[BC] Re: Directional FM Antenna measurements...

[Mark Humphrey]

I once came across a license application filed in the early '80s to
cover a NCE-FM construction permit that required about 6 dB of
suppression in one direction.  This station had originally been
constructed as a non-directional 3 kW Class A near the low end of the
band, but was asked to move to a higher frequency to reduce TV 6
interference.   The shift was 1.6 MHz (eight channels) so it was not a
minor change.   The proposal had some overlap with a first-adjacent
station's application to increase power and was flagged by the FCC as
MX-ed, so a deal was negotiated between licensees requiring each to
pull back their contours from one another.

The Class A hired a PE to sign a statement that the original antenna
had been retuned and "directionalized" by mounting it on a triangular
frame of steel members resembling a wider tower section (no further
details) and he included two hand-drawn polar plots showing a very
nice symmetrical 6 dB reduction across the required arc and a
tabulation of this pattern in 10 degree increments.   There was no
evidence that the antenna manufacturer had done a range test or even
knew about this modification.  Surprisingly, rhe FCC accepted the PE's
exhibit and granted the license, however CDBS has never shown the
station as directional.

Note that this application was filed over 25 years ago and does NOT
reflect current FCC policy, but it goes to show what slips by from
time to time.

Mark

>>    So, here's my question-has anyone on this list ever done their own
>> antenna measurements on an FM DA, submitted them to the Commission and
>> received the FCC's blessing?
>>
>