Dual-band slot antenna using CPW feed line and metasurface

A dual-band antenna designed by combining a coplanar-waveguide-fed (CPW) slot antenna with a metasurface is presented in this paper. The CPW-fed antenna printed on one side the substrate is used as the source antenna. The metasurface consisting of 16 unit cells in a 4 £ 4 arrangement is printed on the other side of the substrate. Two operating bands at around 3.4GHz and 5GHz are generated, with the radiation patterns pointing at mainly opposite directions. 1. INTRODUCTION Slot antenna with coplanar-waveguide (CPW) fed is increasingly popular because of the simple structure (1{3). Moreover, more than one slot of difierent sizes can be easily integrated with the CPW feed line at the same time, so it is widely used for design of multi-band antennas. However, the disadvantages of such antennas are also obvious, one of which is bi-/multi-directional radiation pattern, this could be a problem especially when only one direction is desired. In addition, multi- directional radiation also leads to relatively low gain because of power decentralization. Metasurface, a two-dimensional equivalent of metamaterial, has been attracting attention for researchers in recent years (4,5). Due to its planar structure, metasurface can be easily combined with planar antenna to achieve performance enhancement in terms of bandwidth, gain and radia- tion pattern. In such application, the original planar antenna is called the source antenna. When the source antenna is combined together with a metasurface, it is called a metasurfaced antenna (4). Among the reported metasurfaced antennas studied (3{7), the metasurfaces and source antennas were fabricated on difierent dielectric substrates and placed at a certain distance away from each other. Although the distance between source antenna and metasurface was very close, the thickness of metasurfaced antenna has been increased considerably compared to source antenna. In addition, the complexity of antenna was also increased due to assembly problem. However, this will be dif- ferent if a CPW feed line is used, if we place the metasurface on the other side, the metasurface and source antenna will be combined perfectly as one single antenna, the thickness of the metasurfaced antenna does not even change at all compared to that of the source antenna. Previous studies have shown that adding a metasurface to source antenna will produce two main results: 1) creating new resonant frequency bands and 2) changing the radiation patterns (4,6). The former result can be used to design antennas with dual-/multi-bands, while the latter result can be used to manipulate the radiation patterns. If we can achieve these two results together, we can have new frequency bands with difierent radiation patterns. In this paper, a metasurface consists of a simple CPW-fed slot antenna and a metasurface is proposed to generate two frequency bands. The CPW-fed slot antenna is printed on one side of the substrate, while the metasurface is printed on the other side. This arrangement is difierent from others where difierent substrates are used for the antenna and metasurface. Computer simu- lation shows that our proposed design can generate two operating frequency bands. Moreover, the radiation patterns in these frequency bands are at opposite directions. However, it is yet to flnd applications for the proosed design.