Wideband Multipath Propagation for Helicopter-to-Ground Telemetry Links

Abstract

This paper reports the analysis of L-band channel sounding experiments conducted along the flight line at Cairns Army Airfield, Ft. Rucker, Alabama. Propagation data from multiple antennas on a helicopter to multiple receiving antennas on the ground are used to compute power delay profiles. Analysis of the results reveals delay spreads of the multipath channels between 200 ns and 400 ns, with the longer delay spreads resulting when using a receive antenna with lower gain and higher sidelobe levels. The data also shows that on average, diversity signaling from three aircraft-mounted antennas can lead to gains in signal-to-noise ratio of approximately 13 dB, with the gain dependent on the multipath characteristics observed by the ground antenna.