Radio Modem Antenna Products

Radio Modem Antenna Mounting

Antenna should be mounted as high as possible in a clear area as far away from obstructions such as metal clad buildings and foliage.

Wireless Modem Antenna Feeder Cable

When designing a radio system the manufacturers data on 50 ohm coaxial cable must be referred to. The antenna feeder cable should be kept as short as possible. As a general rule, with 50 ohm low loss coaxial cable, half the power (3dB) will be lost every 10 - 20 metres.

Radio Modem Antenna Connectors

50 ohm coaxial connectors of good quality should be used. Termination must be in accordance with the manufacturers specification. Connectors exposed to the environment should be sealed to prevent the ingress of moisture. If the cable is penetrated by moisture an impedance mismatch will occur dramatically reducing the signal propagation. The cable will then have to be replaced.

Radio Modem Antenna Measured VSWR

The Voltage Standing Wave Ratio (VSWR) is the ratio of detected volts from the forward RF power, to the detected volts from the reflected RF power. In perfect antennas system all the RF power will be radiated by the antenna giving a VSWR of 1:1. If most of the RF power is reflected back into the transmitter then the VSWR will be 2:1. A good antenna system will have a VSWR of between 1.2:1 and 1.5:1.

Radio Modem Antenna Lightning Arrestors

At exposed antenna installations a lightning arrestor should be installed. This is connected in line with the antenna feeder. The case of the arrestor is connected to a solid earth. Should lightning occur, most of the energy will be diverted to ground thereby protecting the radio equipment.

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