Nigel Molesworth wrote:
"I don`t have space to mount a 1.5 m. antenna--."

In any direction? Well Nigel is in luck anyway as a quarterwave antenna
worked against a counterpoise or groundplane workes about as well as a
halfwave vertical antenna. Automobile antennas work as a vertical over a
groundplane of sorts. If the antenna is too short, it picks up less
signal but the receiver usually is quiet and has surplus gain so the
problem is unimportant.

Only 75 cm or 30 inches is required for 1/4-wavelength which is resonant
at 100 MHz over a good ground of the right sort.

As few as two 30-in. wires laid horizontally in opposite directions may
serve as a counterpoise to a 30-in. vertical antenna.

Receiving antennas are usually very tolerant but need to be kept away
from large noise sources.

Best regards, Richard Harrison, KB5WZI