> >The K9AY can be "fixed" if you are willing to use additional
> >supports to make the loop square. The high angle response is
> >due to the sloping "verticals." However, given the performance
> >of the whip 4-squares, the effort is not justified.
>
> All the models I have of a K9AY (either delta or rectangle/square),
> EWE, and Flag have response at the zenith due to the current flowing
> in the horizontal wires (or the horizontal component of the current
> in the delta versions). I don't see any way to put a null straight
> up with these designs. It's always about 5 dB down from the peak
> signal. Do you have a model you can share that has a null at
> the zenith?
In fact, I use a K6SE "flag" in my modeling. It has the currents in
the top/bottom wires out of phase which results in the null (or a
substantially reduced response) at the zenith.
> >Yes, closer spacing produces better RDF for the K9AY and EQE arrays.
> >However, the closer spacing comes at a big cost in signal levels on
> >the lowest band - overall "gain" can be as little as -35 dBi which
> >then requires a rather stout, low noise, low IMD preamplifier or the
> >benefits of the array are lost in the IMD and preamplifier noise.
>
> A good point. There are always compromises to deal with when you
> attempt wideband designs.
A design that gets about 140' across the diagonal (1/2 wave on 80)
seems to be about as good as one can get for 160/80. Beyond that
point 80 meter pattern starts to fall apart and closer spacing
results in quite low signal levels on 160.
I'd really like to see some ideas for broadband passive feeds for
whip elements. A "matched" feedline is the one advantage of K9AY
or K6SE loops in these arrays.
73,
... Joe, W4TV
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