Topband: Phased "Flags"

[Larry Molitor]

Still pursuing the optimum RX antenna system for my QTH, I put up a pair of 
Flags spaced 315 feet and fed in phase for broadside operation. (equal 
lengths coax to a 0° splitter/summer) Initially pointed west, performance 
seemed to be about what I expected, both on the few DX stations I heard and 
on the BC station on the top end of the AM band.

After a few days of listening to nothing, I swapped ends of the flags and 
pointed them east. Performance was not what I expected after the swap. It 
took me a while, but finally figured out that I had the matching/isolation 
transformers incorrectly wired. With the transformers "phased" wrong, the 
Flags were fed 180° instead of in phase. Why they seemed to work pointed 
west and then did not when pointed east is a mystery to me.

The broadside configuration was selected for the good null off the side of 
the pattern. 315 foot spacing was used because of the plots presented in 
K6SE's QST article. After a lot of testing, it appears that 315 feet might 
be too wide to achieve the performance I want. The front lobe seems 
narrower and the side nulls don't seem to be as deep as I hoped for. Since 
I still don't have my modeling capability back, I wonder if anyone has 
played with the spacing on these ground independent RX antennas and has any 
suggestions. I still have time to change the spacing once before the Stew 
Perry run, but don't want to guess.

Thanks.

73 & HNY,

Larry - W7IUV


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