LOW-COST L-BAND MOBILE TERMINAL ANTENNAS FOR HELICOPTERS

The feasibility of using a low-gain antenna (LGA) as a mobile terminal antenna for helicopers is described in this article. The objectives a re (a) to select the lowest cost antenna system which can be easily mo unted on a helicopter and capable of communicating with a satellite, a nd (b) to determine the best antenna position on the helicopter to mit igate the signal blockage due to rotor blades and the multipath effect from the ehlicopter's body. The omnidirectional low gain antenna (LGA ) is selected because it is simple, reliable, and low cost. The helix antenna is selected among the many LGAs because it is the most economi cal and has the widest elevation beam-width. Both two- and four-arm he lices are studied experimentally to determine the antenna's performanc e and the scattering effects from the helicopter's body. It is found t hat the LGA should be located near the tail section and at least 8 in. above the helicopter. (C) 1993 John Wiley & Sons, Inc.