What antenna polarization is normally used for long-distance CW and SSB contacts on the VHF and UHF bands?
Why By long-standing convention, VHF/UHF weak-signal work using CW and SSB is done with horizontally polarized antennas, so beams, Yagis and loops for those modes are mounted with the elements parallel to the ground. Horizontal polarization also tends to pick up less man-made noise and suffers less ground-reflection loss over long paths. Matching polarization matters because a cross-polarized station can be 20 dB or more weaker, so everyone sticks to the same standard.
Watch out Vertical is the normal choice for FM repeater and mobile operating on VHF/UHF, not for long-haul SSB/CW; circular polarization is mainly used for satellite work, where the spacecraft's orientation keeps changing.
Horizontal for weak-signal SSB/CW, vertical for FM repeaters, circular for satellites.