Research On Microwave Devices Based On Corrugated Substrate Integrated Waveguide

Substrate integrated waveguide(SIW)has been widely used in wireless communication systems due to its advantages of low loss,high Q value,low cost,and planarization.However,due to the presence of metallic via holes,not only does the machining process become complex,but also requires a complex DC bias network when loading active devices.As an extended research of SIW,the corrugated substrate integrated waveguide(CSIW)uses uses a group of quarter wavelength microstrip open-circuit stubs to substitute the metallic vias and form an equivalent electric wall to confine the electromagnetic wave in the waveguide.Since the independent top and bottom metal layers of CSIW,the input and output ports can be isolated from the ground to facilitate integration with active devices.In order to meet the development needs of miniaturization,the size of CSIW has been reduced in half,forming a half mode corrugated substrate integrated waveguide(HMCSIW).Its longitudinal open edge has a natural advantage that can be directly integrated with active devices.This thesis first designs a reconfigurable filter with common mode suppression based on the HMCSIW differential transmission line.The filter consists of three metal layers,with the structure and size of the upper and lower metal layers being identical.A pair of open branches are connected in parallel on the longitudinal open edge of the HMCSIW,and a double complementary split ring resonator(DBCSRR)is etched on the HMCSIW to form a bandpass filter.Then,a PIN diode is loaded onto the open circuit branch,and the length of the connected open circuit branch is controlled by controlling the on/off of the PIN diode,causing the low-frequency zero point to shift 1.1 GHz,achieving the reconfigurability of the filter.Within the passband frequency range,the common mode suppression of this filter is lower than-40 d B,indicating good common mode suppression characteristics.Secondly,a coupler with reconfigurable coupling coefficient was designed based on HMCSIW.Load several PIN diodes between two parallel HMCSIWs with opposite open edges,and change the coupling strength between the two HMCSIWs by controlling the on-off of the PIN diodes through bias voltage,thereby changing the coupling coefficient.It is possible to switch multiple coupling coefficients without changing the size of the coupler.Finally,within the frequency range of 10.9 GHz to 12.1 GHz,the reflection coefficient S11 and isolation coefficient S41 are both less than-15 d B,the phase difference is within the range of 87.5°± 2.5°,and the coupling coefficient can be flexibly switched between 14 d B,10 d B,7.5 d B,6 d B,4.5 d B,and 3.5 d B.Finally,a broadband reconfigurable filter was designed based on CSIW.A broadband filter is composed of the inherent cut-off frequency of CSIW and the high-frequency zero point generated by etching deformation DBCSRR on the top metal of CSIW.Then,a PIN diode is used to replace the opening of the inner ring in DBCSRR,and the resonant frequency of DBCSRR can be adjusted by controlling the on-off of the PIN diode,causing the high-frequency zero point to shift by 1.3 GHz,thereby achieving the reconfigurable broadband filter.