a:= 0.01 io do 3i1 41 i So i o a0 90 Incident A q k [ D e p ] Fig. 3. Output SINR (q2 = ..,' = 1.0).
NUMERICAL RESULTSFor the results presented, a six-element linear array of one-half wavelength spacing is used. The desired signal is assumed to be broadside along the array. The signal frequency is 50 Hz, and the sampling frequency is 1 kHz. Fig. 3 shows the output SINR as a function of the incident angle for input additive white noise levels when the desired signal variance a, ' and input interference variance U : are both 1.0. The output SINR decreases nearing the look direction because the constraint allows interference, as well as the desired signal, to pass in the look direction. The figure shows that the output SINR increases as the ihput interference-to-noise ratio (INR) increases. Also, the figure shows that the output SINR that can be achieved at a large angular separation of the desired signal and interference, is approximately 38 dB when the input S N R and INR are both 30 dB. The output SINR is a function of bandwidth, and hence, different results are obtained for wideband signals.
IV. CONCLUSIONSIn this communication, we have derived an expression for the output SINR of the linearly constrained beamformer in a noncoherent situation using the concept of vector space. The results show that the output SINR decreases as it approaches the look direction and increases as the input interference-to-noise ratio (INR) increases. If the correlation coefficients are included, the results could be extended to the case of coherent situations such as multiple propagation paths (multipaths) or smart jamming [51.
REFERENCES[l] 0. L. Frost, 111, "An algorithm for linearly constrained adaptive array processing," Proc. IEEE, vol. 60, pp. 926-935, Aug. 1972.[2] C. C. KO, "A fast null steering algorithm for linearly constrained adaptive arrays," IEEE Trans. , "On the performance of the generalized sidelobe canceller in coherent situations," IEEE Trans.Abstract-In a performance monitoring / fault isolation and correction (PM / FIC) system of a phased array antenna, a built-in transmission line embedded in the array aperture is used for signal injection to check the signal flow. In this paper we present an analysis of electromagnetic coupling between a Mn-lead transmission line and a dipole element. An analysis of the coupling between a transmission line and a linear array of dipole elements over a ground plane has also been developed. The calculated data compared with the measured data favorably. A development of microstrip-line signal injectors embedded in an aperture of a 2-0 array of monopole excited parallel-plate waveguides has also been made. Measurements of the feed and aperture distributions have been made and the measured distributions follow the designed feed distribution closely.