Wideband Multifunctional Polarization Converter: Application to Low Radar Cross-Section Radiating System

Abstract

In this article, a wideband linear-to-linear and linear-to-circular reflective polarization converter is discussed. The proposed polarization converter can efficiently convert an incoming wave with a linear polarization into a reflected wave with orthogonal polarization in the frequency ranges: 7.63–12.21 GHz and 19.34–21.2 GHz. Moreover, a circularly polarized reflected wave in the frequency band of 13.85–18.50 GHz is also obtained. The proposed polarization converter constitutes a split-ring and a metallic strip cut in the middle designed on an ultrathin single substrate layer (thickness of 0.079λ o, where λ o corresponds to wavelength at center frequency of lowest operational bandwidth). The study related to angular dependence of the proposed polarization converter is also carried out and a stability upto 15° is achieved at the lower and upper-frequency bands of operation, respectively. A prototype of the proposed polarization with 25 × 25 cells of the converter is fabricated and measured. Measurement results are in consensus with their simulated counterparts. Furthermore, a 12 × 12 array of the proposed polarization converter is used to study the radar cross-section (RCS) reduction ability of a microstrip patch antenna operating in X-band. The average RCS reduction of about 11 dBsm is obtained at normal incidence. The proposed polarization converter can be utilized in X/Ku/K frequency band applications. IMPACT STATEMENT The polarization property of an EM wave often needs to be modified to suit various applications, owing to its wide range of uses such as antenna radome, sensors, satellites, and radiometry. Frequency selective surfaces (FSSs) provide a simple and effective means to achieve this modification of the polarization property of an EM wave. Despite of number of polarization converters reported, there are still limited studies on multifunctionality, and with the advancements in technology, there is a growing desire for structures that can perform multiple functions like conversion of incident linear polarization to cross and circular polarization across a broader range of frequencies simultaneously. In this manuscript, a wideband multifunctional polarization converter functioning in reflective mode is presented. The proposed polarization converter can efficiently convert an incoming wave with a linear polarization into a reflected wave with orthogonal polarization in the frequency ranges: 7.63–12.21 GHz and 19.34–21.2 GHz and a circularly polarized reflected wave in the frequency band 13.85–18.50 GHz, respectively. Furthermore, a 12 × 12 array of the proposed polarization converter is used to study the radar cross-section (RCS) reduction ability of a microstrip patch antenna operating in X-band. The proposed polarization converter can be utilized in X/Ku/K frequency band applications.