The objective of this thesis is to introduce novel procedures and guidelines to design bandstop microwave filters for modern terrestrial and satellite wireless communication systems. Among all available microwave filter technologies, planar structures of microstrip and substrate integrated waveguide (SIW) are chosen, due to ease of fabrication, low profile, weight and manufacturing cost. Particularly, SIW structures are more attractive because they have a better insertion loss, quality factor, and power handling capability in comparison to their microstrip counterparts, and can also be easily integrated into other planar circuitries. A comprehensive hybrid analytic-optimization method is developed to synthesize any single-band as well as multi-band bandstop coupling matrix. In this method, the location of reflection zeros (RZs) and the attenuations in stopbands can be determined in advance. Several novel single-band, dual-band, and triple-band bandstop filters are designed using regular and ridged SIW resonators, in-line coupled singlet resonators, cross-coupled resonators, and bandstop stubs. The designed filters have fractional bandwidths up to 23% . Moreover, a tunable ridged SIW bandstop resonator and a tunable CPW resonator, etched into the top plate of the SIW transmission line, are introduced. Combining these two resonators, a dual-band SIW filter is designed that permits one of its stopband to be tuned while another stopband is fixed. All introduced filters in this thesis are verified by commercial electromagnetic software, analytic investigations using Matlab codes, and measurements. / Graduate

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The purpose of this thesis is to present a mathematical model in which we describe the theoretical approximation of the elliptic filters. From this theoretical treatment, the transfer function and its magnitude, as well as its poles and zeros, were programmed in Turbo Pascal for AT&T and IBM (PC/XT/AT) personal computers and their compatibles. The program, PC-ELLIP, also calculates the element values for double terminated two-port networks. Source code is included.

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Several adaptive filters were investigated to enhance speech auditory brainstem responses (speech ABR). The objective was to shorten the long recording time currently needed by the standard coherent averaging method to obtain acceptable performance, which has limited the clinical adoption of speech ABR. Five algorithms were implemented: Wiener Filter (WF), Steepest Descent (SD), Adaptive Noise Cancellation (ANC) based on Least-Mean-Square error (LMS) and normalized LMS error (nLMS), and a multi-adaptive cascade combination of SD and LMS. The performance of the adaptive filters was assessed on speech ABR data gathered from several subjects and compared with coherent averaging using the overall Signal-to-Noise Ratio (SNR), the local SNR around the fundamental frequency and the first formant, and Mean-Square-Error (MSE) in the time and frequency domains. The adaptive filters could reduce the time needed, by at least one order of magnitude, for obtaining comparable signal quality as that obtained with coherent averaging.