The central theme of this work is the design of compact microstrip bandpass filters and diplexers and the investigation of applications of these circuits in integrated transceiver RF front-end. The core of this thesis therefore presents the following stages of the work:
- Analysis of coupled pseudo-interdigital resonators and lines; formulation of
approximate transmission zero conditions and the investigation of coupling
between these two resonators and related structures.
- Development of compact, low loss and high selectivity microstrip pseudointerdigital bandpass filters. The design procedure of the filter consists of three
simple steps, starting from the design of a parallel-coupled bandpass filter using the image parameter method applied to coupled microstrip lines. The development
of compact microstrip diplexers composed of these filters uses the optimized
common-transformer diplexing technique. An experimental verification of the
developed filters and diplexers is made.
- Investigation of the use of stepped impedance resonators (SIR) for the design of pseudo-interdigital bandpass filters with advanced characteristics. The design of compact dual-band filter using SIR. The investigation of possible improvement of the stopband of bandpass filters using bandstop generating structures. The
application of SIR, defected ground structures (DGS), spur-lines, and opencircuited stubs in the design of compact bandpass filters with improved stopband.
- The application of the proposed filters and diplexers in the design of integrated antenna filters and antenna diplexers. Improvement of performance of patch
antennas, such as suppression of spurious harmonics of single-band antenna and
improvement of bandwidth and selectivity of dual-band antenna, as a result of
integration with filters. Separation of antennas’ bands and reduction of component count in integrated antenna diplexers