Comparative study of two approaches in improving cross range resolution for an imaging antenna
The high resolution bearing of an antenna is of great importance in many practical applications, especially in microwave imaging. The angular resolution is related to the size of the antenna, but the increase of antenna size is often limited. For a real aperture antenna, the deconvolution technique was used to equivalently enlarge the size of the aperture resulting in the improvement of angular resolution. Unfortunately, in this technique, the requirement of the signal to noise ratio (SNR) is quite critical. In a previous report, a new technique of super-resolution bearing for a real aperture antenna was proposed by Fang, Sheng, Li and Zhang (see Proceedings of The Sixth AJU-FIT-NUST Joint Seminar, p.191-6, 1996). In this technique, the aperture distribution is obtained by processing the receiving signal of antenna during azimuth scanning and then super-resolution azimuth distribution is achieved by using nonlinear spectrum estimation. We call this technique the aperture distribution reconstruction and nonlinear processing method (ADRNPM). Numerical simulation shows the requirement of the SNR for our technique is much looser and the technique can be readily transferred to the conventional radar to improve the angular resolution. Some experimental results are presented which shows the realizability and validity of this new technique. Moreover, the resolution and antinoise performance are compared numerically and some useful conclusions are obtained.