Topband: Boring Phased Array Update
Tree
tree at kkn.net
Sat Jan 12 11:20:01 EST 2008
Well - after a week of poor propagation to Europe, the band finally opened
up some last night and allowed a few European signals to make it to
Oregon. This allowed me to see if my phased array experiment was working
at all for signals coming in over the pole.
To review - I have two elements about 1/4 wave apart - one is a gamma matched
tower and the other is a wire tee element. Both have 40+ radials on them
with nice wet Oregon ground (and an assist from my septic drain field).
I measured a 30 degree phase "error" on the gamma matched tower and brute
forced the change by adding 30 degrees worth of coax to it.
The European signals were best in the end fire direction and very weak
off the back. This is the reverse of what the ZL test yielded, so I
feel that things are working somewhat.
G4AMT was able to hear me last night and this morning, I put RU3DX in the
log about 20 minutes before sunrise. What's even more telling, is that
the phased array is just about as effective on receive as the proven EU
beverage is. This has me very excited as it gives me two antenna for
RX - and I can fully use the 2nd receiver in the K3 for diversity
reception when it becomes available (another couple of months I believe).
So - I am not sure I will do much more tweaking on this array. I might do
some field strength measurements and perhaps tweak the length of the
phase delay line a bit in each direction to see if I can optimize on
F/B ratio.
73 Tree N6TR / 7
tree at kkn.net
Boring, OR
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