Fabry-Perot Antenna Employing Artificial Magnetic Conductors and Phase Gradient Metasurface for Wideband Monostatic RCS Reduction and High Gain Tilted Beam Radiation

Abstract

Platforms with low radar signatures require compatible antennas (low scattering) for communication purposes. Under this context, the article presents two Fabry-Perot (FP) Cavity antennas (Ant-1 and Ant-2). Ant-1's aperture is an integrated design of artificial magnetic conductor (AMC) surface and a phase gradient metasurface (PGM), incorporating three unit-cell structures. The antenna achieves reduced monostatic scattering over broad bandwidth, and simultaneously obtains high gain as well as tilted beam peak radiation. Patch radiating at 7 GHz forms excitation source of the cavity, and cavity height is 0.33λ, smaller than the heights of conventional cavity designs (λ/2). RCS reduction is obtained over a bandwidth of 105.8% (4-13 GHz) for arbitrary polarizations, covering C/X bands. Antenna gain is 12 dB, and peak radiation tilt is -60° in elevation plane. Simulations have been verified through fabricated prototype. Ant-2 is a modification of Ant-1. Ant-2's aperture is constructed from two unit-cell structures, and its aperture size is 41% smaller than Ant-1. Its cavity height is 0.3λ. Ant-2 also achieves wideband backscattering reduction; however, due to asymmetric layout of unit-cell elements over the aperture, radar cross section (RCS) reduction bandwidth is different for the two polarizations. For vertically polarized (VP) incident wave, RCS reduction bandwidth is 105.8% (4-13 GHz), but for horizontally polarized (HP) wave, it is 85.7% (5.2-13 GHz). Nevertheless, broadband RCS reduction is still achieved for both polarizations. Peak gain is 11.73 dB, achieved at -37° tilt angle. Simulations are presented for Ant-2. Compared to literature, both antennas show various improved results.INDEX TERMS artificial magnetic conductor (AMC), Fabry-Perot (FP) cavity antenna, phase gradient metasurface (PGM), radar cross section (RCS), tilted beam radiation

Realization of Deep Tilt Angle, High Aperture Efficiency, and Low Sidelobe Using a Single Metaplate and a Patch Antenna

“…In [14], [17], [18], θ 2 > 60 • is not met, although N metaplate = 1 is met. In [15], [16] and [19]- [21], the number of metaplates is N metaplate ≥ 2, which is against the main requirement of N metaplate = 1, and the aperture efficiency is low, i.e., it does not reach η aperture > 40%, despite of N metaplate ≥ 2.…”

“…Then, questions arise as to whether a single metaplate (N metaplate = 1) can realize a tilted beam whose direction is close to or greater than the current deep value of θ 2 = 60 • [16], [19], [21] with low sidelobe level; and at the same time, whether this beam-forming system can exceed a current aperture efficiency of η aperture = 40%. If these questions are resolved with constructive results, the cost of design and fabrication will be drastically reduced, and the potential for application to modern communication systems is increased.…”

A High-Gain Filtering Fabry-Perot Antenna With RCS Reduction

“…Since the AMC and PEC cells have opposite reflection phases, for any normal incident wave, the reflections from CAMS cancel out, and consequently, the monostatic RCS is reduced. Following this approach, many polarization conversion surfaces (PCS), which yield 180 ± 30 • reflection phase variations between two neighboring cells, have been used in FPAs to reduce RCS within a wide frequency range [11], [12], [13], [14], [15], [16], [17], [18], [19]. 3) Several other techniques were also applied in FPAs for RCS reduction, which include coding metasurface [20], [21], phase gradient metasurface [22], [23], receivertransmitter metasurface [24], phase delay line [25], asymmetric electromagnetic absorption [26].…”

Research on in‐band stealth of antenna based on phase gradient metasurface

“…For the second type of scattering, there are many ways to realize RCSR, such as polarization conversion metamaterial (PCM), [6][7][8] frequency selective surface (FSS), 9,10 artificial magnetic conductor (AMC), [11][12][13] and PGM. [14][15][16][17][18] Considering the scattering problem of the antenna, at present, achieving the in-band RCSR of the antenna is an urgent problem to be solved. Based on the principle of phase cancelation, Ren et al used PCM placed around the patch antenna to achieve RCSR in a wide band.…”

“…16 In Ref. 18, the antenna structure has integrated by AMC and PGM to realize monostatic scattering over broadband. At the same time, it has the characteristics of high gain and beam steering.…”