This article describes a practical method to design waveguide tapers with smooth profile. A tapered waveguide, in general, is used to match different waveguide sections with the lowest possible reflection level. This method, based on Bernstein approximations, is used to achieve a reflection levels lower than the typical 20 dB in waveguide designs. The taper is designed with a prescribed length for bandwidths beyond the common frequency band of the end waveguide sections. An example of waveguide taper is compared with previous works in terms of reflection and curvature parameters. Finally, a prototype has been simulated and measured with excellent results.

A miniaturized substrate integrated waveguide (SIW) reconfigurable filter is presented in this paper. The filter is based on quasi-lumped substrate integrated coaxial resonators. Varactors are used as tuning elements to enable a continuous control of all filter parameters. To obtain any targeted response, an automated hardware optimization of the filter is demonstrated based on a single-board computer and a high-voltage varactor driver module. This process enables us to obtain the bias voltages of all varactors for obtaining a particular response. Thus, a two-pole filter example, with a compact size of 5.60x5.85 mm(2) has been designed, manufactured and measured, showing different reconfiguration scenarios, both in terms of absolute bandwidth and frequency in the n77 and n78 5G channels.

In this paper, a miniaturized wideband bandpass filter in coaxial substrate integrated waveguide (SIW) technology is presented. To improve the response selectivity and coupling control, a multi-layer structure has been implemented, introducing both strong magnetic and electric couplings. To reduce the physical size of the device, surfaced-mounted device (SMD) capacitors have been integrated on the top layer. These allow both resonant frequency and capacitive coupling level control. Thus, a 4-th order Chebyshev filter with an absolute bandwidth (BW) of 2.9 GHz centered at 5.35 GHz has been designed, fabricated and measured. An extremely small filter size of $7 \times 7$ ,mm2 has been obtained. A study of manufacturing tolerances are also presented in this paper, together with a post-manufacturing response correction allowed by the SMD elements. As it is shown in the paper, the filter’s out-of-band rejection can be easily enhanced by introducing additional transmission zeros (TZs).

A technique for designing bandpass filters with very flat amplitude response is presented in this paper. The approach is based on the use of non-uniform-Q resonators implemented in coaxial substrate integrated waveguide (SIW) technology. An important unloaded Q-factor ratio can be obtained by adequately controlling several layout parameters of the basic resonator cell, thus enabling to optimize the in-band response of the filter. The approach is experimentally demonstrated at X-band frequencies by designing two resonators in Rogers RO4003C (ϵ r = 3.55, tan δ = 0.0027) with unloaded Q-factors going from 53 to 270. Then, a 4th-order filter example with 2 transmission zeros is designed, fabricated and measured based on the former results. The filter is centered at 10 GHz with a 280 MHz bandwidth showing a in-band flatness better than 1 dB-pp, which would require an unloaded Q-factor about 600 for a uniform-Q implementation, therefore showing the advantages of the proposed approach for implementing bandpass filters for high-end RF and microwave applications.

A compact ultra-wideband bandpass filter employing substrate integrated quasi-lumped resonators is presented in this paper. A multi-layer hybrid structure is proposed, combining quasi-lumped resonators and surface mount components. This allows a huge miniaturization degree due to the high capacitive loading. Moreover, strong magnetic and electric couplings can be implemented thus enabling the introduction of transmission zeros for improving response selectivity. A filter example centered at 5.35 GHz with a prescribed channel bandwidth of 2.9 GHz has been designed, manufactured and measured. The filter size is smaller than 7×7 mm2. The obtained results show the feasibility of the proposed approach.

Uno de los requerimientos indispensables en el diseño de las instalaciones donde se trabaja con radiación ionizante es la determinación del espesor adecuado de las paredes, pisos, techo y puertas de los locales, que garanticen dosis por debajo de las restricciones establecidas por la autoridad regulatoria. El objetivo del presente trabajo es desarrollar una herramienta interactiva, libre y de código abierto para calcular los blindajes requeridos en una instalación de Medicina Nuclear. En el código, desarrollado en Phyton utilizando el entorno interactivo Jupiter Notebook, se incluyó el análisis tanto para Tomografía por Emisión de Fotón Único como para Tomografía por Emisión de Positrones. La herramienta fue implementada para el cálculo de los blindajes de un departamento de Medicina Nuclear del Centro Internacional de Restauración Neurológica (CIREN). Esta herramienta libre y de código abierto facilita los cálculos de blindaje aumentando la velocidad, lo que contribuye a lograr una optimización de la protección radiológica, pero también puede usarse como herramienta pedagógica. Palabras clave: Código libre y abierto; cálculo de blindaje; protección radiológica.

Substrate integrated waveguide (SIW) technology [1], [2] is a well established and successful approach for implementing planar microwave filters with very stringent requirements in terms of quality (Q) factor and also with the ability to integrate into a system. Optimized SIW filters can reach a Q factor of 200-800 using low-loss substrates and standard fabrication procedures [3]. Furthermore, packaging and electromagnetic (EM) shielding, power-handling capabilities, and low-cost batch manufacturing are other broadly recognized strengths of this approach. However, SIW filters are still larger than most of their planar counterparts; in addition, advanced topologies are not always easy to accommodate, and filter reconfigurability usually leads to very complex implementation [4]-[6].

The use of singlets, cascaded singlets, and doublets in a coaxial substrate integrated waveguide (SIW) technology is proposed in this paper, with the aim of implementing low-loss filters with very compact size and highly selective symmetric, asymmetric as well as dual-band responses. Singlets based on coaxial SIW resonator structures with source-load coupling are presented and studied. Then, different filter examples based on $N$ cascaded singlets are designed, fabricated, and measured at 7.5 GHz, with up to $N$ transmission zeros that can be easily located below and above the passband. Moreover, the application of doublets based on a dual-mode coaxial SIW resonator with source-load coupling for achieving extremely compact dual-band filters is presented, and two examples with different bandwidth configuration for each channel are designed, demonstrating the flexibility of the proposed coaxial SIW structure. The obtained experimental results of the differently implemented filters show a good agreement with simulations, thus confirming the interesting potential application of these structures for the design of very compact devices with advanced filtering responses.

In this paper, embedded coaxial substrate integrated waveguide (CSIW) filters with innovative magnetic couplings are presented and studied. By creating the loading capacitance of a combline topology using inner layers of a low-temperature co-fired ceramic (LTCC) stack-up, it is possible to achieve resonator miniaturization while improving the spurious-free band and providing full-packaged solutions. Moreover, a new magnetic coupling scheme consisting of short-ended stripline probes is proposed and analyzed in detail, both for direct and external couplings. An in-line three-pole filter at L-band is designed, manufactured, and measured proving how the proposed approach can be used for designing wideband bandpass filter (BPF) with extremely compact size. The designed BPF is centered at 1.5 GHz with 10 % fractional bandwidth (FBW), while the layout size is just 35 × 9.5 mm 2 . The experimental results validate the coaxial SIW technology that allows for, at the same time, easy integration, compact size, flexible design, and enhanced stop-band performance.

Classic formulas for designing direct-coupled band-pass filters are very well-known and widely used. In this paper, such formulas are used in a non-conventional way to overcome some manufacturing limits of coupled-line planar filter implementations. This technique is validated through the design of two prototypes with extremely wide band and high return loss specifications: a classical filter on the resolution limit of standard PCB manufacturing processes and its enhanced counterpart. The measured prototypes demonstrate the feasibility of this method.

This paper proposes an electronically reconfigurable C-band doublet topology based on a dual-mode coaxial substrate integrated waveguide (SIW) resonator with source-load coupling. Varactor diodes in a back-to-back configuration have been used to tune the filter response in terms of center frequency, bandwidth (BW) and return loss (RL) level. The proposed approach presents a high design flexibility in a very compact size, allowing us to prove both tunable BW and constant absolute BW over a tuning range of about 15% at C-band. As a validation example, a single dual-mode coaxial SIW resonator with 10 varactor diodes is used to implement a 2-pole tunable bandpass filter (BPF) with two transmission zeros (TZs) that has been designed, fabricated and tested. The filter has a fractional BW (FBW) range and insertion loss (IL) better than 100% and 5 dB, respectively, over the entire tuning range.

An optimization procedure for the design of miniaturized substrate integrated quasi-lumped filters based on aggressive space mapping techniques is presented in this paper. A gradient-descent approach based on a lossy coarse model is employed. Thus, a 3-pole bandpass filter response centered at 10 GHz is designed, manufactured and measured, showing the validity of the technique even if strong dependencies between the different electrical and physical parameters are present.

The European Higher Education Area (EHEA) defines the competences for professional practice of a Telecommunications Engineer. The School of Telecommunication Engineering of the Universitat Politècnica de València (Valencia, Spain) provides an integrated education program consisting of a Graduate (GITST) + Master (MUIT). The GITST course offers four specialization tracks: Electronics, Telematics, Communication Systems and Multimedia for the proper acquisition of knowledge and competences of the future Telecommunications Engineers. In 2018, the graduate program has implemented a structural change in the organization of subjects for reinforcing important skills, in which a course on digital electronics design and verification (Integration of Digital Systems, ISDIGI) has been transformed into a core subject of the study plan. In this paper, we describe the methodology and adaptation of ISDIGI (i.e. a project-based learning intermediate HDL course that includes design and verification abilities) to the new GITST Curriculum. In addition, this paper describes the process of moving from specialized to core subject.

This paper deals with the design of substrate integrated coaxial filters in multi-layer low temperature co-fired ceramic (LTCC) technology with centre frequency tunability, while keeping constant passband characteristics along the whole tuning range. A structure consisting on switchable embedded capacitances is employed. Moreover, inner and outer layers are used for implementing frequency-dependent coupling structures, enabling to match the required input/output and inter-resonator coupling levels at the different filter states. Thus, a tunable filter with four equidistant centre frequencies in the C-band is designed with nearly constant bandwidth (BW) at the different states. Experimental results show the validity of the proposed approach for implementing frequency tunable coaxial substrate integrated waveguide (SIW) filters with low losses, high selectivity and compact size.

The modeling and design procedure of in-line bandpass filters based on quasi-lumped SIW resonators is presented in this paper. A shunt parallel resonator is implemented by a gap-isolated rectangular patch shorted to ground by means of a via hole. The structure is then embedded into post-wall SIW line, and the proposed resonator can be modeled at circuital level as a quasi-lumped section of a vertically integrated shorted stripline including a capacitive loading at one end. A 3- pole filter centered at 10 GHz with 7% FBW is designed showing very low losses and a huge degree of miniaturization.

The implementation of singlets and doublets in coaxial SIW technology is presented in this paper. The proposed structures are based on the introduction of a direct source/load bypass coupling using end-coupled embedded coplanar lines. The modelling and design of these structures are discussed, and then two prototypes are designed, manufactured and measured, thus showing the validity of the proposed approach and its potential application for implementing highly selective responses in a very compact footprint.

This letter presents a technique for the introduction of transmission zeros (TZs) using half section matched terminations for implementing high selectivity filters in planar technology. The proposed technique does not require any cross coupling between nonadjacent resonators or multiple signal paths, and it can be easily incorporated on any planar filter using lumped, quasi-lumped, and/or distributed elements depending on the desired response. Two different bandpass filter topologies are employed for applying the proposed technique. Both prototypes are designed, manufactured, and measured. The measured results show that the TZs can be independently located very close to the passband edges, without degrading the original filter response.

For the practical implementation of RF and microwave impedance matching networks, a widely employed solution-alternative to the use of classical impedance transformers-is based on tapered lines. This paper shows a simple method to design smooth tapers that take into account the dispersion of the line and the required design bandwidth simultaneously. A planar taper has been designed in microstrip technology with the same length of classical ones but improving their performances. A waveguide prototype has also been designed with similar performance to a commercial one but with one third of its length. Both tapered structures have been obtained through the optimization of very few parameters using the same design strategy. As a result, the reflection coefficient of the tapers can be optimally adapted to a given specific mask using the prescribed value of physical length. Experimental results for both tapers are included for the validation of the proposed topologies and the related design method.