Spaced antenna diversity in temperate latitude meteor burst systems operating near 40 MHz: Variation of signal cross‐correlation coefficients with antenna separation

Abstract

We have studied 37‐MHz signals received over an 800‐km temperate latitude path using 400‐W continuous wave transmissions. Signals collected during a 9‐day period in February 1990 on two antennas at separations of 5λ, 10λ, and 20λ were analyzed. Three signal categories were identified (overdense, underdense, and not known (NK)) and cross‐correlation coefficients between the signals received by the two antennas were calculated for each signal category. No spatial variation, and in particular no decrease, in average cross‐correlation coefficient was observed for underdense or NK signals as the antenna spacing was increased from 5λ to 20λ. At each antenna separation the cross‐correlation coefficients of these two categories were strongly dependent on time. Overdense signals, however, showed no cross‐correlation time dependency at 5λ and 10λ, but there was a strong time dependency at 20λ. Recommendations are made in regard to the optimum antenna spacing for a meteor burst communication system using spaced antenna diversity. Our measurements support the views of Bartholomé and Vogt [1968], who suggested that a 4λ spaced antenna diversity configuration contributed to the exceptional signal throughput of the COMET meteor burst communication system.