ELPRO Technologies ELP905K Spread Spectrum Radio Modem User Manual man FCC 905K 1 1

ELPRO Technologies Pty Ltd Spread Spectrum Radio Modem man FCC 905K 1 1

Yagi antenna with CC20 900 cable

905U-K.MAN Rev. 1.1 January 2002 ELPRO Technologies Pty Ltd Page 21Dipole and Colinear antennas. A unity gain dipole is the normal antenna for use on unlicensed channels. As it does notprovide any gain, then the power transmitted from the antenna will be the same as the powerout of the module. Dipole antennas are only available with a 15 feet of coaxial cable and SMAconnector for mounting away from the 905U-K module. Dipole antennas should be mountedvertically, at least 1 metre away from a wall or mast. For longer, more marginal radio paths higher gain colinear antennas can be used. These mustbe used with either CC10/900 or CC20/900 cable. 4mm21mDIPOLE AERIALMASTEARTH CONDUCTORSHOULD BE 16mm2EARTH STAKEIF GROUND CONDITIONS ARE POOR,INSTALL MORE THAN ON STAKEMAX. COAXIAL CABLE LENGTHS CC10/900 – 33 feetCC20/900 – 66 feetINSTALL AERIAL ABOVE LOCALOBSTRUCTIONSGNDANT905U.KSURGE DIVERTERCOAXIAL CABLESEAL CONNECTORSWITH “3M 23” TAPESTRESS REDUCTION LOOP The 905U-K normally produces 1.0 Watt of radio power when an external DC power supply isused. FCC regulations allow this power may be boosted to a maximum 4.0W by using ahigher gain antennas. These higher gain antennas may also be used to compensate for coaxialcable loss. The losses are 3dB for every 10m of RG58 cellfoil. If 10m of RG58 cable is usedon a marginal radio path, then a higher gain antenna may be used to cancel the losses in thecable and boost the transmitted power back to the maximum level. . YAGI antenna. YAGI antennas must only be used with a cable loss of 5dB or greater so the overall systemgain is less than 6dB. So they should only be used with a CC20/900 cable. YAGI antennas are directional. That is, they have positive gain to the front of the antenna,but negative gain in other directions. Hence YAGI antennas are normally installed with thecentral beam vertical and must be pointed in the direction of transmission to benefit from the

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