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Starting from the input reflection coefficient of a 1:N divider/corporate-feed antenna, measured when the outputs are short-circuited, a method is proposed to estimate its losses. When the outputs are in phase, as typically occurs in beamforming network applications, the relationship between such an input reflection coefficient and losses is straightforward and variation of reflection with frequency is smooth. When the phases are different from one another, the input reflection coefficient is always smaller than above and oscillates with frequency. The oscillation amplitudes strongly depend on the phase imbalance, and in some cases, reflection can tend to zero. Nonetheless, it will be shown that a preliminary estimation of the losses is still possible. [ABSTRACT FROM AUTHOR]

In this contribution, the authors present guidelines for an effective design of an X-band 2D array of slotted waveguides for surveillance applications. The radiation pattern, with a narrow beam and cosec2 profile, respectively, in azimuth and in elevation, is obtained by a beam forming network based on a hybrid architecture, in which the main corporate feed line feeds identical 11-element travelling wave slotted arrays. The latter produces a radiation pattern that is frequency-independent in azimuth and only slightly frequency-dependent in elevation. The fabricated antenna features a horizontal beam width (at -3 dB) of 1.16°, gain >31 dBi, and 30 dB sidelobe level in the 300 MHz operative band. The overall array is made up of three stacked layers: the first two for the corporate feed line and the third for the travelling wave radiating elements, resulting in remarkably compact external dimensions (170 cm × 25 cm × 2 cm) and relatively low weight (8 kg in total). [ABSTRACT FROM AUTHOR]

When two filters are cascaded together, unwanted spikes appear in the rejection region. These spikes can have a strong impact on the rejection performance of the resulting filter. Therefore, it is desired to suppress or move them far away from the operational band, including part of the rejection band as well. This paper addresses a systematic evaluation of such phenomenon and proposes a simple yet effective method, called spike envelope curve, to have, in a single run and for any frequency, the worst possible case, without the need of repeating onerous analyses. It is also shown that a judicious choice of the length and losses of the line separating the filters can be exploited to mitigate considerably such a negative effect. The method is assessed by full-wave simulations and measurements. [ABSTRACT FROM AUTHOR]

This paper presents an efficient segmentation method of a filter made up of side-coupled cavities that use a reduced complexity model. The model is built by using the reactance matrix of only three parallel waveguides, either coaxial or hollow, coupled via apertures among them. This allows building the databases necessary for fast and reliable analysis and optimization of very complex filters and multiplexers. The method was used to design a low-cost eight-channel coaxial-cavity input multiplexer. [ABSTRACT FROM AUTHOR]

ABSTRACT This article presents a modular reciprocal multiplexer in which the number of channels can be reduced or expanded. The proposed configuration is based on reactive loads designed to substitute channel filters. This is at the same time easy to manufacture and easy to reconfigure as reactive loads are conceived, so as not to modify the characteristics of the active channels if a channel is added or removed. Additional filter tuning after a reconfiguration is not required. The proposed reciprocal design allows for both low costs and low losses since it does not require circulators or additional components, such as hybrid junctions, usually present in reconfigurable multiplexers, although maintaining a good degree of flexibility. A prototype of the proposed design has been fabricated and measured. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:538-546, 2016. [ABSTRACT FROM AUTHOR]

A technique is described to measure the generalized scattering matrix (GSM) of a waveguide device whose ports are multimodal. The device-under-test is placed in between suitable converters, thereby transforming multimodal ports into monomodal ports. The needed data are then measured using a standard vector network analyzer. A dedicated algorithm is finally used to recover the multimode GSM of the device. The experimental validation is reported in this paper for rectangular and square waveguides showing excellent agreement between theory and measured results. [ABSTRACT FROM PUBLISHER]

This paper illustrates the design guidelines and main features of a dual-channel rotary joint, operating in X- and Ka-bands. The core of the proposed solution is the double transducer between X and Ka rectangular waveguides and a nested coaxial waveguide, which shows very good performance in both bands. [ABSTRACT FROM AUTHOR]

Abstract-An (N + 1)-port junction endowed with complete rotational symmetry with respect to the first N ports is analyzed by a partial spectral decomposition of its S-matrix. This approach produces N/2 one-port boundary value problems, as well as a single two-port problem, which can be easily solved by means of standard full-wave simulators. The practical example of a coaxially fed 36-way power divider was easily analyzed by this method, and the results were nearly indistinguishable from those obtained by analyzing the device as a whole. [ABSTRACT FROM AUTHOR]

This paper introduces a general method for the analysis of the individual blocks forming a complex circuit by measurements or simulations carried out on the whole. This is useful in those situations where the analysis of the single blocks is difficult. Paradoxically, the analysis of more complex structures, which contain individual elements, as subcircuits is, in some circumstances, easier to perform or may even be the only way to acquire information about the individual elements. Under certain conditions, the elements can be combined to obtain different circuits according to classic segmentation technique. Owing to its formulation, the method is applicable to both simulation and measurement problems. [ABSTRACT FROM AUTHOR]

The filter prototype of side-coupled coaxial filters, which we recently proposed, has been modified to suit an ar- rangement in which the coupling apertures are placed on the side opposite the coaxial end gaps. In this situation, the modified prototype fits the physical counterpart better, resulting in a fur- ther design simplification. In addition, the feeds have also been modeled and included into the prototype, thus enhancing the correspondence between the prototype and physical structure. A practical design, concerning a WIMAX application, shows the reliability of this solution. [ABSTRACT FROM AUTHOR]

This paper presents a method for the design of compact diplexers, where the common junction is considered part of the filters, thus reducing the diplexer length by roughly one cavity. Starting from two filter prototypes satisfying the desired specifications, the technique provides the design equations in closed form. Effectiveness and accuracy of the proposed method are demonstrated by means of a practical example. [ABSTRACT FROM AUTHOR]

A strategy for the full-wave analysis of slotted waveguide planar arrays is presented and demonstrated. The core of the method is a suitable segmentation of the antenna into two fundamental regions: an ‘internal’ one, formed by the waveguide circuit, and the ‘external’ one, consisting of the half space above the plate where the radiating slots are located. The internal region is further segmented into several blocks, connected to each other via their generalized admittance matrices (GAMs). The latter are calculated by means of either a commercial or a home made tool. The front plate is considered as a whole and analyzed by the moment method, in terms of modes of the slots. The latter are considered as short sections of waveguide whose length is just the conductor thickness, connecting the internal and external regions. The approach has been applied with success to a number of large planar arrays, both in rectangular and ridge waveguide. [ABSTRACT FROM AUTHOR]

This paper presents a novel kind of circuit prototype suitable for modeling of coaxial cavity filters, where all cavities are coupled sidewise. Initially, the parameters of the prototype are explicitly derived from those of the classical Cohn's inline filter, which is assumed as the starting point. The main feature of the proposed adaptive model is its one-to-one correspondence to the physical structure, making design feasible without additional optimizations or expensive tuning. Another feature lies in that the prototype is adapted to the structure along the way in the synthesis process. A practical example shows the merits and the accuracy of the proposed prototype. The relationships between the proposed method and existing techniques are also discussed. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of deriving an actual coupled-line model from the "spot frequency" characteristics of transmission media derived by means of a numerical electromagnetic simulator. For a given set of coupled lines, possibly asymmetric and lossy, one of the main issues is to recover a model whose parameters are physically and practically meaningful. In order to satisfy the requirements, the model ought to basically yield a natural generalization of the well-known even/odd and c/π modes for couples of lines, and collapse to a set of uncoupled lines when coupling is negligible. Hence, part of this study is devoted to discussing and evaluating models that satisfy such requirements. The end result is a Weissfloch-type equivalent circuit made up of uncoupled lines and input and output ideal transformers. The algorithm is then applied to the network parameters of coupled lines. The latter are evaluated by a full-wave method of moments approach, and a subsequent short-open calibration (SOC) procedure. Finally, a new algorithm is introduced that is able to evaluate and remove the contribution of the naked discontinuity due to ports, usually not directly available from the SOC routine. [ABSTRACT FROM AUTHOR]

Considers the Helmholtz equation in the elliptic-cylinder coordinate system for solving the capacitive and inductive irises in rectangular waveguides. Application of the method to a capacitive window; Description of inductive window; Frequency extraction of the study; Results of the application of the approach; Conclusions.

Relevant properties and appropriate methodology should be defined to support engineers during the material selection process. Environmental requirements are generally included in projects and processes that are already defined instead of inserting environmental requirements in conceptual early design stage. Life Cycle Assessment (LCA) is the most recognized methodology for the evaluation of environmental burdens, which is related to a product or a service during all the life cycle stages, from the extraction of raw materials to the end of life. Nevertheless, a rigorous quantitative assessment of all burdens is a time-consuming task and requires deep skills of those involved, leading many companies to abandon this approach. In this study, the embodied energy and carbon footprint will be used for assessing the environmental burden, not for replacing a complete LCA, but for providing fast and reliable information to those involved in the design of a new product. The present work applies data published in the literature to the validation of the proposed materials selection procedure. The results showed that it is possible to use a reliable software with metrics of embodied energy and carbon footprint to pre-assess the environmental burden in the early stages of development and materials selection. Unlabelled Image • Materials with lower environmental impact can be selected in the first stages of product development. • Embodied energy and carbon footprint are indicators for selecting materials with lower environmental burden at the product life cycle. • A materials selection software is a tool to incorporate environmental issues in decision-making strategies for product design. [ABSTRACT FROM AUTHOR]

A correction to the article "A Technique for the Measurement of the Generalized Scattering Matrix of Overmoded Waveguide Devices" published in the October 2013 issue of the journal is presented.

Scanning microwave microscopy (SMM) is a novel metrological tool that advances the quantitative, nanometric, high-frequency, electrical characterization of a broad range of materials of technological importance. In this work, we report an inverted near-field scanning microwave microscopy (iSMM) investigation of a graphene oxide-based epoxy nanocomposite material at a nanoscopic level. The high-resolution spatial mapping of local conductance provides a quantitative analysis of the sample's electrical properties. In particular, the electrical conductivity in the order of ∼ 10 − 1 S/m as well as the mapping of the dielectric constant with a value of ∼4.7 ± 0.2 are reported and validated by the full-wave electromagnetic modeling of the tip–sample interaction. [ABSTRACT FROM AUTHOR]

ABSTRACT A substrate integrated waveguide Magic Tee with very compact size and operating over a wide band is proposed. The circuit is made of two stacked substrates connected by cutting a small aperture between them. This solution presents slightly higher complexity compared to a single substrate magic Tee but it avoids the radiation losses because the circuit is completely closed. A simple and effective procedure is used to design the circuit. A prototype is built and experimental results show a good agreement with simulations. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:932-936, 2016 [ABSTRACT FROM AUTHOR]

ABSTRACT A substrate integrated waveguide six-port directional coupler is designed and characterized. The circuit exploits a very compact size and good reflection and transmission characteristics, as it exhibits both return loss and isolation higher than 15 dB over a 13% bandwidth. The device is made by connecting all ports to a single junction which mixes all signals. Some prototypes have been built and experimental results show a very good agreement with simulations. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2589-2592, 2015 [ABSTRACT FROM AUTHOR]

ABSTRACT This article presents a methodology that allows the determination of the matrix representation of a package. The methodology is based on a set of calibration measurements, picked up at the external pins of the package, of a set of known integrated circuits. The representation of the package can be used both for a correct measurement of the embedded devices and to improve the design of integrated circuits. The effectiveness of the technique is demonstrated by the de-embedding of a packaged passive integrated inductor and the design of a low noise amplifier. The measurement sets were obtained through computer simulations. The effects of added noise on data, like measurement errors, are also investigated, and an approximate methodology, able to reduce these effects, is suggested. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:623-634, 2014. [ABSTRACT FROM AUTHOR]

The design and characterization of a single-layer wideband substrate integrated waveguide 3-dB standalone directional coupler are described. The device exhibits a bandwidth of 2 GHz, ranging from 10.7 to 12.7 GHz, and both return loss and isolation better than 15 dB. The coupler has been built using a TACONIC RF-35 A2 substrate. A very good agreement between simulations and experimental results is obtained. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1141-1144, 2014 [ABSTRACT FROM AUTHOR]

Near-field scanning microwave microscopy is a technique with increasing popularity for the study of nanometer-scale electrical properties of samples. Here, we present an approach to quantify sample properties in images obtained with an inverted scanning microwave microscope (iSMM), recently introduced by our group. In particular, this study reports the analysis of the local electrical conductivity of a platinum diselenide sample and proves its semimetal behavior. The approach is validated by a full-wave numerical model, reproducing the complete iSMM operation as well as all steps of the calibration algorithms. To extract local sample properties, this article provides two calibration procedures, respectively, for transmission and reflection mode measurements, based on a two-port equivalent circuit of the iSMM. This enables the high-frequency quantitative characterization of a wide variety of samples and surfaces. [ABSTRACT FROM AUTHOR]

Near-field scanning microwave microscopy (SMM) employs microwave radiation to image and characterize samples down to the atomic scale, including soft biological structures or inorganic materials, such as ferroelectric films. However, SMM generally also senses sample topography; hypersensitivity to topography becomes problematic with additional parasitic contributions and may partially or completely mask nontopographic sample features in the data, such as contrast in electrical conductivity or permittivity. This work proposes a simple and effective procedure to remove unwanted parasitic effects from SMM images. Differently from existing procedures, the method is applicable either in postprocessing or in real time, i.e., during the scanning operation. This allows the immediate visualization of nontopographic sample features in the instrument screen. As a proof of concept, hafnium zirconium oxide (HfZrO) ferroelectric film with high surface roughness is studied; unwanted contributions were removed from SMM data, providing a clear map of the sample ferroelectric structure that was originally hidden. [ABSTRACT FROM AUTHOR]

This paper presents an instrument called an inverted scanning microwave microscope (iSMM), which is capable of performing noninvasive and label-free imaging and characterization of intracellular structures of a live cell on the nanometer scale. In particular, the iSMM is sensitive to not only surface structures but also electromagnetic properties up to one micrometer below the surface. Conveniently, the iSMM can be constructed through straightforward conversion of any scanning probe microscope, such as an atomic force microscope and a scanning tunneling microscope, with a simple metal probe to outperform a traditional SMM in terms of ruggedness, bandwidth, sensitivity, and dynamic range. By contrast, the application of the traditional SMM to date has been limited to mainly surface physics and semiconductor technology because the traditional SMM requires a fragile and expensive probe and is incompatible with saline solution or live cells. [ABSTRACT FROM AUTHOR]

A process for the fabrication of dielectricless rectangular waveguides (RWGs) integrated in the substrate is presented and experimentally validated. First, two complementary circuits are realized through milling the guide in a substrate and, then, are metallized with traditional additive processes used in printed-circuit board industry. Next, the circuits are joined together, and electric continuity is enforced through two additional rows of conductive holes along the guide sidewall, as it occurs in the substrate-integrated waveguide technology. A comparison between the propagative characteristics of a classic RWG and a waveguide with this methodology is reported. Finally, a slotted waveguide realized by this technology is fabricated and measured. [ABSTRACT FROM PUBLISHER]

In this work, we introduce a hybrid atomic-force/near-field scanning microwave microscope, exploiting the tomographic capabilities of the microwave microscopy to explore structures of relevant interest, namely, samples involving both biological and non-biological materials at the same time. In particular, we show imaging of C2C12 muscle cells grown in the presence of bundles of multi-walled carbon nanotubes: here, the microwave microscopy, by virtue of its tomographic potentiality, highlights how cells incorporate some nanotubes in their fibers. [ABSTRACT FROM AUTHOR]

In this paper, we describe how to define and build a set of known loads to be used in near-field microwave microscopy. Such loads are necessary to set up a microwave calibration kit, enabling local quantitative measurements by the microscope. The proposed protocol is validated through the microscopy system we have recently developed that combines a scanning tunneling microscope and a 70-GHz vector network analyzer. [ABSTRACT FROM AUTHOR]