Research Of Power Divider Based On Photonic Bandgap Structure

Photonic Bandgap (PBG) Structure is a kind of periodic structure which has some special characteristics, such as bandstop, slow wave, and high effective characteristic impedance. Defected Ground Structure (DGS) is a non-periodic microwave structure which is extended from PBG structure. It can prohibit the propagation of electromagnetic waves within a certain band of frequencies. Just like PBG structure, it also has bandstop. Photonic Bandgap has been paid great attention by microwave fields since the introducing of its concept in 1980s. It has been used widely for design of antennas and microwave circuits such as filter, power divider and so on.This paper mainly studied PBG structure's application in microwave circuits. And finite-difference time-domain (FDTD) method is applied in the research of photonic crystals' transmission characteristic. The effect of the structure parameters on 2-D PBG is analyzed. And square, circle slots with different dimensions are investigated on the design of microstrip power divider. The simulation and comparison are made on it. Furthermore, a novel power divider with DGS structure is studied. Non-periodic dumbbells are eroded on the metal ground. Compared with periodic PBG structure, DGS is simpler in structure, smaller in dimension and lower in insertion loss.First, the theory of power divider designing is discussed in this paper. The power dividers with structure of PBG and DGS are calculated with FDTD method, through witch we will obtain the electromagnetic waves propagated in the time-domain. Then the frequency characteristic can compute by Fourier transform. The effects of various kinds of shapes and their dimensions of PBG and DGS on frequency characteristic of the circuits are studied. After the disciplines are summed up, some new structures of DGS are provided. Technique of the perfectly matched layer is used for the absorption conditions in FDTD. Then the designing parameters are simulated and optimized by high frequency electromagnetism simulating software ADS. At last, a power divider with PBG structure is fabricated and tested by VNA. Compared with calculating and simulating results, it is basically accordant.