[Andrew2]

I use a 40 foot vertical 'roach pole' antenna, inductively loaded about 30 feet up. A small adjustment coil at the base allows me to put the resonant point anywhere within the band. The 'earth mat' as I optimistically call it is about 100 sq ft of sturdy wire netting buried in the garden.
It seems to work reasonably well when fed with 30 watts of SSB from my homebrew transceiver and helps keep our local 1963 kHz AM net alive too.
The section above the loading coil consists of four parallel wires in an attempt to provide a bit more top capacitance.

This aerial is for transmit only as receiving on it is very noisy, so I use a Wellbrook loop for that.

I've tried the 'spiral top' idea and it worked a bit better, but the physical loading on the roach pole made me a bit queasy.