In this thesis, the reconfigurable microwave bandpass filter using microstrip and slotline structure is studied with focus on the reconfigurable bandwidth and notch. Some reconfigurable notch and bandwidth filter, including a multi-notch filter which can be used in multi-bit RFID chipless tag are introduced in thesis. An ultra-wideband bandpass filter with reconfigurable single notch is designed with a short-ended stubs on slotline. This filter exhibits 5 poles and one controllable zero, while the zero can be controlled by the length of slotline stub. The zero of prototype reconfigurable range is ranged from 4.3 to 5.8 GHz when the center frequency is located at 6.75 GHz with constant bandwidth of 8.3 GHz. Besides, multi-bit chipless RFID tags are presented based on microstrip and slotline cross-shaped structure. These structures can be studied as 2-bit and 4-bit chipless RFID tag. By using RO6010 (r = 10.8, h = 0.635 mm) substrate, tags have been fabricated and measurement results verified theoretical analysis and simulation results. Finally, an ultra-wideband bandpass filter with reconfigurable bandwidth is presented, based on the microstrip and slotline structure. By using two short-ended stubs on slotline side, the proposed filter can be achieved two controllable zeros. These transmission zeros can be used to tune bandwidth by adjusting the length of slotline stubs. In experiment, we used PIN-diodes on slotline to realize the physical length control, and it has also compact size and much simple structure compared with 2 others work. The experimented results show that the bandwidth can be tuned from 2 GHz to 3 GHz realizing 1 GHz absolute bandwidth tuning range.