A Checkerboard Metasurface for Ultra-wideband Radar Cross Section Reduction
Huan He, Jianxun Su, Zengrui Li
Information Engineering School
Communication University of China, CUC
Beijing, China
e-mail: sujianxun_jlgx @163.com
Abstract—In this paper, a checkerboard metasurface is
designed and characterized for ultra-wideband radar cross
section (RCS) reduction. The metasurface is formed of two
kinds of elements with different configuration. By
appropriately selecting the sizes of basic unit cells which based
on minkowski ring patch and square ring patch respectively, a
180°±37° reflection phase difference between two unit cells is
obtained over 8.1-22.7 GHz (94.8% bandwidth). The
metasurface based on the two unit cells is capable of altering
the direction of the fields scattered by a target to four main
directions deviating from normal direction, resulting in an
ultra-wide frequency band RCS reduction. The 7.5 dB RCS
reduction is obtained over 8.6 GHz-22.9 GHz (94.5%
bandwidth) by comparing to an equal-sized perfect electric
conductor (PEC) surface. Full-wave simulations of monostatic
RCSs of the metasurface and the equal-sized PEC surface
verify the characteristic.
Keywords-RCS reduction; metasurface; phase difference
I. INTRODUCTION
There are a plethora of researches aiming at realizing the
stealth of targets such as airborne vehicles by manipulating
and controlling electromagnetic waves in recent years. The
metasurface [1], a new class of metamaterials with
extraordinary physical properties that are not possessed by
natural materials, is capable of generating abrupt interfacial
phase changes and providing a unique approach of
controlling the reflected and transmitted wave. Because of its
low profile, low mass and potential ability of controlling
scattering electromagnetic waves, the metasurface is widely
used in many fields such as polarization converter [2],
ultrathin metalenses [3], [4], low scattering [5]-[7], wave
plates for generating vortex beams [8], [9] and
electromagnetic interference and shielding [10].
In order to reduce the monostatic RCS of a structure,
there are different methods usually introduced. One method
is devising the well-known radar absorbing metamaterials
(RAMs) to the surface of objects, which is capable of
transforming electromagnetic energy into heat [11]. However,
the disadvantage is that the frequency band of the absorbing
material is very narrow, only in the vicinity of the resonance
frequency. Another way is applying the phase cancellation or
destructive interference, which can redirect the scattering
energy to many directions away from the source direction.
The basic mechanism of the phase cancellation is the 180° ±
37° phase difference between different meta-atoms. In recent
years, many researches are based on planar metasurface. For
example, PEC and artificial magnetic conductor (AMC) are
employed to construct metasurface. And the 180° phase
difference can result in the cancellation effects [12].
However, the bandwidth is really limited since broadband
AMC structures are hard to design and implement. Then, a
checkerboard construction is proposed which consists of two
different AMC cells based on Jerusalem Cross configuration
[13]. It obtains 10 dB RCS reduction over 41% frequency
bandwidth. Likewise, a hexagonal checkerboard surface of
periodic arrangement is proposed, with the -10 dB RCS
reduction bandwidth of about 61% [14]. For ultra-wideband
characteristic, saltire arrow and four-E-shaped unit cells are
used in the design [12]. The metasurface obtains a broad
bandwidth of 85% for 10 dB RCS reduction. The reduction
is caused by the 180° phase difference between adjoining
two square configurations. Another method is to utilize the
polarization conversion metasurface to realize wideband
RCS reduction. In this case, the metasurface is composed of
a square and L-shaped patches, which can convert the
polarization of the incident wave to its cross-polarized
direction, representing the plasmon cloaking of an object
[15]. A -10 dB RCS reduction is achieved over an ultra-
wideband of 98%. Furthermore, the multi-resonance method
is also employed in [16]. The metasurface consisting of four
subarrays randomly distributed reflection phases at four
specific frequencies achieves 52.63% bandwidth for -10 dB
RCS reduction.
The goal of this paper is to design a checkerboard
metasurface for ultra-wideband RCS reduction. Two unit
cells with 180°±37° phase difference in ultra-wide frequency
band are exactly designed to build the metasurface, resulting
in ultra-wideband phase cancellation. The proposed
metasurface has the scattering pattern of four strong lobes
away from the source direction. The RCS reduction by more
than 7.5 dB over 8.2 GHz - 22.9 GHz is obtained. And the
bistatic RCS is effectively suppressed in ultra-broadband
frequency band.
The rest of the letter is organized as follows. Section II
introduces the design of unit cells and the metasurface for
ultra-wideband RCS reduction. Section III shows the
simulated results of the proposed metasurface. Finally, this
work finalizes with the conclusions in Section IV.
II. S
TRUCTURE DESIGN
A. Unit Cell Design
The basic unit cell of the presented metasurface is
composed of two metallic layers separated by a substrate
with dielectric constant of 2.65 and thickness of 3 mm. The
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2017 17th IEEE International Conference on Communication Technology
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