Maarten wrote:
"Do you have suggestions for antennas I should check out?"

I am listening to Radio Marti and too jammers on the same frequency.
Cuba is the target. Who knows where the transmitters are? Marti is said
to be in Miami but that is not necessarily its transmitter location.
Likewise the jammers may be in Cuba or elsewhere. LocaL Jammers must be
much more numerous to cover the same territory for a large area, but
they are more effective. The band is 25 meters, about 12 MHz, a
year-round performer.

Monitoring Radio Marti in Houston with a small battery portable complete
with its telescopic antenna convinces me that a listener is better
served using horizonta polarization due to the nulls off the antenna
tips which reject interference. The antenna should also be rotatable for
maximum signal and, or, minimum interference.

A large antenna is usually impractical to rotate. Curtains and rhombics
can have high gain and directionality. You can erect enough of these to
cover all azimuths desired, then you don`t need to rotate any antennas.
So many antennas are usually not possible for the amateur.

For the radio amateur, an assortment of Yagis mounted on rotators can
cover all desired frequency bands and directions effectively and
efficiently.

Best regards, Richard Harrison, KB5WZI