> End-fire spacing improves the array in its vertical radiation pattern, but
> hardly at all in its horizontal pattern. This is how the model shows it,
> Tom. =====
Not really. Put one antenna in front of the other, align the
feedpoints in the same direction, and feed them 180 degrees out of
That forces a null in the sides, and results in the narrow front lobe I
> "He also could steer the nulls all around the antenna."
> I'd agree with you if the individual antennas in the array were
> nondirectional like verticals, but remember that here we're dealing with
> an array of antennas that are already unidirectional by themselves as a
> single antenna.
It doesn't matter if each cell has a null off the back, except that
prevents having response off the back if the null is very deep in
I do this all the time in commercial antennas, or my own antennas,
it not only models just fine, it also works quite well in practice.
>The individual parts of the array already have a F/B of >
> 40 dB. It's impossible to null the front of an array of non-rotatable
> Flags or Pennants and bring up the rear!! =====
Agreed. But you can certainly move an addition pair of nulls around
the antenna in any direction. That's basic to how the MFJ Noise
Canceller I designed works on groundwave noise.
> Maybe our disagreement lies in which end of the feedline you put the
> phasing device. I'm changing the phasing in my models right at the
> feedpoints of each element, with no feedline involved. Maybe it's a
> whole new ball game if the phasing device is at the receiver end of the
It makes no difference if a feedline is involved, except the feedline
reduces bandwidth stability of the null and can change the
requirements of equal voltage or equal current at the phasor
I phase two antennas through 2500 feet of cable, and also have
hase delays integrated right in some antenna cells.
This is old, time-proven concept right at the core of all directional
array design. Unless the broadside area is wide enough to force a
deep null in an area of major radiation, you are better off using end-
fire directivity and forcing a null in a side lobe that way.
This is a very well known effect.
73, Tom W8JI
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