Cecil, W5DXP wrote:
"Have you ever actually tried one of those? (20 dBI gain for 200 degrees
of the horizontal, a loop closely coupled for supergain)"

Excellent question.

J.D. Kraus is the leading exponent of the "supergain antenna"(W8JK)
which he warns has a price in low feedpoint impedance, low efficiency,
and reduced bandwidth (higher Q).

Felow author F.E. Terman reiterates Kraus` caveats.

Kraus says the W8JK has a gain of 5.8 dBi. That is pretty good for two
1/2-wave elements and compares with a 3-element Yagi. When you replace
the straifgt elements in a Yagi with loops to make a "quagi" you may
gain about 2 dB. Design it for maximum gain, and you may pick up about 2
more dB. So, with a "supergain quagi" why wouldn`t you expect gain to be
limited tio about 10 dB.

The W8JK pattern is a figure-8 almost like a dipole but it gets 5-6 dBi
gain from reorientation of energy and that is 3-4 dB better than a
dipole. An array of two close-spaced quads will probably be sharper yet.
The W8JK pattern is shown in Fig 71 on page 8-50 of the 19th edition of
the ARRL Antenna Book. It seems to have about 100-degrees of beamwidth
in forward and reverse directions, so that may qualify as 200-degrees.

Best regards, Richard Harrison, KB5WZI