Characteristic mode-based compact circularly polarized metasurface antenna for in-band RCS reduction

Abstract

This paper presents a novel design of a low profile circularly polarized (CP) metasurface (MTS) antenna with in-band radar cross-section (RCS) reduction property. The MTS is loaded as a superstrate on slot antenna and it can be viewed as a polarization-dependent MTS (PDMTS). The rectangular patch-based PDMTS is analyzed using characteristic mode analysis to find two orthogonal degenerate modes, which produces CP waves. Linearly polarized slot antenna is used to excite the PDMTS. The performance of PDMTS loaded slot antenna is analyzed numerically using full-wave analysis method. The PDMTS CP antenna is fabricated and its performance is tested experimentally. The proposed antenna has a compact structure and it has an overall size of $0.52{\lambda _0}\times 0.52{\lambda _0} \times 0.078{\lambda _0}$ (where ${\lambda _0}$ is the free space wavelength). The measured results show that the PDMTS antenna achieves $-10\,{\rm dB}$ impedance bandwidth of 29.41$\%$, 3-dB axial ratio bandwidth of 9.05$\%$, broadside gain of 6.34 dB, and monostatic RCS reduction of $-30.2\,{\rm dBsm}$ at the resonant frequency of 5.86 GHz. The simulated results are in well agreement with the measured results and it is well suited for C-band Radar and Satellite communication.

Circularly Polarized Antennas Using Characteristic Mode Analysis: A Review

“…Further, various MTS antennas have been proposed in the literature based on the orthogonality principle of surface current distribution and identical MS between adjacent or lower-order modes and higher-order modes [59][60][61][62]. A perforated H-shaped MTS [59] and a corner-truncated patch MTS with capacitive loading strips [60] have been proposed by exciting adjacent higher-order modes and lower-order modes, respectively.…”

Design of circularly polarized planar leaky‐wave antenna using characteristic mode analysis

“…The unit cell is analysed using an in‐house MATLAB CMA code. Since numerous papers have described the CMA [13–20], the details of the CMA method are not provided here. In CMA, the generalized eigenvalue equation is given by, where is the eigenvalue.…”

“…Garbacz proposed the characteristic mode analysis (CMA) for the first time in 1965 [13]. In recent years, CMA has been the subject of intense research in the field of antenna engineering [14][15][16][17][18][19]. The CMA is a systematic method to design antennas while providing a physical insight of the structure design.…”

“…The method provides a clear understanding of the structures radiating modes, the modal current distribution of each radiating mode, and the far-field radiation pattern of each mode. These specifications can be an important guide for designing an antenna with an optimized performance by offering the appropriate feed point, achieving CP radiation, increasing bandwidth, and so on [14][15][16][17][18][19]. In [20], two commonly used antennas with CP radiation, namely the E-shaped patch antenna and U-slot patch antenna were optimized using the CMA.…”

“…In [20], two commonly used antennas with CP radiation, namely the E-shaped patch antenna and U-slot patch antenna were optimized using the CMA. In [19], a CP meta-surface antenna was analysed by applying the CMA to excite two orthogonal modes to obtain the CP radiation. In [18], inspired by the CMA method, a dual-band antenna was designed.…”