Practical answer: For local VHF/UHF FM, a vertically polarized antenna above nearby obstructions is the normal starting point because mobile and repeater systems usually use vertical polarization.
What changes on the air
Height and a clear path often matter more than a small gain difference. A low antenna behind a roof, vehicle, or hill can lose the line-of-sight advantage that local FM depends on.
Plan the installation
- Use vertical polarization.
- Put the antenna safely above immediate clutter.
- Use low-loss feed line sized for frequency and length.
- Verify SWR at the antenna reference plane when possible.
Common mistakes
- Mounting beside metal without checking pattern change.
- Using long small-diameter coax at UHF.
- Assuming more transmitter power fixes a blocked path.
Technical boundary
General VHF/UHF antenna and transmission-line practice. Use the current product guide for exact dimensions, ratings, connectors, mounting, and supported configurations.
