RCS reduction of array antenna using circulator and phase shifter

This paper presents RCS reduction technique of array antenna using circulator and phase shifter. In this RCS reduction technique, the antenna mode scattered field, which is the re-radiated field of antenna, is controlled by the phase shifter to cancel out the structural mode scattered field. In this paper, a measurement method is proposed to measure the amplitude and phase of the antenna mode of each element and the structural mode of the whole array for the deterministic RCS reduction. A RCS synthesis method is also proposed to achieve wide angle RCS reduction. The effectiveness of the proposed methods are demonstrated by experiments using an 8-element array antenna with circulators and digital phase shifters.

I. Introduction

Reduction of radar cross section (RCS), or scattered field of antennas has recently received more attention [1]–[3]. It is known that the scattered field by antennas consists of two components: the structural mode and the antenna mode [4]. The structural mode is due to interaction between the incident field and the antenna structure. The antenna mode is due to reradiation of antenna, and which is associated with the antenna radiation property and loaded impedance. The impedance loading is the most popular RCS reduction technique in which the antenna mode is adjusted to cancel out the structural mode by the loaded impedance. However, this technique is not so effective when the structural mode is larger than the antenna mode (e.g., when antenna is installed on a large structure).