Yongtao Jia

Wideband RCS Reduction of a Slot Array Antenna Using Polarization Conversion Metasurfaces

A new approach to reducing the monostatic radar cross section (RCS) and preserving the radiation characteristics of a slot array antenna by employing polarization conversion metasurfaces (PCMs) is presented in this communication. The PCM is arranged in a chessboard configuration consisting of fishbone-shaped element. It is placed on the surface of the slot array antenna. The characteristics and mechanism of the RCS reduction are analyzed. Simulated and experimental results show that the monostatic RCS reduction band of the antenna with PCM ranges between 6.0 and 18.0 GHz for normally impinging both x- and y-polarized waves. The radiation characteristics of the antenna are well preserved simultaneously in terms of the impedance bandwidth, radiation patterns, and realized boresight gains.

Broadband Polarization Rotation Reflective Surfaces and Their Applications to RCS Reduction

A novel broadband polarization rotation (PR) reflective surface (PRRS) with a high polarization conversion ratio (PCR) is proposed, which can reflect the linearly polarized incident wave with 90° PR. The proposed PRRS consists of a periodic array of square patches printed on a substrate, which is backed by a metallic ground. By connecting the square patch with the ground using two nonsymmetric vias, a 49% PR bandwidth is achieved with a high PCR of 96%, which is a significant improvement from the state-of-the-art 29% PR bandwidth. Moreover, the frequency responses within the operation frequency band are consistent under oblique incident waves. Furthermore, another ultra-wideband PRRS with a periodic array of quasi-L-shaped patches is proposed, which increases the PR bandwidth further to 103%. In addition, the designed PRRS is applied to wideband radar cross section (RCS) reduction. Different arrangements of the unit cells of the PRRS are proposed and their effects on RCS reduction are investigated. To validate the simulation results, prototypes of the PRRSs are fabricated and measured. The measured results are in good agreement with the simulated ones.

Low-RCS, High-Gain, and Wideband Mushroom Antenna

In this letter, a high-gain and wideband mushroom antenna with wideband low radar cross section (RCS) is presented. The mushroom structure is resonant at the antenna operating frequency, and the in-band RCS can be reduced significantly. The bandstop frequency selective surface (FSS) designed at the operating frequency of the antenna is used to replace the metallic ground of the antenna so that the out-of-band RCS of the proposed antenna can be reduced while maintaining the high gain. Furthermore, square metallic patches printed periodically below the cells of the FSS are utilized to add a new zero-degree reflection phase in the desired frequency range to enhance the bandwidth of RCS reduction. As a result, a wideband RCS reduction can be achieved both in and out of antenna operating frequency band. The results show that the RCS of the proposed antenna is dramatically reduced over a wide frequency range, compared to the traditional patch antenna.

Printed UWB End-Fire Vivaldi Antenna with Low RCS

A novel Vivaldi antenna with low radar cross section (RCS) for ultra-wide band (UWB) applications is proposed in this paper. As a printed antenna with electrically large length, the Vivaldi antenna has large backscattering when the incident waves are in the grazing directions. By sleeking the edges of the proposed antenna, the re∞ected currents are reduced so that the peaks of the backscattering can be inhibited. Its radiation characteristics are simulated and verifled. The RCS performance of the proposed antenna is studied and compared with that of a commonly used Vivaldi antenna. The result shows that the proposed antenna has lower RCS than the reference antenna in both the perpendicular and grazing directions while maintaining similar radiation characteristics. So the results illuminate that the proposed Vivaldi antenna is a good candidate in the design of printed UWB end-flre antennas requiring low RCS.

Ultra-wideband and high-efficiency polarization rotator based on metasurface

An ultra-wideband and high-efficiency polarization rotator based on a metasurface is proposed in this paper. The unit cell of the proposed polarization rotator consists of two pairs of L-shaped metallic patches printed on a substrate, which is backed by a metallic ground and covered by a superstrate. The superstrate is composed of a dielectric layer and a pair of L-shaped metallic patches printed on the dielectric layer. The proposed polarization rotator can rotate the polarization of linearly polarized electromagnetic (EM) wave to its orthogonal counterpart after reflection when the incident EM wave is y-/x-polarized. Simulated results show that the polarization rotator can perform 90° polarization rotation with very high efficiency at seven different frequencies and achieve a polarization conversion ratio higher than 0.9 in the frequency range of 7.8–34.7 GHz at normal incidence. Good agreement between the experimental results and simulated ones has been obtained.

A Dual-Patch Polarization Rotation Reflective Surface and Its Application to Ultra-Wideband RCS Reduction

An ultra-wideband polarization rotation reflective surface (PRRS) with a high polarization conversion ratio (PCR) is proposed, which can reflect a linearly polarized incident wave with 90° polarization rotation. The unit cell of the proposed PRRS consists of a square and L-shaped patches printed on a substrate, which is covered by a superstrate and backed by a metallic ground. The two patches are connected to the ground using two metallic vias, respectively. Compared with the previously reported PRRS, the polarization rotation bandwidth of the proposed PRRS is enhanced from 49% to 97% with a high PCR of 96%. The frequency responses within the operation frequency band are consistent under oblique incident waves. Furthermore, the designed PRRS is applied to the ultra-wideband radar cross-section (RCS) reduction by forming a checkerboard surface. A 10-dB RCS reduction is achieved over an ultra-wideband of 98%. To validate the simulation results, a prototype of the checkerboard surface is fabricated and measured. A good agreement between the experimental and simulation results is obtained.

A Circularly Polarized High-Gain Antenna With Low RCS Over a Wideband Using Chessboard Polarization Conversion Metasurfaces

A new approach for the gain enhancement and wideband radar cross section (RCS) reduction of an antenna based on the chessboard polarization conversion metasurfaces (CPCMs) is proposed. Compared with the previous low-RCS antennas, high gain and wideband low RCS of a circularly polarized (CP) antenna are achieved simultaneously. The proposed CPCM is the chessboard configuration of the polarization conversion metasurfaces (PCMs), which is made up of adjoining two-layer substrates with three metallic patterns. Low RCS is realized by 180° (±30°) reflection phase variations between two neighboring PCMs. Gain enhancement is achieved by employing a Fabry-Perot cavity, which is constructed by the PCM and the ground of the antenna. The antenna with CPCM operating at the

Broadband Radar Cross-Section Reduction for Microstrip Patch Antenna Based on Hybrid AMC Structures

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Wideband high-gain circularly polarized planar antenna based on polarization rotator

-band, excited by a sequentially rotated feeding network, is fabricated and measured. Simulated and measured results show that the left-hand CP gain of the antenna with CPCM is at least 3 dB higher than that of the reference antenna from 8.5 to 9.5 GHz and the monostatic RCS is effectively reduced from 6 to 14 GHz.

A Low-RCS and High-Gain Circularly Polarized Antenna With a Low Profile

Two difierent kinds of artiflcial magnetic conductors (AMCs) are used to reduce the out-of- band radar cross section (RCS) of microstrip patch antenna. The principle of this method is based on the high impedance characteristic of the AMC structures. The simulated results show that out-of-band RCS of the proposed patch antenna is much lower than that of the reference antenna over the frequency range of 5{12GHz. The in-band scattering characteristic of the microstrip patch antenna is analyzed, and two slots are cut on the patch antenna to reduce in-band RCS. Prototypes of the reference and designed antennas are manufactured and tested, and the measured and simulated results of the two antennas are in good agreement.