In this paper we present the results of the research on radar target elevation estimation in the near field of the vertical line array antenna. In particular, we examine the case of targets at low elevations where coherent reflections from ground prevent accurate measurements of target angular positions. The estimation method used is a modified version of the MUSIC algorithm, adapted for the application in the near field antenna environment. A spatial smoothing preprocessing scheme has been applied in order to resolve close coherent signals. The algorithm has been successfully applied go both simulated and recorded radar data. Controlled Ku-band radar experiments were conducted at the Valley Forge Research Center of the University of Pennsylvania. Estimation of actual target elevations to within 1 standard beamwidth has been achieved for SNR's of about 0 db.

The analysis and optimization of digital matched filters (DMF's) with multilevel quantizers, which are matched to multilevel amplitude and phase modulated (AM/\phi M) signals, are considered here. Quite general expressions for the DMF's output signal-to-noise ratio (SNR0) have been obtained for the case in which the interference has a symmetric, differentiable probability density distribution. For such interference, SNR0has been shown to be separable into two factors, which respectively represent the effects of the quantization and correlation operations of the DMF. The two factors can be optimized independently of each other. In particular, the optimal quantizer strategy for Gaussian interference is proven to be (within the limits of practical approximation and also asymptotically) one with equal spacings of the quantizer levels and thresholds. All the SNR0calculations have been carried out for a complex outputXrather than the commonly used real-valued, physical outputZ. The validity of the relationshipSNR_{0}X = 2 SNR_{0}Zhas been proven for all types of interference considered in this work. Finally, the optimalSNR_{0}Xfor Gaussian interference has been proven to be bounded from above bySNR_{0}Xfor the analog matched filter and from below by that of DMF with hard limiter as a quantizer.