400MHz Omnidirectional Antennas

400MHz omnidirectional antennas operate in the 380–470 MHz frequency range, a spectrum valued for its excellent propagation characteristics—superior penetration through obstacles like buildings, trees, and terrain, compared to higher frequency bands. This makes them ideal for applications requiring reliable communication in challenging environments, such as public safety, industrial monitoring, and utility networks. The 400MHz band is widely used by emergency services (police, fire, ambulance) for two-way radio communication, as well as by utilities for smart grid and pipeline monitoring systems.

Design-wise, 400MHz antennas are typically larger than higher-frequency models due to the longer wavelength (approximately 75 cm at 400MHz). Common designs include whip antennas (for portable devices) and base station antennas with collinear dipole arrays for fixed installations. Base station models offer gains ranging from 3–10dBi, with the higher gain versions using stacked elements to enhance horizontal coverage while maintaining omnidirectional patterns. The vertical beamwidth is relatively wide (20–30 degrees), allowing for better coverage of undulating terrain or multi-story buildings.

Key specifications for 400MHz omnidirectional antennas include impedance (50 ohms), VSWR <1.5:1, and power handling capacity (up to 50 watts for base stations). They are often ruggedized for outdoor use, with corrosion-resistant materials (stainless steel, UV-stabilized plastics) to withstand harsh conditions. For public safety applications, these antennas support trunked radio systems (e.g., TETRA, DMR), enabling secure, group communication across large areas. In industrial settings, they connect remote sensors in mining, forestry, or agriculture, where line-of-sight is limited. The ability to penetrate foliage and structures makes 400MHz antennas indispensable for reliable low-data-rate, long-range communication in scenarios where higher frequencies would fail.