Quick Answer
Antennas for LTE450 must be designed and tuned for the 450 MHz band. At this frequency, antennas are physically larger than higher-band equivalents: a half-wave dipole is approximately 33 cm long. For infrastructure deployments, sector antennas with 12-18 dBi gain are typical. For device-level installations, omnidirectional antennas with 3-5 dBi gain or directional panel antennas for remote sites are standard.
Antenna Fundamentals at 450 MHz
An antenna is a transducer that converts electrical energy to electromagnetic waves and vice versa. Antenna performance is characterised by several key parameters: gain (dBi), radiation pattern (omnidirectional or directional), bandwidth (the frequency range over which it performs within specification), VSWR (Voltage Standing Wave Ratio, a measure of impedance matching quality), and polarisation. At 450 MHz, the physical wavelength of 66 cm means that resonant antenna elements are substantially larger than at 900 MHz or 1800 MHz.
VSWR is a critical specification. A VSWR of 1:1 indicates perfect impedance matching (all power transferred to the antenna). A VSWR of 2:1 means approximately 11% of power is reflected (a loss of about 0.5 dB). For utility infrastructure, target a VSWR of 1.5:1 or better across the operating band. Verify VSWR specifications with measured data from the antenna manufacturer – published figures should come from a calibrated vector network analyser (VNA) measurement, not just theoretical calculations.
Base Station (eNodeB) Antennas
LTE450 base stations typically use sector antennas providing 60°, 90° or 120° horizontal beamwidth, mounted on a mast or tower at heights of 30-100m. A three-sector site uses three 120° antennas to provide 360° coverage. The antenna gain at 450 MHz for a standard sector antenna is typically 12-18 dBi, with the higher gains achievable from taller antenna arrays. MIMO operation (2×2 or 4×4) requires multiple antenna ports and either dual-polarised antennas or spatially separated single-polarisation antennas.
Device and CPE Antennas
For routers, gateways and IoT devices connecting to LTE450 networks, antenna selection depends on the installation environment. Options include: omnidirectional dipole or whip antennas (2-5 dBi) for devices with line-of-sight to the base station; panel antennas (6-12 dBi) for directional installations pointing at a specific base station; and magnetic-mount vehicle antennas for mobile applications. Antenna connector types at 450 MHz are typically N-type or SMA – verify the connector type on both the device and the antenna before ordering.
Frequently Asked Questions
Antenna dimensions are proportional to wavelength. At 450 MHz, the wavelength is 66 cm, so a quarter-wave antenna element is approximately 16.5 cm long. At 1800 MHz the quarter-wave element is only 4.2 cm. MIMO antenna arrays at 450 MHz are proportionally larger – this is a physical constraint of the frequency, not a design choice. Infrastructure masts must be engineered to handle the increased wind loading of larger antenna arrays.
For a substation at 30-50 km from the base station, a directional panel or Yagi antenna with 9-15 dBi gain, pointed accurately at the serving base station, is typically recommended. This directional gain compensates for the increased path loss at range and improves the SINR at the device, enabling higher modulation schemes and better throughput. A site survey or link budget calculation should be performed before specifying the antenna.