Measurement of the array-antenna directional pattern and bit error rate of a space-time equalizer

Array-antenna directional patterns of a pair of constrained array processors used in a space-time (ST) equalizer and the bit error rate (BER) of the ST equalizer were measured in an anechoic chamber. One of the constrained array processors constrains the direct path and the other constrains the one-symbol delayed path. The one-symbol-spaced two-taps-Viterbi-equalizer was used in the ST equalizer for obtaining path diversity from the direct and one-symbol-delayed paths. The measurements were conducted in static multipath environments where the direct path, one-symbol, and two-symbol delayed paths with critical angles of arrival (AOA) were generated. The array-antenna directional patterns and BER of a non-constrained array-processor were also measured and compared with those of the ST equalizer. The center of the carrier frequency was 3.35 GHz and the 99%-occupied power bandwidth was 2.7 MHz. The measured results indicate that the pair of the array-antenna directional patterns of the pair of the constrained array processors provides large gains in the directions of both direct and one-symbol-delayed path. The ST equalizer thus has significantly lower BER than the non-constrained array processor. However, degradation of null-forming in the direction of the interference occurred because of the transmitted signal bandwidth.