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Passive beam forming and spatial diversity in meteor scatter communication systems
Author(s) -
Akram Ammad,
Can Paul S.
Publication year - 1996
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/95rs03258
Subject(s) - antenna diversity , signal (programming language) , diversity gain , bandwidth (computing) , signal to noise ratio (imaging) , beam (structure) , telecommunications , fading , link budget , matrix (chemical analysis) , optics , computer science , physics , antenna (radio) , materials science , channel (broadcasting) , wireless , composite material , programming language
The method of passive beam formation using a four‐element Butler matrix to improve the signal availability of meteor scatter communication systems is investigated. Signal availability, defined as the integrated time that the signal‐to‐noise ratio (snr) exceeds some snr threshold, serves as an important indicator of system performance. Butler matrix signal availability is compared with the performance of a single four‐element Yagi reference system using ∼6.5 hours of data from a 720 km north‐south temperate latitude link. The signal availability improvement factor of the Butler matrix is found to range between 1.6–1.8 over the snr threshold range of 20–30 dB in a 300‐Hz bandwidth. Experimental values of the Butler matrix signal availability improvement factor are compared with analytical predictions. The experimental values show an expected snr threshold dependency with a dramatic increase at high snr. A theoretical analysis is developed to describe this increase. The signal availability can be further improved by ∼10–20% in a system employing two four‐element Butler matrices with squinted beams so as to illuminate the sky with eight high‐gain beams. Space diversity is found to increase the signal availability of a single antenna system by ∼10–15%, but the technique has very little advantage in a system already employing passive beam formation.