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Re: [IRCA] [NRC-AM] DKAZ Antenna
So is the minima actually moving or is the rear-response beamwidth changing?
Or is that the same thing? And Nick: (especially in your 1640/1680
example), might there be some skywave in the mix? Makes an Old Novice
wonder...
KAZ YOUR THOUGHTS ??? ALSO...SEE LAST PARAGRAPH BELOW
Mark Durenberger, in search of better understanding
-----Original Message----- From: Nick Hall-Patch
NICK 1: I haven't had experience with two D-Kaz Mark, but do I gather then
that you haven't seen evidence of null steering with the DKaz alone? MARK
1: I HAVEN'T SEEN EVIDENCE OF STEERING, JUST DEPTH ADJUSTMENT (PRESUMABLY
INCLUDING RE-SHAPING OF SIDE-LOBES). MARK 2: AND I COULD BE WRONG ABOUT
THIS.
NICK 2: I'm not sure my use of "null steering" is entirely the correct
term, even for the Flag. The direction for minimum signal response moves
with adjustment of the termination (especially for vertical polarization),
but the depth of the null is not ( ) as great as the best null obtained
directly off the back of the antenna. MARK 2: NICK, I'M NOT CERTAIN THIS
IS PROVED. DATA! MORE DATA!!!
NICK 1: I had observed similar (and <900 ohms) termination values for
Portland on 1190 and Seattle on 1000, one 50 degrees off the back of the
antenna, one 30 degrees, but realize that although Portland on 620 and and
Seattle on 710 also had similar values of termination, that value was
higher. And to throw it all out, Portland area on1640 and Seattle on
different values of termination altogether.
NICK 1: Now I think of it however, doesn't the fact that 1640 and 1680 had
different termination resistances for best nulls show a type of "null
steering" (or ?). In both cases, the null was around -25dB, and the
difference in termination resistance was a couple of hundred ohms. MARK
2: WOW THAT'S A LOT OF CHANGE.
. NICK 1: I had no reference right off the back of the antenna at those
frequencies, but I assume that both values of termination resistance
couldn't have each been appropriate for the deepest null off the back of the
antenna.
MARK 2: I MAY HAVE A LOT OF FIELD TIME NEXT WEEK AND CAN TAKE MEASUREMENTS
FROM 280 DEGREES AND FROM 325 DEGREES. CAN YOU SUGGEST A SERIES OF
MEASUREMENTS THAT MIGHT MOVE OUR DISCUSSION FORWARD?DX
best wishes,
Nick
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