Studies Of Patch Antennas Based On Media-type Photonic Crystal Structure

Photonic crystals and photonic bandgap(PBG) structures have attracted extremely interests since the concept came into being in the end of 1980s. They are composed of periodic dielectric or metal materials,and the surface waves have band-gap at some ranges of frequency.The research of PBG structures in microwave region progresses rapidly because of the characteristics of frequency bandgap.In this paper,we use the theoretical analysis together with the experimental method to investigate the PBG structure thoroughly,and on the basis,the new antennas of high-gain and easy-produced are designed.In this paper,Patch antennas with Media-type PBG substrates have been studied thoroughly.A patch antenna with Media-type PBG is designed by digging air holes in the substrate.We also design a patch antenna with heterosrtucutres PBG structures,a patch antenna with crossed heterosrtucutres PBG structures,and so do the conventional patch antenna. The finite-difference time-domain(FDTD) method together with the perfectly matched layer(PML) boundary treatment has been used to simulate the four antennas.The results show that the characteristics of the three former patch antenna with PBG structure in this paper have many improvements comparing with the general ones,the main improvements is as follows:1.Comparing the gains of four patch antennas,we find the gain of the conventional patch antenna without photonic crystal is low,but the gains of three other antennas with PBG structure are adding obviously.In particular,the gain of antenna by introducing heterostrucutres PBG structure substantially improves,and the gain of crossed heterostrucutres PBG structure has reached above 14dB.2.By analyzing the return losses(S11) of the antennas,the patch antennas with PBG have a lower return losses of about -30dB,compared with -14.2dB of the conventional patch antenna.3.The reduction of return losses means that the bandwidth is increased, which is proved by the results of three new antennas with PBG.Among the three new antennas,the bandwidth of antenna with heterostructure PBG structure is improved mostly,and twices more than the bandwidth of another two new antennas.4.The resonant frequency of the antenna with PBG structures has shifted,because the equivalent length of the electromagnetic waves is increased,so the frequency declines.