PBG Study On The Technique And Its Application In Microwave Circuits

Applying the structure of photonic bandgap (PBG) in microwave and millimeter-wave field is a novel research direction. The development status of PBG structure is presented in this paper. If we apply the PBG material to normal microwave circuit, taking advantage of its frequency-selective property, we can construct the passive component such as filter and directional coupler. We also apply PBG to better component in existence like amplifier and to EMC.Two waveguides with PBG, a coplanar waveguide with PBG, and a microstrip patch antenna with PBG are presented. We simulate the structures using the FDTD method and commercial software HP HFSS (High-Frequency Structure Simulator), and get characteristic of broad-band bandpass filtering. For example, bandwidth 10.8GHZ, relative bandwidth 33.2%, extremely flat passband O.SdB, and great isolation -30dB are also presented. Some have bandstop characteristic. The TEM property of metal rectangular waveguide is realized in 40~43GHz, which is very important for the research of power-synthesis in millimeter-wave ^ the measurement of TEM cell and the generation and transmission of microwave soliton .At first, the method of the finite-difference time-domain(FDTD) is used to simulate the transmission of a bandpass source in the waveguide with PBG to investigate its time-domain transmission characteristic. Next, we combine this result with the Fourier Transform to get the frequency-domain transmission characteristic. It exhibits the valuable bandpass filtering properties. We can get better bandpass filtering properties by adjusting the size of metal sheet and the number of layers.We simulate the other structures with PBG by EM simulation software such as HFSS. We get the tendency of the change, better bandpass filtering characteristic and harmonic suppression properties, and we gain some useful conclusions.