Design methods for microwave filters and multiplexers

This thesis is concerned with developing synthesis and design procedures for microwave filters and multiplexers. The core of this thesis presents the following topics. 1) New classes of lumped lowpass prototype filters satisfying generalized Chebyshev characteristics have been investigated. Exact synthesis procedures are given using a relatively new technique termed the alternating pole synthesis technique to solve the accuracy problem. The properties of these filters and their practical advantages have been discussed. Tables of element values for commonly used specifications are included. 2) A new design procedure has been developed for bandpass channel multiplexers connected at a common junction. This procedure is for multiplexers having any number of Chebyshev channel filters, with arbitrary degrees, bandwidths and inter-channel spacings. The procedure has been modified to allow the design of multi-octave bandwidth combline channel filter multiplexers. It is shown that this procedure gives very good results for a wide variety of specifications, as demonstrated by the computer analysis of several multiplexers examples and by the experimental results. 3) A compact exact synthesis method is presented for a lumped bandpass prototype filter up to degree 30 and satisfies a generalized Chebyshev response. This prototype has been particularly utilized in designing microwave broadband combline filters. 4) Different forms of realization have been discussed and used in design and construction of different devices. This includes a new technique to realize TEM networks in coaxial structure form having equal diameter coupled circular cylindrical rods between parallel ground planes. Other forms of realization have been discussed ranging from equal diameter posts, direct coupled cavity waveguide filters to microwave integrated circuits using suspended substrate stripline structure. The experimental results are also given. In addition, the fundamentals of lumped circuits and distributed circuits have been briefly reviewed. The approximation problem was also discussed

Distributed Channel Synthesis

Two familiar notions of correlation are rediscovered as the extreme operating points for distributed synthesis of a discrete memoryless channel, in which a stochastic channel output is generated based on a compressed description of the channel input. Wyner's common information is the minimum description rate needed. However, when common randomness independent of the input is available, the necessary description rate reduces to Shannon's mutual information. This work characterizes the optimal trade-off between the amount of common randomness used and the required rate of description. We also include a number of related derivations, including the effect of limited local randomness, rate requirements for secrecy, applications to game theory, and new insights into common information duality. Our proof makes use of a soft covering lemma, known in the literature for its role in quantifying the resolvability of a channel. The direct proof (achievability) constructs a feasible joint distribution over all parts of the system using a soft covering, from which the behavior of the encoder and decoder is inferred, with no explicit reference to joint typicality or binning. Of auxiliary interest, this work also generalizes and strengthens this soft covering tool.Comment: To appear in IEEE Trans. on Information Theory (submitted Aug., 2012, accepted July, 2013), 26 pages, using IEEEtran.cl

Generic Feasibility of Perfect Reconstruction with Short FIR Filters in Multi-channel Systems

We study the feasibility of short finite impulse response (FIR) synthesis for perfect reconstruction (PR) in generic FIR filter banks. Among all PR synthesis banks, we focus on the one with the minimum filter length. For filter banks with oversampling factors of at least two, we provide prescriptions for the shortest filter length of the synthesis bank that would guarantee PR almost surely. The prescribed length is as short or shorter than the analysis filters and has an approximate inverse relationship with the oversampling factor. Our results are in form of necessary and sufficient statements that hold generically, hence only fail for elaborately-designed nongeneric examples. We provide extensive numerical verification of the theoretical results and demonstrate that the gap between the derived filter length prescriptions and the true minimum is small. The results have potential applications in synthesis FB design problems, where the analysis bank is given, and for analysis of fundamental limitations in blind signals reconstruction from data collected by unknown subsampled multi-channel systems.Comment: Manuscript submitted to IEEE Transactions on Signal Processin

On the spectral factor ambiguity of FIR energy compaction filter banks

This paper focuses on the design of signal-adapted finite-impulse response (FIR) paraunitary (PU) filter banks optimized for energy compaction (EC). The design of such filter banks has been shown in the literature to consist of the design of an optimal FIR compaction filter followed by an appropriate Karhunen-Loe/spl grave/ve transform (KLT). Despite this elegant construction, EC optimal filter banks have been shown to perform worse than common nonadapted filter banks for coding gain, contrary to intuition. Here, it is shown that this phenomenon is most likely due to the nonuniqueness of the compaction filter in terms of its spectral factors. This nonuniqueness results in a finite set of EC optimal filter banks. By choosing the spectral factor yielding the largest coding gain, it is shown that the resulting filter bank behaves more and more like the infinite-order principal components filter bank (PCFB) in terms of numerous objectives such as coding gain, multiresolution, noise reduction with zeroth-order Wiener filters in the subbands, and power minimization for discrete multitone (DMT)-type nonredundant transmultiplexers

Deciphering ryanodine receptor array operation in cardiac myocytes

Elemental calcium signals from RYR arrays operating in cardiac myocytes have been extensively characterized with ever-improving optical methods and other innovative techniques. However, the exact nature of elemental calcium signals in terms of RYR gating in situ remains an enigma. Here, we synthesize insights gleaned from recent developments in single-channel resolution of cardiac RYR organization and in visualization of calcium release events that are much smaller than calcium sparks. This synthesis leads to the proposal of a conceptual framework that promises to unify diverse observations in sparkology.PhysiologySCI(E)PubMed7EDITORIAL MATERIAL2129-13313

Alias-free, real coefficient m-band QMF banks for arbitrary m

Based on a generalized framework for alias free QMF banks, a theory is developed for the design of uniform QMF banks with real-coefficient analysis filters, such that aliasing can be completely canceled by appropriate choice of real-coefficient synthesis filters. These results are then applied for the derivation of closed-form expressions for the synthesis filters (both FIR and IIR), that ensure cancelation of aliasing for a given set of analysis filters. The results do not involve the inversion of the alias-component (AC) matrix