"Richard Harrison" wrote in message
...
A single folded dipole is often wrapped into a halo shape with a small
gap between its ends for omnidirectional service and greater simplicity
than the turnstile. Capacitor plates are often added to the
short-circuited ends of the folded dipole to increase the capacitance
between its ends and thus improve current distribution which improves
pattern circularity. An array of such halos in a vertical stack can
provide gain by concentrating energy into a horizontal beam.
............................................

Richard,

For what it is worth, I ran EZNEC on a Squalo type 1/2 wave 6m antenna at 20
and 40 feet elevation. I made no attempt at matching or capacitive loading.
The gap at the ends was 2 inches.

1. Impedance at resonance was 10 Ohms. Reasonable for a 1:4 (12.5 : 50)
balun. I mention this, because it would be more rugged than a gamma match.

2. The azimuth plot was an ellipse, with a gain variation of 3 db between
the major and minor axis. Presumably capacitive loading would help this.

3. At 20 feet the lowest vertical lobe was at 14 degrees. At 40 feet, the
lowest vertical lobe was at 7 degrees, and it had many more lobes. I would
expect the M Squared antenna to have the same vertical, but not horizontal,
pattern.

Tam/WB2TT