super high frequency
The frequency area from 3 GHz through 30 GHz, commonly used for microwave devices, WLAN, and radars.
SHF: the microwave band that runs most wireless systems
Super high frequency (SHF) occupies the electromagnetic spectrum between 3 and 30 gigahertz. This range sits above ultra high frequency (UHF, which ends at 3 GHz) and below extremely high frequency (EHF, which begins at 30 GHz). Within this narrow but densely used band lie the frequencies that power most of the wireless systems you interact with daily: WiFi, Bluetooth, satellite communications, and weather radar all operate here.
The SHF band is attractive to engineers because wavelengths in this range are short enough to be physically practical for antennas and waveguides, yet long enough to propagate reasonably well through air and light rain. A 10 GHz signal has a wavelength around 30 millimeters, allowing compact antenna arrays and directive beams. This makes SHF ideal for point-to-point microwave links, which carriers use to backhaul data between cell towers across distances of several kilometers.
Within SHF, regulatory bodies have carved out licensed and unlicensed bands. The 2.4 GHz industrial scientific and medical (ISM) band is globally unlicensed and congested, shared by WiFi, Bluetooth, microwave ovens, and cordless phones. The 5 GHz WiFi bands are also widely available. Licensed bands include portions allocated to satellite downlinks, fixed microwave service, and military radar. Each allocation reflects a balance between utility and interference risk.
Practical limitations and design constraints
SHF equipment must manage attenuation and noise carefully. Free-space path loss grows with the square of frequency, so a 10 GHz signal loses more power over distance than a 1 GHz signal. Rain attenuation becomes noticeable above 10 GHz; heavy rain can reduce signal strength by 10 to 15 dB at 15 GHz. Connectors, cables, and circuit components must be precision-machined; loose connections or poor shielding cause leakage and cross-talk. Microwave ovens exploit SHF absorption by water molecules at 2.45 GHz, concentrating energy in a resonant chamber rather than radiating it through air.
The term "super high frequency" dates from post-1950s IEEE classifications and remains in use despite its vague superlative. It is often abbreviated SHF. Engineers may also refer to this band by its use case: "microwave," "K-band" (roughly 11 to 14 GHz), "Ku-band" (12 to 18 GHz), or specific application names like "WiFi" or "5G millimeter wave" (which technically extends into EHF but uses similar design principles). For manufacturing and compliance, knowing whether your equipment operates in SHF matters for emissions testing, antenna design, and regulatory filing.