Microwave coplanar waveguide tunable filters using RF MEMS

The objective of the thesis is to create an integrated tunable microwave bandpass filter in the coplanar waveguide (CPW) line regime. Finger patterning within the centre metal trace will provide the filtering structure and micro electro mechanical systems (MEMS) switches will provide the tuning capability.; An existing uniplanar bandpass CPW filter structure is selected. Modification of the filter is investigated using Ansoft HFSS 3D-modeling software tool to change the filtering characteristic to the desired frequency range and meet fabrication requirements. A lumped equivalent circuit of the final CPW filtering structure is created.; Two MEMS switch locations are investigated and lumped equivalent circuits for the switches are proposed. The resulting CPW filtering structure is novel in that the switches are extremely narrow in width and they are over a patterned centre conductor, providing prescribed transmission characteristics in both states.; Modeling of the CPW filter with the MEMS switches is done using both HFSS and by adding the switch equivalent circuit to the filter equivalent circuit. A bridge in the middle of the CPW filtering structure produces a 2 GHz tuning effect and a bridge placed after the filter primarily alters the reflection coefficients at a separate location.; The proposed tunable filter is fabricated using Carleton University's fabrication facilities. The measured results and HFSS theoretical results are well correlated. A 2.75 GHz shift of the notch frequency from 25 GHz to 22.25 GHz with insertion loss of 25 dB and 21.75 dB respectively is measured when actuating one of the bridges.