Adaptive Suppression of Interference in HF Surface Wave Radar Using Auxiliary Horizontal Dipole Antennas.
DEFENCE RESEARCH ESTABLISHMENT OTTAWA (ONTARIO)
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This report presents the results of a study to evaluate the effectiveness of an adaptive technique using horizontal dipoles to suppress the skywave interference in HF Surface Wave Radar HFSWR. Four auxiliary horizontal dipole antennas, configured in the form of two separate crosses, were used to form an adaptive system with the vertically polarized antennas VPA of a HFSWR system. The outputs of the horizontal dipoles were correlated with the summed output of the VPAs to cancel the interference component in the output of the VPAs. Two slightly different methods were used in the estimation of the correlation coefficients. The first method used the samples at the far ranges of the radar, and the second method used the samples in the range bins close to the range bin selected for the interference suppression. With the first method, the interference-plus-noise power INP was reduced by up to 13 dB, and the Bragg-to-interference-plus-noise-ratio BINR was increased by up to 21 dB. With the second method, the INP was reduced by up to 17 dB, and the BINR was increased by up to 25 dB. In both methods, we compared the effectiveness of the adaptive technique using one, two or four horizontal dipole antennas. As expected, we found that the technique was the most effective when all the four horizontal dipoles were used.
- Active and Passive Radar Detection and Equipment
- Radiofrequency Wave Propagation