Giuseppe Macchiarella

Politecnico di Milano | Polimi · Department of Electronics, Information, and Bioengineering

This paper introduces novel frequency-variant coupling (FVC) structure in rectangular waveguide. The key feature of this structure is its ability to generate two transmission zeros (TZs) and one pole, reducing by one the number of physical resonators in waveguide filters with frequency-variant coupling (FVC) presenting TZs in the response. Moreover...

A comprehensive design procedure for quasi-inline filters using strongly coupled resonator quadruplets (SCRQs) is presented in this article. Just recently proposed, the SCRQ is a novel building block structure that allows for the generation of two transmission zeros and three passband poles in the response of microwave filters. This block belongs t...

In this letter, we extend the computation procedure of the transversal coupling matrix proposed by Cameron (based on the expansion into partial fraction of the admittance matrix polynomials) to the cases where the original algorithm fails. Such cases happen when some of the admittance matrix eigenvalues are coincident or when common roots are prese...

A new structure, namely the strongly coupled resonator quadruplet (SCRQ), is presented in this article for the realization of compact pseudoelliptic evanescent mode filters. The SCRQ consists of a quadruplet of resonators, and it can be seen as the combination of a strongly coupled resonator triplet (SCRT) and a fourth resonator, the latter being e...

The coupling matrix provides an immediate tool to describe a network, widely used in the context of microwave filters. While several techniques exist to obtain and manipulate the coupling matrix for a given response, the opposite is traditionally achieved by numerically evaluating the response of the network at each frequency of interest and fittin...

This article presents a general synthesis method for achieving flexible bandwidth of a bandpass filter by cascading modular blocks. The synthesis utilizes a matrix procedure in the bandpass domain, enabling the extraction, relocation, and cascading of various bandpass blocks (including bandpass doublets, triplets, quadruplets, and boxes) together....

We present an exact synthesis procedure for the low-pass prototype of extracted-zero filters. This type of filter has been recently introduced and it allows the realization of a true inline topology with up to two transmission zeros. Compared to other inline (or quasi-inline) solutions, the one here considered is the simplest to dimension and fabri...

In this work, we analyze the behavior of TE201 waveguide singlets, proposing dimensioning criteria applicable in the portion of the single-mode bandwidth of the input waveguide comprised between $1.4f_{c}$ and $1.6f_{c}$ , where $f_{c}$ is the dominant mode cut-off frequency. We address the relationship between the physical features of the si...

In this article, we discuss the synthesis of a strictly inline filter configuration allowing the placement of up to four transmission zeros (TZs) in the frequency response. This configuration here referred to as extracted-zero (EZ) is often adopted in the practice, but the dimensioning generally resorts to empirical strategies and numerical optim...

This article provides a comprehensive discussion of the block named generalized SymBox (GSB). The analytical synthesis approach and a set of design examples are presented. Redundant couplings or redundant resonances are introduced into conventional box topology to avoid negative couplings, forming the GSB block, regardless of the position of transm...

In this article, 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...

This letter presents a practical solution to realize finite frequency transmission zeros with independent location for wideband evanescent-mode filters. The method consists of using offline resonators located at the input and/or output of the filter. In contrast with the extracted-pole technique commonly employed for narrowband filters to generate...

Lossy 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 analytic...

This paper presents a review of the recent advances in the field of substrate integrated waveguide (SIW) filters, with particular emphasis on the techniques adopted to increase the out-of-band rejection of the filters and on the miniaturization strategies. After an overview of classical approaches to introduce transmission zeros in SIW filters, a n...

A general design procedure for inline waveguide filters with frequency-variant couplings (FVCs) is presented. The goal of the design is the introduction of transmission zeros (TZs) in the filter response. The filter design starts with the synthesis of a low-pass prototype with FVC, adopting a method that recently appeared in the literature. The low...

This article presents an analytical method for the synthesis of a low-pass prototype filter constituted by cascaded ${n}$ -tuplets, including resonant node (RN) and nonresonant node (NRN). The method extends the features of previously published solutions, limited to RNs only or that allow the inclusion of NRNs but in rigid configurations. The met...

This 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 des...

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 imag...

This article discusses the synthesis of a new class of cross-coupled blocks incorporating frequency-variant couplings, that is, the frequency-variant blocks (FVBs), and their planar implementations based on an analytical approach. The proposed FVBs require fewer coupling elements with regard to traditional blocks, while can realize a quasi-canonic...

In this article, a novel design approach for a general configuration of extracted-pole filters is presented. The proposed solution is based on the synthesis of a prototype network, followed by the evaluation of universal coefficients. The prototype is then denormalized into a form suitable for the implementation that is characterized by parameters...

This letter presents an accurate model for the stubs used as frequency-dependent coupling elements in substrate integrated waveguide (SIW) filters, with the aim to generate transmission zeros (TZs) in the frequency response. The model is based on the actual modes excited in the stub, differently from the single-mode (equivalent circuit) representat...

This paper presents a new cross-coupling structure for introducing transmission zeros in waveguide filters with inline configuration. The cross-coupling is realized by an internal bypass metallic loop structure (wire), short-circuited to the filter top plate and passing through the waveguide cavities. Positive and negative cross-couplings are reali...

In this letter a new type of singlet is introduced, called stopband singlet. The new singlet is implemented in rectangular waveguide, exploiting TE₃₀₁ as resonating mode and TE₁₀ mode as nonresonating bypass coupling. Unlike the previously introduced singlets [which produce one transmission zero (TZ) and one reflection zero (RZ)], the stopband sing...

In "Recipe for Cooking Microwave Filters," we show the classic recipe for "cooking" with narrow-or moderate-bandwidth microwave filters.While the result of this recipe is generally effective [1] (the "cake" is only rarely not edible), the tendency of some "cooks" (often young microwave engineers) is to jump to the last two steps as quickly as possi...

In this article, we introduce a synthesis-based design approach for waveguide filters, including singlets. As is known, a singlet block comprises one resonator coupled to source and load plus an additional coupling between source and load. In this way, a pole-zero pair is produced, thus allowing the introduction of a transmission zero in the freque...

In this paper, we propose the design of two perfect multilayered linear transpolarization structures working in transmission. These linear polarization converters are capable to rotate the polarization 90° independently from the direction of the input linear polarization. Results show an excellent conversion ratio.

In this paper, a direct synthesis approach is presented to realize high selectivity in-line topology filters with adjacent frequency-variant couplings (FVCs). By considering the annihilation of frequency-variant elements during admittance matrix transformation for the first time, this work provides a deterministic mechanism (no optimization is invo...

This paper presents a complete design procedure for in-line evanescent mode filters using an innovative pseudoelliptic structure, namely, the strongly coupled resonator triplet (SCRT). The SCRT can be seen as the combination of a strongly coupled resonator pair (SCRP) and a third resonator next to the pair. Compared to the SCRP, which at the passba...

This paper presents an original synthesis-based approach for the complete design procedure of pseudoelliptic in-line filters using strongly-coupled resonators pairs (SCRPs). The proposed synthesis method is based on the derivation of the coupling matrix of a new basic building block that we called SymBox. This new topology is composed of four reson...

A direct matrix approach is presented for the first time to synthesize high selectivity in-line topology filters where multiple transmission zeros are generated and independently controlled by a set of frequency-variant couplings. As the resultant network only involves resonators cascaded one by one without any auxiliary elements (such as cross-cou...

This paper presents a novel synthesis technique for coupled-resonator filters with frequency-dependent couplings. Unlike the works so far appeared in the literature, the proposed technique is not based on the optimization of a network with assigned topology, but it consists in the explicit synthesis of a folded prototype with frequency-dependent tr...

In this paper, a direct synthesis approach is proposed for designing a Chebyshev filter that matches the frequency variant complex loads at both the ports. The approach is based on the power wave renormalization theory and two practical assumptions: 1) the prescribed transmission zeros are stationary and 2) the reflection zeros are located along an...

In this paper, we present an approach to the synthesis of canonical cross-coupled prototype filters including resonant and non-resonant nodes (NRNs). The family of realizable topologies (including the folded and wheel configurations) is obtained through a recursive extraction technique and is characterized by all the couplings between adjacent node...

In the last 10 or 15 years, exciting new developments have occurred in the field of filters and multiplexers. The two words that best explain this phenomenon are “topology” and “technology.” Thus, this paper will cover new connections, new materials, and new processes. This paper summarizes what is new, describes the new devices, and avoids simply...

We discuss in this work a novel approach to the synthesis of dual-band filters having a parallel-connected topology. The only existing synthesis technique for this class of filters offers a very limited control over the topology of the two constituting filters. The approach we propose allows to control the number of transmission zeros of each filte...

A new class of combiners for base stations of mobile communications is introduced. This combiner allows to share two antennas between two base stations which both use an additional diversity channel in the receiving band. To achieve this result, classical combiners require at least 4 filters and one 3dB divider. With the new solutions only 2 filter...

We describe in this work a procedure for generating a family of canonical prototypes for multiport filtering networks, starting from the transversal canonical prototype. The coupling matrix of the forms generated is be also obtained by applying a suitable algorithm based on Matrix Rotations. Using these tools, a multiplexer synthesized with the sta...

In this paper, we present a novel approach to the synthesis of duplexers with the antenna port matched at all frequencies without the use of 90° hybrids. The design is based on the synthesis of a three-port prototype network composed of coupled resonators, which models the duplexer in a normalized low-pass frequency domain. The polynomials characte...

This article presents a microstrip implementation of a manifold multiplexer. The design procedure is based on evaluation, through an efficient synthesis algorithm recently proposed, of the characteristic polynomials of the triplexer, including the channel filters. Both the manifold and channel filters parameters are also available at the end of the...

In this paper the design and realization of the filtering units included into a Master Head Amplifier (MHA) for base stations (BTS) is discussed. This device allows to improve the overall noise figure of the BTS transceiver by connecting the low noise amplifier at the antenna output, so eliminating the contribute of noise produced by the feeding ca...

This letter illustrates a new procedure for evaluating the characteristic polynomials associated to the prototype of a multiband microwave filter. This procedure is based on the Remez algorithm and allows an equiripple response in the assigned filter passbands and stopbands, once the number of poles in each passband and the number of imaginary tran...

In this letter, we present a method to compute accurately the poles of a lossless N -port device for which the reflection and transmission(s) zeros are known. It does not require any particular symmetry of these roots and only assumes the poles are with a negative real part in the complex frequency domain. The basic concept is based on the cepstrum...

Narrowband microwave filters exhibiting transmission zeros in the response (either imaginary and/or complex) can be typically designed with cross-coupled or extracted pole topologies. These configurations have advantages and disadvantages that must be carefully considered during the choice of a specific topology. In some cases, however, it may be c...

This paper introduces the synthesis of microwave inline filters of narrow or moderate bandwidth which include, in addition to the cavities, “reactive nodes”, which can be implemented either by lumped components or by non-resonating, open or short circuited stubs. The synthesis is approached by means of an equivalent circuit, directly defined in the...

In this article, we present two methods to de‐embed the filters' responses from a diplexer whose junction is known. A weak identification problem is here described by means of a dual‐state junction and can be applied for general diagnosis of prototype diplexers. A strong identification problem based on rationality of the filters is also introduced...

Narrow band microwave filters exhibiting transmission zeros in the response (either imaginary and/or complex) can be typically designed with cross-coupled or extracted pole topologies. These configurations present pro & cons which must be carefully considered during the choice of a specific topology. In some cases it could be however very convenien...

This work faces the problem of combining the outputs of two co-siting BTS, one operating with 2G networks and the other with 3G (or 4G) networks. This requirement is becoming more and more frequent because many operators, for increasing the capacity for data and voice signal transmission, have overlaid the new network in 3G or 4G technology to the...

The design and realization of microwave filters (and selective combiners) has passed through a deep transformation in the last decade. Two reasons have mainly produced this fact: the first is the request of more and more performing devices for the modern communication systems; in particular, the most challenging are the devices used in mobile commu...

Modern microwave communication systems generally employ filtering sub-systems composed of narrow-band filters suitably interconnected, whose purpose is the separation (or combination) of several RF signals allocated in different segments of the frequency spectrum (channels). Such sub-systems are generally referred to as Multiplexers. Actually, seve...

In this work a novel approach to the design of manifold multiplexers is presented, which extend a similar approach previously presented for lumped-junction multiplexers. The filters composing the multiplexer are described through their characteristic polynomials while the manifold network (which may include both lumped and distributed components) i...

In this paper we present a method capable of computing the characteristic polynomials of two filters embedded in a diplexer for which a set of measured external scattering pa- rameters is given. Such a method works under general hypotheses without particular assumptions on the junction or the loss-less nature of the filters. The technique is based...

This paper illustrates a general approach to the synthesis of microwave multiplexers (RF combiners) presenting a star-junction topology (with a resonating junction). The channel filters composing the multiplexer can be arbitrarily specified; in particular, the attenuation characteristic may include transmission zeros (imaginary and/or complex). The...

In this letter, a simple solution is described for obtaining an accurate evaluation of the coupling matrix and the unloaded Q from the measured scattering parameters of a microwave lossy filter (assuming all the resonators with the same unloaded Q). The Cauchy method is applied in a predistorted frequency domain, where the measured (lossy) paramete...

This work presents a design technique for a class of combining networks used in base stations for mobile communications; the considered network is a triplexer composed by three high selectivity filters presenting arbitrary transmission zeros (both complex and pure imaginary), which are connected at the input port through a suitable 4-port junction....

In this paper, we first present a novel synthesis method based on an even- and odd-mode decomposition. This method is capable of synthesizing a network under very general hypotheses and is, therefore, suitable for lossy filter design. To exploit the increased flexibility of this new synthesis method over the traditional lossy design techniques, we...

A recent paper introduced an algorithm concerning the synthesis of lossy filters which allows to exploit some degrees of freedom available in a lossy design. In the original formulation, though, the passivity of the network is not enforced beforehand and requires a check a posteriori. In the present paper we propose an analytical procedure which ca...

In this paper, a novel approach to lossy filter synthesis is presented. First a method is presented to obtain the reflection function once the characteristic polynomials defining the transmission function are specified. This allows to impose arbitrary constraints on the return loss (both in the passband and stopband) leaving unchanged the transmiss...

In this work a technique for designing microwave duplexers using two fully canonical filters is presented (that is filters with the same number of reflection and transmission zeros). The proposed approach is based on the exact synthesis of the prototype network of the overall duplexer; in particular the method presented for evaluating the character...

In this paper the use of generalized coupled coefficients for designing waveguide filters with non-resonating nodes (NRNs) is presented. These coefficients have been introduced in the literature for reducing the difficulties associated to the design of filters using NRNs. The waveguide filters here considered present transmission zeros produced by...

In this letter, we introduce a generalization of the coupling coefficient definition that applies to filters, including nonresonating nodes. The novel coefficients are evaluated from the synthesized low-pass prototype (suitable formulas are given); they allow an easier prototype de-normalization because no complicated network transformation is requ...

It is well known that a Vandermonde matrix generates an ill-conditioned system matrix when applied with finite numerical precision. This deficiency affects the Cauchy method by restricting its application to only lower order systems. This paper presents an innovative and accurate general formulation of the Cauchy method to rectify this limitation a...

In this paper a synthesis technique for dual band filters to be used in base station multi-band combiners is presented. The topology of the dual band filters is constituted by two sub-networks connected in parallel, which are obtained from suitable transformations of the lowpass transversal canonical prototype. The two sub-networks synthesized with...

It is well known that a Vandermonde matrix generates an ill-conditioned system matrix when applied with finite numerical precision. This deficiency affects the Cauchy method by restricting its application to only lower order systems. This paper presents innovative, accurate, and robust formulations of the Cauchy method to rectify this limitation an...

In this article, a process that might be described as "synthesis and approximation" was outlined. Starting from an exact prototype, the desired physical configuration using equivalent circuits and corrections to the resonators due to the influence of the coupling networks was approximated. A process that might be described as "approximation and opt...