High-power Miniaturized X-band Waveguide Phase Shifters With Low Insertion Loss

Phase shifters are requisite devices for phase-array radar system,microwave communication system,high-power microwave system etc,used as beam pointing&controlling and beam forming module.With the development of the application of high-power microwave,phase-array radar and others,higher requirements are put forward to the phase shifter,such as high power capacity,low insertion loss and miniaturized sizes.This thesis focuses on researching the high power capacity low insertion loss waveguide phase shifter and the low insertion loss miniaturization waveguide phase shifter for X-band.At first,according to the basic theory of loaded phase shifter,a PIN diode loaded waveguide phase-shifting structure with high power capacity and low insertion loss is proposed.The basic structure of the phase shifter includes:(1)a metal waveguide with a slot on the wide wall,(2)a double-branch conductor line on the slot,(3)two high-power PIN diodes(such as silicon carbide diodes)for connecting the conductor line to the waveguide wall,(4)related bias circuit for PIN diodes.Phase shifting is achieved by controlling the bias voltage of the two PIN diodes thus changing the capacitance value.The results demonstrate that the insertion loss of the phase-shifting structure is lower,and the return loss of the phase-shift structure is smaller than similar waveguide phase shifters.The theoretical peak-power capacity is of the level of MWs.Secondly,based on a Y-junction ferrite circulator using large line-width of the k-th spin wave,a ferrite-circulator switch with high power capacity and low insertion loss is designed.The DC magnetic bias circuit is placed outside the Y-junction.Furthermore,a novel 180° waveguide phase shifter with high power capacity and low-insertion loss is designed and fabricated,consisting of the ferrite-circulator switches and U-shaped waveguides(or slow-wave waveguides).The measurement results are in good agreement with the simulation results under low power condition.Finally,combining the two of such phase shifters,a four-bit waveguide 360° phase shifter with high power capacity and low insertion loss is designed.The power capacity of the phase shifter is higher(1.2 MW),and the insertion loss is smaller(0.2 dB)compared to its counterparts.According to the theory of loaded phase shifter,a small-angle waveguide phase-shifting structure is realized by loading L-shaped conductor lines symmetrically.These L-shaped lines are then loaded on a double-ridge waveguide along the longitudinal direction with different spacing.At the same time,a miniaturized phase shifter with large-angle phase shift is presented by loading ring-shaped conductor lines in the double-ridge waveguide.The phase shift is realized by controlling the"open-loop" and "closed-loop" states of the conductor rings via switches.In this manner,a 0°?180° phase shifter with low insertion loss and miniaturized size is designed.The results demonstrate that the insertion loss of the phase shifter is small,and the size of the phase shifter is expressively reduced.