Application Of Waveguided Band-gap Structure In Decoupling Of Antennas

As the rapid development of the wireless communication technology,multi-antenna arrays have been extensively developed for numerous applications.It can implement either diversity gain or spatial multiplexing scheme to eliminate the effect by multipath fading.However,minimization of the communication devices requires the space between antenna elements to be largely reduced,which enhances the mutual coupling and degrades the desired performance.Therefore,it is crucially important to figure out how to reduce the mutual coupling when compressing the antenna array.In order to investigate the above hot topic,this paper primarily studies on the mutual coupling reduction technology based on a newly-developed waveguided metamaterial(WG-MTM)embedded in two-or multi-element microstrip antenna arrays.Detailed contents are explicated as follows:1)Firstly,to better integrate with planar antennas or circuits,a novel planar band-gap type of WG-MTM structure by periodically etching complementary crossed meander lines(CCML)at the bottom of parallel metal plates is proposed.Its band-gap properties are thoroughly investigated by altering both the geometry dimension and periodicity of CCML unit cells.Besides,the band-gap property excited by plane waves with varied incident angles are also studied,verifying the stable features of the proposed structure under random incident angles.2)Secondly,a two-element microstrip patch antenna array equipped with the proposed band-gap CCML WG-MTM is accordingly designed to validate the mutual coupling reduction effect.Simulation and measurement both verify the reduction of mutual coupling between two coupled rectangular patch antennas.And the performance of mutual coupling reduction is further explored by varying the etching positions and scales of the CCML array.3)Thirdly,three-and four-element microstrip patch antenna arrays loaded with the proposed band-gap CCML WG-MTM are additionally realized,thus to verify the mutual coupling reduction effect of the proposed periodic structure on the multi-element microstrip patch antenna array.What's more,a wideband collar-shaped folded dipole antenna with operation bandwidth from 1.7 GHz to 3.6 GHz for multiband RF energy harvesting is designed.It provides a very stable radiation gain and efficiency covering the whole bandwidth,and its compact configuration is typically suitable for installing on walls or ceilings.Test results show that the proposed antenna is capable to simultaneously harvest the wireless energies from both PCS(1710-1880 MHz)and WLAN/WiMAX(2400-2700 MHz)bands,which will improve the output power in the wireless energy harvester.