The thesis reports a compact tunable ultra-wideband (UWB) notch filter using hybrid microstrip and coplanar waveguide (CPW) structure. The tunable notch is implemented to filter out the wireless local area network (WLAN) channels from 5GHz to 6GHz. The proposed structure utilizes the resonance of open ended stubs to achieve transmission zeroes in the filter passband. Varactors and by-pass capacitors are then introduced for dynamic tunability of notch. Further, the electromagnetic decoupling of the two resonators leads to tunable bandwidth of notch. DC bias circuitry is implemented to control the varactor capacitances. Rejection levels up to 25 dB are attained using this technique while maintaining insertion loss levels below 2.5 dB in the passband. The reconfigurability of bandwidth is shown by maintaining a constant bandwidth of 150 MHz across the WLAN band for the notch. The filter achieves an excellent wide bandwidth (from 2.5 GHz to 8.5 GHz) using multimode-resonator (MMR) based topology which makes the filter one wavelength long at the central frequency.

The dissertation details several new filter and filtering antenna topologies. For filters, the novelties introduced include a microstrip version of M�bius loop res- onator based filter, a packaged dual-band filter constituted by novel dual-mode and dual-resonance substrate integrated waveguide (SIW) cavities and a method- ology for integration of planar resonators with SIW cavities in lieu of compact filtering structures. For the filtering antennas, flexible transmission zeroes (TZs) are introduced using source-load coupling, followed by the first single-layer SIW dual-band filtering antenna with orthogonal polarizations in the two bands. A methodology for synthesizing filtering antennas using coupling matrix synthesis is introduced. Also is shown a method of using multi-band filtering antennas to break the conventional limit of maximum possible n TZs from a n resonator filter. Finally, an on-chip resonant terahertz antenna with reasonable gain and bandwidth is reported.