Question T3A03
From subelement T3 - T3A
What antenna polarization is normally used for long-distance CW and SSB contacts on the VHF and UHF bands?
Why is this correct?
Horizontal polarization is used for long-distance VHF/UHF CW and SSB contacts because operators typically use beam antennas for these weak-signal modes, and beam antennas are much easier to mount and operate horizontally than vertically. Horizontal polarization also picks up less man-made noise and takes better advantage of atmospheric propagation effects. Circular polarizations are primarily used for satellite work, while vertical polarization is standard for FM repeater operations.
Memory tip
Remember the application drives the polarization choice: FM/repeaters use vertical for compatibility, while weak-signal work uses horizontal for performance. The physical practicality of mounting large directional antennas often determines the polarization standard for each operating mode.
Learn more
In amateur radio practice, horizontal polarization provides several technical advantages for weak-signal VHF/UHF operations. It typically exhibits lower man-made noise pickup compared to vertical polarization, since most electrical interference sources radiate vertically polarized signals. Additionally, horizontal polarization can better utilize certain propagation modes like tropospheric enhancement and aircraft scatter. The emission standards for CW and SSB on VHF/UHF frequencies remain identical regardless of polarization, but the improved signal-to-noise ratio from horizontal mounting makes it the preferred choice for DX work.
Think about it
Why do you think beam antennas used for weak-signal work are easier to mount horizontally, and how might this physical constraint have influenced the polarization standard for VHF/UHF DX?