Radio Frequency Bands
Antenna names and specs are full of labels like HF, VHF, and UHF. They are just shorthand for where a signal sits on the radio spectrum — and that single fact drives how big an antenna must be, how far the signal travels, and what it is good for. This page is the key that makes the rest of the catalog make sense.
Frequency and wavelength
A radio wave has a frequency (how many times per second it oscillates, measured in hertz) and a wavelength (the physical distance between two wave crests). They are tied together by the speed of light:
wavelength (m) ≈ 300 ÷ frequency (MHz)
So a 3 MHz signal is about 100 m long, while a 3 GHz signal is only about 10 cm long. This is the crucial link to antennas: an efficient antenna is sized in proportion to the wavelength (often a half or a quarter of it). Low frequencies need big antennas; high frequencies fit tiny ones. That is why an AM broadcast tower is a hundred metres tall, while the Wi-Fi antenna inside your phone is a few centimetres.
The bands at a glance
| Band | Frequency | Wavelength | Typical uses |
|---|---|---|---|
| VLFVery Low | 3–30 kHz | 100–10 km | Submarine comms, navigation beacons. |
| LFLow | 30–300 kHz | 10–1 km | Longwave broadcast, time signals (WWVB). |
| MFMedium | 300 kHz–3 MHz | 1 km–100 m | AM broadcast, maritime and aviation beacons. |
| HFHigh | 3–30 MHz | 100–10 m | Shortwave broadcast, long-distance amateur radio — waves bounce off the ionosphere for worldwide range. |
| VHFVery High | 30–300 MHz | 10–1 m | FM radio, TV, air traffic control, 2 m amateur — mostly line-of-sight. |
| UHFUltra High | 300 MHz–3 GHz | 1 m–10 cm | TV, cellular, Wi-Fi, GPS, Bluetooth — compact antennas, line-of-sight. |
| SHFSuper High | 3–30 GHz | 10–1 cm | Satellite, radar, microwave links, 5 GHz Wi-Fi — dishes and horns. |
| EHFExtremely High | 30–300 GHz | 10–1 mm | Millimetre-wave 5G, automotive radar, research. |
Band edges follow the ITU convention. The three highlighted bands — HF, VHF, and UHF — cover most of the antennas in this site.
Why the band changes the antenna
- Size. Because an antenna scales with wavelength, the same design (say a half-wave dipole) is metres long on HF but centimetres long on UHF. Lower bands force big wires, masts, and towers; higher bands allow PCB-printed patches.
- How far it travels. HF signals can refract off the ionosphere and skip around the planet. VHF/UHF generally go line-of-sight to the horizon. SHF/EHF are easily blocked by walls, rain, and terrain, so they favour short, focused links.
- How tightly you can focus. A reflector or array many wavelengths across produces a narrow beam. At high frequencies the wavelength is small, so even a modest dish spans many wavelengths and achieves very high gain — which is why microwave dishes are so directional.
Ready to see it in action? Browse the antenna catalog and notice how each antenna's frequency band matches its size and shape — or start with the trainings.