Planar, wide-band omnidirectional retroreflector using metal-only transmitarray structure for TE and TM polarizations

Abstract

In this paper, a novel planar and wideband metal-only retroreflector is proposed that efficiently reflects the obliquely incident electromagnetic wave along its incident direction in omnidirectional angle range. The means of omnidirectional is the capability of retroreflectivity in all azimuth angles $$(\varphi_{i} )$$ ( φ i ) and in a wide elevation angle $$(\theta_{i} )$$ ( θ i ) range. The proposed structure consists of a symmetrical transmitarray structure with beam scanning capability in which a metal plate is placed instead of the feed. The transmitarray is designed by using the generalized multifocal approach in which the beam scanning capability is possible via feed displacement and the phase of the elements has azimuthal symmetry that causes omnidirectional property. Now by placing a metal plate at the location of feed displacement and provided that the focused waves are nearly perpendicular to the metal plate, the plane wave is reflected back along its incident direction i.e. the retroreflectivity property is obtained. The proposed retroreflector simulated by CST STUDIO software and fabricated with laser cut technology. The results of measurement show an omnidirectional retroreflectivity with half-power (3-dB RCS level) elevation field of view of 60° (− 30° to 30°) in the frequency range of 8.5–10 GHz (approximately 17%) for both TE and TM polarization.

Wideband/Wide-Angle Planar Single-Layer Retroreflector Using Double Gradient Metasurfaces

“…This plot illustrates the RCS enhancement around the designed incident angle at all three frequencies. To provide a comprehensive understanding of the characteristics of our work, a comparison between our proposed retroreflector and references [8,15,16,17,18,19] is presented in Table 3. It can be observed that while our proposed retroreflector exhibits a higher maximum ripple in the monostatic RCS, it is a single-layer structure with a very small total thickness.…”

“…They proposed a planar monolithic near-infrared retroreflector composed of two layers of silicon nanoposts, which, following the cat's eye theory, reflects light along its incident direction with a normal incidence efficiency of 78% and a large half-power field of view of 60°. Then this method was subsequently implemented in the field of acoustics [16] and microwave [17][18][19]. From the works conducted so far in the field of retroreflectivity using metasurfaces, it can be concluded that single-layer metasurfaces with low thickness have only been utilized for single-angle or discrete multiple-angle retroreflection.…”