distance.
> 1. The NE/SW loop does not seem to have much if any F/B on 160.
> 2. Listening on the BCB in 1500 - 1000 khz range there is significant F/B
> on the NW /SE loop. On the SE position NA broadcast stations literally
> dissappear. The NESW loop has some F/B but not at all as dramatic as the
> NW/SE.
> 3. Listening this a.m to W1 stations CQing on 160 the signals were same
> level on all positions except SE.
> 4. Copied FM5CD this am Q5 sigs ...no noise...on SW ... ..on other
> directions can still copy him but more noise.
* These all point to possible interaction with the tower and antennas, e.g.,
your best F/B is toward and away from the tower.
I's suggest evaluating it for a little longer. A high noise level and/or
poor conditions can make judgement of F/B more difficult -- but noise may
also be an indicator of coupling to other antennas. Daytime monitoring of
BCB stations is useful, since the noise is low and the signals are steady.
The observed F/B may be lower, since the arrival angle and azimuith may not
be aligned with the null, but you should get a feeling for the pattern.
Good luck!
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