For anyone who wonders, the 180 degree phasing was chosen because it
was dead easy to implement, was not fussy with respect to matching,
and gave the highest RDF at the expense of a little F/B.
Simply ... the 180 degree phasing cancelled the high angle response
from the "loops" (the horizontal component of the bottom wires and
the sloping sides). Think about it!
73,
... Joe, W4TV
On 2/15/2013 7:55 AM, Pete Smith N4ZR wrote:
For whatever it is worth, afew years ago I put up an endfire array of
two K9AYs spaced 135 feet, phased 180 degrees. It worked probably the
best of any receiving antenna I have had here on 160M. Modeling with
NEC2 showed an excellent RDF - whether that was achieved in real life
only God knows.
For anyone who wonders, the 180 degree phasing was chosen because it was
dead easy to implement, was not fussy with respect to matching, and gave
the highest RDF at the expense of a little F/B.
73, Pete N4ZR
Check out the Reverse Beacon Network at
http://reversebeacon.net,
blog at reversebeacon.blogspot.com.
For spots, please go to your favorite
ARC V6 or VE7CC DX cluster node.
On 2/14/2013 3:08 PM, K9AY wrote:
W8JI said:
...(we probably all know) elongated loops are not really loops in
function. They are really phased verticals, and the horizontal part or
component of the conductors is simply a phasing line. K9AY's, Flags,
Pennants, EWE's, and other forms of elongated loops are really all
just phased verticals in function.
----
Not so. Time to put this misconception to rest.
Read my description of K9AY Loop operation in the most recent ARRL
Antenna Book and review the description of a DF loop with sense
antenna in that, or earlier antenna books.
I have never been able to achieve the same pattern as the loop using
close-spaced elements in a phased array. However, a model using a
small loop in combination with a nearby short vertical does indeed
result in the same pattern. (Feed them with equal currents and 90 deg.
phase shift.)
Magnetic lines of force from an arriving wavefront MUST induce
currents in a loop. You can't ignore them and assume that the vertical
end portions are the only place energy is captured.
73, Gary
K9AY
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