Extended Path Filter Configurations

International audienceIn this work we introduce a method for increasing the maximum number of transmission zeros in the response of path filters. This recently introduced inline filter configuration allows for up to four transmission zeros on the imaginary axis. The solution proposed in this work, while maintaining the inline configuration, increases the number of transmission zeros up to N-1 (with N order of the filter). The novel concept allowing the additional zeros introduction is verified by means of the design of a waveguide filter of order 8 with 6 transmission zeros

Path Filters: A Class Of True In-Line Topologies With Transmission Zeros

International audienceIn this paper we present a comprehensive discussion of a new class of inline microwave filters with transmission zeros in the response, namely the path filters. The main features of this filters class are highlighted, and an original (synthesis-based) design approach is presented, relying on the derivation of suitable characteristic polynomials. In addition to the classical Generalized Chebyshev characteristic, two new characteristics are introduced (namely the Bounded Chebyshev and the Reduced Chebyshev), that allow improving the flexibility in the requirements assignment of path filters. A new method for the synthesis of the lowpass prototype is also introduced, that overcome the limitation in the classical synthesis based on the manipulation of the transversal prototype (whose synthesis may fail in case of path filters). Finally, the proposed approach for designing the class of considered filters has been validated by several examples that include the evaluation of the characteristic polynomials, the prototype synthesis and the dimensioning of the physical structures in waveguide technology

A Novel Coupling Structure for Inline Realization of Cross-Coupled Rectangular Waveguide Filters

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A True Inline Coaxial-Cavity Filter with Two Symmetric Zeros

This article has been presented at IEEE MTT-S International Microwave Symposium (IMS 2020), Atlanta, GA, USA, June 6–11, 2021.International audienceThis work deals with the design of true inline filters with two symmetric transmission zeros. A new filters category named "path filters" is introduced (including the considered filters), his general features are discussed and analyzed and a general method for the synthesis of the low-pass prototype network is proposed. To validate the proposed design approach, a coaxial-cavity filter with a true inline topology exhibiting two symmetrical transmission zeros has been designed and fabricated. The realized prototype shows a response in good agreement with the theory

Emerging Trends in Techniques and Technology as Applied to Filter Design

In the last decade, the filter community has innovated both design techniques and the technology used for practical implementation. In design, the philosophy has become "if you can't avoid it, use it", a very practical engineering approach. Modes previously deemed spurious are intentionally used to create in-line networks incorporating real or imaginary transmission zeros and also reduce the number of components and thus further miniaturize; spurious responses are re-routed to increase the passband width or stopband width, frequency variation in couplings is used to create complex transfer functions, with all of these developments using what was previously avoided. Clever implementations of baluns into passive and active networks is resulting in a new generation of noise-immune filters for 5G and beyond. Finally, the use of a diakoptic approach to synthesis has appeared an evolving approach in which small blocks ("singlets", "doublets", etc.) are cascaded to implement larger networks, (reducing the need for very complex synthesis), with this new approach promising a large impact on the implementation of practical structures. Filter technology has migrated towards "observe it and then adapt it", pragmatically repurposing tools not specifically originally intended for the applications. Combinations of surface wave and bulk wave resonators with L-C networks are improving the loss characteristics of filters in the region below 2 GHz. Lightweight alloys and other materials designed for spacecraft are being used in filters intended for space, to provide temperature stability without the use of heavy alloys such as Invar. Fully-enclosed waveguide is being replaced in some cases by planar and quasiplanar structures propagating quasi-waveguide modes. This is generically referred to as SIW (Substrate Integrated Waveguide). Active filters trade noise figure for insertion loss but perhaps will offer advantage in terms of size and chip-level implementation. Finally, the era of reconfiguration might be approaching, as the basic networks are evolving, perhaps lacking only the appearance of lower-loss, higher-IP solid-state tuning elements

Passivity and Maximum Quality Factor Assessment in Lossy 2-port Transfer Functions

International audienceLossy transfer functions are appealing in the design of filters and electric networks, as they can be exactly implemented by physical passive components. However, lossy techniques relax most of the constraints governing the design and thus offer many degrees of freedom but with unclear effects on realizability. This work describes first an analytical method to check whether a given 2-port matrix transfer function is passive. Moreover, for comparison purposes, a technique to assess the maximum allowed predistortion is proposed, related to the highest required quality factor

From Academia Armena Sancti Lazari to the Establishment of Armenian Studies at Ca’ Foscari

The Armenian Studies have a very long tradition in Italy. However, the establishment of the official teaching of Armenian at Ca’ Foscari is particularly significant. It is a direct continuation of many Armenian traces present in the lagoon city for centuries, such as the birth of the first Casa Armena in Europe in 1245, the prosperous diplomatic relations between the Republic of Serenissima and the Kingdom of Armenia, the printing of the first Armenian book in 1512, the arrival of Armenian merchants from Julfa, who highly contributed to the economy of Venice, and finally the institution of the Mekhitarist Congregation of the Armenian monks on the island of San Lazzaro, recognised by Napoleon as Academia Armena Sancti Lazari. After an historical excursus, the paper will go on to detail some significant periods of Armenian Studies at Ca’ Foscari