Dual-layer Flexible EBG Structure for Broadband and High Gain Antenna Design

This paper presents a broadband, high gain antenna design consisting of a combination of flexible dual-layer electromagnetic band-gap (EBG) material and a conventional microstrip patch antenna. The frequency dependent reflection and transmission characteristics of the two EBG layers are used to enhance the impedance bandwidth and the realized gain of the antenna. Simulation results show that a 3 dB increase in antenna gain in-crease (from 7.35 dBi to 10.4 dBi) can be achieved with the flexible dual-layer EBG superstrate applied at target frequency of 3.4 GHz. A noticeable increase in impedance bandwidth can also be observed. Furthermore, simulations in bending conditions demonstrate that the performance of the proposed structure remains stable with the deformation and hence is suitable for application required flexible textiles. In cases where a compact design is desired, the proposed structure allows the antenna metal ground plane size to be reduced to 72% of its original size while maintaining a relatively stable gain, without necessarily requiring a large ground plane comparable to the EBG structure. Another advantage is that the dual-layer EBG structure can achieve an increase in both gain and bandwidth for single linearly polarized antennas. This study illustrates the performance enhancement and effectiveness of applying flexible EBG superstrated to form broadband and high gain antenna.