There is no free lunch with directivity.
In order to have a narrow pattern, you need physical space in the array.
You can get a big improvement if you have noise mostly arriving from one
fixed direction that can be nulled by the sharp null of a loop (or an EWE
which acts like two close spaced verticals with near perfect phasing).
Spacing two antennas 5/8 wl broadside, or multiple antennas placed over a
distance end-fire, will drastically improve performance. The narrower the
main lobe and cleaner the pattern, the larger and more reliable the
improvement. What the element is hardly matters, if things are done
correctly. Directivity is ultimately the only thing that matters, and it
takes physical space to successfully produce a narrow clean pattern.
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