| Modern phase array systems require a large number of expensive phaseshifters. Therefore, low loss and low cost microwave phase shifters are required to improve performance and reduce the cost of phase arrays to ensure widespread application. Ba Sr TiO (BST) thin films have been investigated as a potential low cost voltage tunable element for microwave circuit applications because of their high tunability, relatively low loss, and fast switching speed. Several groups have implemented phase shifters using BST thin films. Through analyzing the design theory of previously designed phase shifter and researching the machining technique of the device, we have improved the dielectric phase shifter. Considering characteristic of the device, we make use of hign-frequency electromagnetic emulators, ANSOFT HFSS9.0 and ADS, to study the rule about the structure parameters how to affect the insertion loss and phase shift of the device. During the course of this research, the focuses are put on the followings:(1) We analyze ferroelectric phaseshifters coupled mirotrip devices theoretically , then design one kind of these phaseshifters , including simulation process with the help of hign-frequency electromagnetic emulators. Phase shifit for this room temperature ferroelectric phase shifter is 200 degree.(2) On the base of the electromagnetic theories, we study a CPW-type ferro -electric thin film dielectric phaseshifter. A solution is set to predigest the emulation method creatively by this way: part of the circuit is changed for the equivalent value of lumped parameters. We can get the same result while use less time.(3) We analyze the equivalent circuit of BST Phase Shifter, do research about how to load BST capacitance, and program via Matlab to carry out an optimizing method of the BST phase shifter circuit. A new type of circuit structure has been proposed to implement better characteristics than traditional BST Phase Shifters. Based on the fabrication, wu drew the layout by LEDIT. |
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