> Doesn't this apply to a delta too ?
All of this applies to a "delta" (triangular, apex up) loop. Other
formats of vertical loops have different rules for feeding to maximize
vertical polarization ... for example a diamond (square) loop would be
fed at one of the "side" corners and a square or rectangular loop
(e.g., hung between two towers) would be fed in the center of one of
the [vertical] sides.
In most cases, (unless one has a tower more than 150 feet tall) the
loops will be somewhat "squashed" for 160 (flatter than optimum). An
equilateral delta will be on the order of 160 feet tall; a "diamond"
will be nearly 200 feet tall.
73,
... Joe, W4TV
On 5/26/2016 2:23 PM, Bob K6UJ wrote:
Joe,
I am in the planning stage of trying a delta loop, apex up.
Doesn't this apply to a delta too ? For vertical radiation, feed 1/4 wave
down from the top (apex) ?
Bob
K6UJ
On 5/26/16 9:58 AM, Joe Subich, W4TV wrote:
On 5/26/2016 12:31 PM, Jim Thomson wrote:
## Instead of feeding in the lower corner, if you really wanted 100%
true vert radiation, then feed it part way up on one side. I believe
it had to be fed 1/3 the way up one side of the loop. Then route
the coax straight across from the elevated feedpoint....to the
tower, then down the tower to shack.
That depends on the aspect ratio of the loop. The correct feed point
for maximum vertical polarization is 1/4 wave down from the apex. If
you have a true equilateral triangle, the feedpoint will be 1/3 of the
way up from the corner ... if the loop is "flatter" (lower tower) the
feedpoint will be farther from the corner.
73,
... Joe, W4TV
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