The Inverted M I beleive the G0JJG 80m inverted M is unique. This antenna consists of a pair of short verticals, 10m tall, spaced 60ft (0.25 wavelengths approx) with two sloping wires suspended at 50  feet midway between the verticals. All four of these radiators are fed, using a crude coax arrangement. Despite this some high angle signals show over 25db front to back, dx generally 10 to 15 db. This is useful as it can reduce  close by signals more than the dx!

The verticals use a triangular topload, and you can just see the spacing bar (made from conduit lid) here.

This is how the antenna looks in eznec, using full size verticals.