Abstract
In this paper we designed and fabricated a metasurface working as a radar cross section (RCS) reducer over an ultra wide band of frequency from 3.8 to 10.7 GHz. The designed metasurface is a chessboard-like surface made of alternating tiles, with each tile composed of identical unit cells. We develop a novel, simple, highly robust and fully automated approach for designing the unit cells. First, a topology optimization algorithm is used to engineer the shape of the two unit cells. The area of each unit cell is pixelated. A particle swarm optimization algorithm is applied wherein each pixel corresponds to a bit having a binary value of 1 or 0 indicating metallization or no metallization. With the objective of reducing the RCS over a specified frequency range, the optimization algorithm is then linked to a full wave three-dimensional electromagnetic simulator. To validate the design procedure, a surface was designed, fabricated and experimentally tested showing significantly enhanced performance than previous works. Additionally, angular analysis is also presented showing good stability and wide-angle behavior of the designed RCS reducer. The automated design procedure has a wide range of applications and can be easily extended to design surfaces for antennas, energy harvesters, noise mitigation in electronic circuit boards amongst others.
Highlights
In stealth technology, a key objective is to reduce the radar cross section (RCS) of metallic objects such as missile and aircrafts
Applying metasurfaces has been proposed as an effective technique for redirecting the scattered field by using a chessboard-like surface composed of artificial magnetic conductor (AMC) and perfect electric conductor (PEC) cells as a covering layer of a metallic object[23]
The comparison between the 10 dB RCS reduction bandwidth and the fractional bandwidth clearly shows that our optimized design approach considerably enhanced the operating bandwidth
Summary
A key objective is to reduce the radar cross section (RCS) of metallic objects such as missile and aircrafts. Due to in-phase and out-of-phase reflections from adjacent PEC and AMC cells, the scattered fields are altered and the energy is redirected without changing the shape of the underlying object The advantage of this technique is that the covering structure is thin, low profile and low cost; the RCS reduction occurs over a very narrow bandwidth of approximately 5%23. To overcome this problem, a chessboard-like configuration formed by combining two AMC cells (as shown in Fig. 1) has been proposed, designed and fabricated[24,25,26]. This approximation allow for efficient simulation by using a periodic boundary condition (PBC) applied only on one unite cell
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