Based Photonic Crystals With Different Media Of The New Antenna

Based on the simulation method of finite difference time domain (FDTD) (together with the boundary treatment of an anisotropic perfect matched layer of absorbing media for the truncation of FDTD lattices) and the theory of ordinary antennas, antennas based on photonic bandgap (PBG) materials and meta-materials are studied in the present dissertation. The purpose is to develop new antennas with high directivity, easy to manufacture, and better performance in other characteristics.1. The simulation and test have been carried out for a metallic photonic bandgap (MPBG) reflector antenna, with an explicit method as well as a genetic algorithm. Then three types of MPBG resonant antennas with cavities similar to a laser's cavity are designed. They have a high directivity (reaches 60.0), a high radiation resistance (reaches 46893Ω), or have both a high directivity (reaches 30.2) and a high radiation resistance (reaches 227Ω), respectively.2. A new photonic bandgap cover has been designed. Using this cover, the directivity of the patch antenna (11.2dB) is very close to its theoretical limit (12.0dB). Its design idea, which is different from the PBG cover maintained before, is to use the defect modes of a PBG structure of finite size. It is also easier to manufacture as compared to the other PBG covers. Its effectiveness is also exhibited in the patch antenna with a perfect magnetic conductor (PMC) substrate and a PBG cover.3. A PMC structure with a complete photonic bandgap has been designed. Its size is small (with an unit length of about 23.7% of the wavelength in the cover medium), and its effectiveness is evident (the patch antenna's directivity is increased by 3.16dB). Combining this PMC structure with the PBG cover maintained above, a new patch antenna with a PMC substrate and a PBG cover has been introduced for the first time. Such a structure can increase the directivity more effectively (the directivity is increased by 7.3dB).4. A meta-material is introduced to the cover of a patch antenna for the first time. Its band structure is analyzed. After the working frequency is selected, the meta-material cover increases the patch antenna's directivity by 9.14dB. Its mechanism is completely different from that of a PBG cover. The mechanism of the meta-material cover, the number of the cover's layers, and the distance between the layers, are analyzed in detail.In the dissertation, we introduce three types of MPBG resonant antennas, the patch antenna with a new PBG cover, the patch antenna with a new PMC substrate, the patch antenna with a PMC substrate and a PBG cover, the antenna with a meta-material cover. The work is also an important supplement to the characteristic theory of a PMC structure and the theoretical model of a PBG cover. These are important for developing new antennas with a high directivity and a high workability.