Design And Research Of Microstrip Phase-shifter Adopted In Electrically Adjustable Antennas

The electrically adjustable antennas as base antenna have been found wide use in the modern mobile systems, in which the phase-shifter is the key component capable of realizing the function of electrical adjustability. In the paper, the microstrip phase-shifter is investigated carefully, and emphases are put on two aspects below: (1) to devise microstrip phase-shifter of novel structure (2) to investigate the suspended T-junction existing in the microstrip phase-shifter and then to put forward relatively accurate equivalent circuit model for the T-junction.Firstly, the application background and the ideas of design of the microstrip phase-shifter are introduced. Then based on the former ideas, one novel phase-shifter schemes is posed and the scheme is implemented and optimized by utilizing the Ansoft HFSS software.Secondly, a simple and efficient equivalent circuit model for microstrip suspended T-juncion is proposed and in order to check the validness of the proposed model, we then compare the scattering parameters calculated from the model and the simulation results of Ansoft HFSS. The results show the error will grow bigger with the increase of the frequency and permittivity.At last in order to improve the accuracy and to extend the applicability of the circuit model, we go on to modify the proposed model by referring to the equivalent circuit of the planar microstrip T-junction and through repeating synthesis and comparision ,a revised equivalent circuit model is obtained. Then the revised model is optimized by running the genetic algorithm to synthesize the values of the circuit elements so that the newly proposed equivalent circuit model can be conveniently and accurately applied to the CAD design of the microwave circuits.