Abstract
Since antennas are strong radar targets, their radar cross section (RCS) reduction and radiation enhancement is of utmost necessity, particularly for stealth platforms. This work proposes the design of a Fabry–Perot Cavity (FPC) antenna which has wideband low monostatic RCS. While in the transmission mode, not only is gain enhancement achieved, but radiation beam is also deflected in the elevation plane. Moreover, the design is low-profile, i.e., the cavity height is ~λ/4. A patch antenna designed at 6 GHz serves as the excitation source of the cavity constructed between the metallic ground plane and superstrate. The superstrate structure is formed with absorptive frequency selective surface (AFSS) in conjunction with dual-sided partially reflective surface (PRS). Resistor loaded metallic rings serve as the AFSS, while PRS is constructed from inductive gradated mesh structure on one side to realize phase gradient for beam deflection; the other side has fixed capacitive elements. Results show that wideband RCS reduction was achieved from 4–16 GHz, with average RCS reduction of about 8.5 dB over the reference patch antenna. Off-broadside peak radiation at −38° was achieved, with gain approaching ~9.4 dB. Simulation and measurement results are presented.
Highlights
Stealth platforms have low radar cross section (RCS), but their radar signature increases significantly when antennas are mounted on them for communication purposes [1,2].This can compromise their ability to counter the radar waves, so, in this regard, design and development of low RCS antennas is deemed necessary, for safety and security.Reduction of the antenna’s RCS is a critical feat, and several methods have been investigated to ensure that the antenna radiation properties are least affected while attempting to reduce its RCS
The other method is based on periodic structures, and this includes the use of radar absorbing materials (RAMs) [8,9,10], frequency selective surface (FSS) ground plane [11,12], FSS radome [13,14], electromagnetic bandgap (EBG) structures [15,16,17], artificial magnetic conductors (AMCs) [18], perfect metamaterial absorbers (MAs) [19,20,21,22], and polarization conversion metasurfaces (PCMs) [23,24]
Our aim in this work is to develop a superstrate structure that consists of phase gradient metasurface (PGM) conjoined with an absorptive frequency selective surface (AFSS), such that the wideband monostatic RCS reduction and peak gain enhancement can be achieved for a patch antenna, and the peak radiation can be steered in a fixed angle, which becomes an additional antenna functionality in comparison to the works done previously
Summary
Stealth platforms have low radar cross section (RCS), but their radar signature increases significantly when antennas are mounted on them for communication purposes [1,2]. To improve the antenna radiation properties in parallel with lowering the RCS, further research has led to using partially reflecting surfaces (PRSs) in a Fabry–Perot Cavity (FPC) configuration, as evident in [25,26,27,28] In all of these works, backscatter reduction was achieved, and broadside antenna gain was enhanced. Our aim in this work is to develop a superstrate structure that consists of phase gradient metasurface (PGM) conjoined with an AFSS, such that the wideband monostatic RCS reduction and peak gain enhancement can be achieved for a patch antenna, and the peak radiation can be steered in a fixed angle, which becomes an additional antenna functionality in comparison to the works done previously. The antenna can be utilized for any military communication application where fix tilt-angled communication is required [34]
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