[Lowfer] loop info

[Bill Ashlock]

Bob,

>I have looked into the archives and found the 1991 ( ? ) QST article on a
>small 160 meter TX loop. This was by W1LYQ and at the time of enough 
>interest for me to
>save.the loop is made from 8, 10 Ft sections of 1 inch copper pipe and fed
>with a link coupler the point of interest is the statement that ' in order 
>to max the low
>angle radiation " the loop tuning cap should be mounted at the top of the 
>loop .

>Now I realize this size loop is much bigger at 160 , compared to the 50 Ft 
>loops being used on
>185 Khz but I wonder if this also holds true on LF.

From all I've read on VERY Smaaaall loops, as we have with our 50/50s at 
185, the location of the feed or the tuning capacitor should make no 
difference. This because the current is essentially constant over the full 
length of the loop. 160M is of course 10 times higher in freq and the 
current is beginning to taper off in some portions of the loop you describe 
(Actually the same size as my test loop).

" T Hart ,, small High Effency Loop Antennas ,,The ARRL Antenna Book
16 Th Edition 1991 "

Yes, I think I have this same article in my older Antenna Book. He talks 
about a 6db gain when using a ground screen but my later Antenna Book does 
not say anything about a screen. It's my theory that at LF the ground itself 
acts as a ground screen to the loop and this accounts for the higher than 
predicted radiation resistance that I measure. The latest statements by Mr 
Hart relative to cross field antennas, unfortunately, have effected my trust 
in his pioneering loop efforts.

Bill

PS: I just finished linking up a continuous 480' run of #8 over the tops of 
~30 trees. Later I'll work on the lower section comprised of #12 triple 
ladder line which needs some piecing together. So far I haven't had to buy 
any wire. Maybe tomorrow I'll be able to tune it up and at least make an Rac 
measurement - then the real test with an actual signal. Exciting stuff!

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