9.4.11
COAX, CONNECTORS:
50 Ohm coax connectors of a good quality should be used, termination must be in accordance with the
manufacturer's specification, any special tools required to terminate the connectors must be used.
Connectors exposed to the environment should be sealed to prevent the ingress of moisture. If the cable
is penetrated by water a high loss will occur and the cable will need to be replaced. Once assembled it
is advisable to test the cable and connectors for open and short circuits.
9.4.12
VSWR MEASUREMENT:
Voltage standing wave ratio (VSWR) is the ratio of detected volts from the forward RF power, to the
detected volts from the reflected (returned) RF power. This ratio is used to measure the combined coax
cable and antenna match. A good match will ensure that most of the RF Power is radiated, whereas a
bad match will result in the reflection of a large amount of the power, thereby reducing the transmitter's
range. A perfect match will give a 1:1 ratio and bad match will give 2:1 or higher. For guidance, a good
system will measure between 1.2:1 and 1.5:1.
9.4.13
LIGHTNING ARRESTERS
At high or exposed sites, the use of a lightning arrester is recommended. This in-line device fits
between the antenna and the product with an earth strap connected to ground. Should a lightning strike
occur, most of the energy should be diverted to ground leaving the equipment with little or no damage.
URT500 Manual
Page 39 of 42
Rev. C – 6 August 2008
