Antennas 90 feet and shorter are able to self Support between two end poles, although greater wind/ice survivability is achieved with a three pole installation.
The 180 foot antenna must have a center support. You should use the FLDP CM center mount to attach any of these antennas to a center mast. The 90 foot antenna is the minimum length recommended to perform nighttime NVIS well. The 180 foot antenna has enhanced performance at the low end.