What are the exact frequency ranges for VHF and UHF?

By ITU definition, VHF spans 30-300 MHz and UHF spans 300 MHz-3 GHz. Land mobile radio in practice uses narrower slices within each: VHF LMR is commonly 136-174 MHz, and UHF LMR commonly uses 380-512 MHz plus the public-safety 700/800/900 MHz bands.

Why does a hill affect VHF and UHF differently?

Diffraction around an obstacle works best when the obstacle size is on the same order as the wavelength. A hill or ridgeline is large compared to both bands' wavelengths, but VHF's longer wavelength diffracts around that kind of large, gradual obstruction more efficiently than UHF's shorter wavelength does, giving VHF a real open-terrain range advantage at equal transmit power.

Is UHF always the right choice for public-safety in-building coverage?

It's the common default because its wavelength diffracts efficiently through typical windows, door gaps, and interior partitions, but it is not universally superior. Heavily rebar-reinforced concrete can attenuate UHF more than VHF in some cases, because standard rebar mesh spacing is closer in scale to UHF wavelengths. In-building system design should verify measured signal strength against code requirements (e.g., NFPA 1221 / IFC 510) rather than assume a band choice alone guarantees coverage.

Does a higher frequency always mean shorter range?

In free space, higher frequency does mean higher free-space path loss for a given distance (per the Friis equation), which reduces range at equal transmit power and antenna gain. But real-world range also depends heavily on diffraction and obstruction behavior, not just free-space loss — which is why VHF's range advantage over hilly terrain is about more than just path loss alone.

Why are UHF antennas physically smaller than VHF antennas for the same gain?

Antenna element dimensions scale with wavelength — a common quarter-wave or half-wave element is a fixed fraction of λ. Since UHF's wavelength is roughly a third to a quarter of VHF's, a UHF antenna achieving comparable gain and pattern can be built noticeably smaller, which is one practical reason UHF antennas are easier to conceal in ceiling tiles and equipment risers for DAS deployments.

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Concept Explainer · Radio Communications

UHF vs. VHF

Why the "better" band depends on whether the signal has to cross open terrain or squeeze through a building — a single wavelength number drives both answers.

VHF (very high frequency, roughly 30–300 MHz — land mobile radio commonly uses 136–174 MHz) and UHF (ultra high frequency, roughly 300 MHz–3 GHz — LMR commonly uses 380–512 MHz and 700/800/900 MHz public-safety bands) aren't just two labeled dials on a radio. The frequency difference sets a real, physical wavelength difference, and that wavelength is what actually decides how a signal behaves once it leaves the antenna — how far it carries across open ground, how well it diffracts around hills and tree lines, and how easily it slips through windows, wall cavities, and stairwells once it reaches a building.