Masashi Mitsumoto

A low elevation target height measurement method using a complex angle error signal in a phase monopulse system

The monopulse method is widely used to obtain the arrival angle of a target echo, which is required in radar measurements of target height. The monopulse method uses the fact that the angle error signal obtained from the signals received by the sum and difference antenna patterns is a monotonically increasing function of the echo arrival angle. However, in measuring a low-elevation target, in addition to the direct echo from the target, the measurement is affected by indirect echoes arriving at the radar system after reflection from the sea or ground surface. In this case, the angle error signal is a complex function, which leads to a higher measurement error than the conventional monopulse method. In particular, if the angle range of the dual lobe (in the difference antenna pattern) is wider than that of the main lobe in the sum antenna pattern, the received signal for the difference antenna pattern suffers from interference with indirect echoes. This paper offers an analysis of the complex angle error signal in the monopulse method for such antenna patterns and proposes a method to obtain the direct echo arrival angle with suppressed interference from the indirect echoes. A computer simulation was used for comparison with the conventional method. It is confirmed that the proposed method yields reduced error.

FMCW automotive radars using only in-phase channel

This paper describes a novel Frequency Modulated Continuous Wave (FMCW) radar that is used only with in-phase channel. The merit of using the radar in this fashion is that it can suppress the ambiguity about range and target velocity, thus reducing performance deterioration. The radar is used in detection applications.