ABSTRACT. This paper presents a new wearable antenna designed for Wireless Local Area Network (WLAN) applications operating at 5.8 GHz using textile materials. To improve the antenna performance and protect the human body from radiation an Artificial Magnetic Conductor (AMC) structure was used. The AMC- integrated antenna was low profile and had much-reduced dimensions. To study the effects of the human body on the performance of the developed antenna, we conducted different simulations with and without AMC using a rectangular multi-layer human body model. The proposed AMC antenna provided interesting simulation and measurement results in free space and on the human body, and the specific absorption rate (SAR) values are also under the IEEE guidelines that guarantee the safety of the wearer.

ABSTRACT. This paper demonstrates the importance of a mesh used for describing a rectangular patch antenna bent over a cylinder and its effect on results and their nature. Advantages of the cylindrical TLM mesh, as the perfectly aligned mesh to the considered structure, are emphasized over the rectangular TLM mesh that requires much finer mesh to be used due to inevitable numerical error introduced by approximations leading to lower efficiency.

ABSTRACT. Flexible interconnects are essential for power and signal transmission in wearable electronics. This paper provides a computational study of the transmission properties of interconnects fabricated on a variety of popular substrates, namely PDS, PI, PET and PU. The contributions to the reflection and transmission losses attributable to each mechanism namely, connector loss, modal loss and conductive loss, are systematically analyzed and quantified. Throughout, the study assumes realistic dielectric and conductive losses.

ABSTRACT. This paper presents a compact size dual-band antenna that can be perfectly integrated into the smartwatch frame. The proposed antenna operates at 2.45 GHz and 5.8 GHz ISM bands and designed on a semi-flexible material of RT/duroid 5880 (εr = 2.2, tanδ = 0.0009) with an overall dimension of 28.5 mm × 19 mm × 1.575 mm. The final design provides a peak gain of 1.8 dB and 3.8 dB and a −10 dB impedance bandwidths of 350 MHz and 570 MHz at 2.4 GHz and 5.8 GHz respectively. The antenna is studied in free space and then on-body scenarios. The SAR analysis in the wrist-worn have also been presented, which are under the normal SAR criteria. These features make the proposed antenna a strong candidate for healthcare applications of smartwatches.

ABSTRACT. Reconfigurability is a key property of modern communication systems, which need to adapt in real-time to changing environments and different operative conditions. Although several approaches to tailor the response of an electromagnetic system have been proposed, the quest for a complete and simple reconfigurable strategy is still far to be solved. Indeed, the possibility to tailor the response of the system typically involves a huge number of control lines and, thus, some critical issues for the practical implementation of the final design. In this framework, we discuss here the possibility of exploiting composite vortex theory for manipulating the response of reflective and radiating systems. In particular, by acting on a limited number of knobs, i.e. the relative amplitude and phase of two superimposed vortex modes, we show that both the radiating properties of patch antennas and the scattering pattern of reflective surfaces can be easily controlled.

ABSTRACT. Next-generation of wireless communications and beyond-5G systems will require extreme performance in terms of low latency, data rates, reliability, just to name a few, and the possibility to tailor the communication channel on demand would be a key enabling technology for the so-called smart environment systems. Therefore, conventional antennas with fixed functionalities cannot be considered an efficient solution, and a new paradigm change in antenna design is thus required. In this frame, here, we show some of the most interesting possibilities enabled by functionalized conformal metasurfaces coating wired antennas for enabling unprecedented electromagnetic behaviours. In particular, we report the design of metasurface coats loaded with electronic elements allowing scattering, frequency, and radiation pattern tunability, in view of the designs of intelligent antennas whose properties can be tailored on demand.

ABSTRACT. In this contribution, we describe a simple and effective approach for the design of phase-gradient metasurfaces based on Huygens cells for oblique incidence. The approach is based on conventional microwave networks and accounts for off-normal incidence onto the cells and for their different response for the two orthogonal polarizations. In addition, it is reported a simple example in which the performance of the angularly-optimized phase-gradient metasurface is compared to the one of an equivalent device designed under normal incidence condition.

ABSTRACT. This work is focused on electromagnetic scattering of PEC objects by collimated Bessel beams, especially for upcoming imaging applications, and on design criteria for innovative Bessel beam launchers at microwaves and millimeter waves. Numerical examples are obtained by exploiting the developed analytical model for scattering, and finally an example of Bessel beam launcher obtained by an equivalent surface impedance on a planar aperture (i.e., building block for metasurface synthesis) is shown.

ABSTRACT. The relationship between the attenuation constant and the quality factor for any kind of propagation media (TEM or not) has been derived. Also, the relationship between the quality factor and the complex resonant frequency has been demonstrated along this communication. Both expressions permit the characterization of any transmission medium. As an example, the correct calculation of the attenuation constant of a ridge gap waveguide has been carried out using commercial software.

ABSTRACT. In this work, numerically efficient surface field optimizations for transverse electric (TE) and magnetic (TM) polarizations are presented to design locally lossless and passive metasurfaces (MTSs) performing anomalous refraction. The MTS consists of the cascade of three patterned metallic layers, modeled through homogenized impedance sheets. A certain number of evanescent Floquet modes are introduced through an optimization procedure aiming at minimizing the real part of the sheets surface impedance. Numerical results show a good agreement between the two cases for a near-perfect anomalous refraction without reflection considering arbitrary incidence and refraction angles.

ABSTRACT. In this contribution, the feasibility of a short range ship collision avoidance system has been investigated. Based on microwave and millimeter wave radars, the system has the aim to accurately detect the presence and distance of possible obstacles inside the harbor. Indeed, whereas ships are usually equipped with long-range radars for the open see navigation, the in-harbor navigation relies only on the manual ability of the captain. An accurate model of the real scenario is proposed by taking into account obstacles of interest like small ships and shore structures. Different operating frequencies have been considered and evaluated, thus proposing a reliable system able to effectively assist the navigation. This contribution paves the way for enabling the concept of autonomous ship navigation by exploiting advanced sensing technologies.

ABSTRACT. In this paper, we present a simple design for the Thru-Reflect-Reflect-Reflect-Reflect (T4R) calibration method, which allows us to develop a closed-form solution for this calibration problem. We compared our T4R method to Thru-Reflect-Line (TRL) calibration. This comparison showed an excellent agreement between T4R and TRL calibration methods.

ABSTRACT. This paper explores the use of the Cardiff nonlinear behavioral model to characterize the response of multiple-input power amplifiers. In particular, a case study is presented on a 300W load modulated balanced amplifier operating at 2.1 GHz. The model mathematical formulation is presented, and the comparison between original data and model shows an error below 3%. More importantly, it is shown that the model can accurately interpolate between characterization points allowing a reduction of up to 96% of the points needed to accurately predict the model behavior. This significantly reduces the simulation and measurement time for multiple-input PA’s whilst attempting to determine the optimal driving conditions.

ABSTRACT. This work presents a circularly polarized side-edge microstrip antenna for (5G) smartphone and Wi-Fi 6 applications. The designed antenna consists of several microstrip lines arranged in a way to produce dual operating bands, in the (5.32 ��� 5.52) GHz band and (6.15 ��� 6.36) GHz band with a percentage bandwidth of 3.69 % and 3.36 % respectively that corresponds to 200 MHz and 210 MHz bandwidth for the two bands. The proposed single element antenna is placed on the top portion of the FR-4 substrate side edge frame and fed by a coaxial SMA connector. The achieved results have exhibited reasonable antenna characteristics in terms of investigated reflection, gain, efficiency, radiation pattern and impedance matching for the two resonating bands.

ABSTRACT. Microstrip antennas are widely used for Wireless Power Transfer applications both in medical and industrial environment, however, a trade-off between performance and dimensions must be set. This article proposes an hexagonal rectenna with enhanced radiation performance. The two-layer structure accounts for an hexagonal ring antenna equipped with concentric parasitic rings, fed by a microstrip line that couples with the antenna parasitic elements in order to achieve optimum matching conditions at 2.45 GHz. The second layer, made by metallized FR-4, allows for enhancing the radiation performance of the overall structure reaching for a 20 % and more than a +1.5 dBi increment in the antenna radiation efficiency and gain respectively, while maintaining overall small dimensions.

ABSTRACT. This research describes a bio-inspired antenna design derived from the shape of a three-petal flower intended for multiple agilities. The proposed design incorporated three PIN diodes corresponding to 8 modes of operation, to achieve pattern diversity and multiple frequency reconfigurable bands. The diodes have been connected between the main hexagonal microstrip radiator and the external parasitic elements, which have a flower petal shape. Pattern reconfigurability has been achieved at 4.675 GHz and 5.2 GHz frequencies, and multi-band frequency reconfigurability was achieved at various center frequencies within the C-band from 4 to 8 GHz range where it can support modern applications such as 5G NR (new radio) and Wi-Fi 6 communications.

ABSTRACT. Terahertz (THz) domain is quickly developing with various applications such as beam diagnostics at particle accelerators, spectroscopy, communications, space science, etc, however, often requiring fast intermediate frequency (IF) electronics. We present the design of a double mirror stub (DMS) based a planar broadband bias tee having an isolation port S31 with 14.45 GHz bandwidth below -10 dB and S33 with 13.1 GHz bandwidth above -2 dB. CST simulation and measured results are in very good agreement. The bias tee will be a part of a new generation of on-chip THz detectors based on zero-bias Schottky diode and high electron mobility field effect transistor (HEMT).

ABSTRACT. Preliminary results on a compact duplexer design for K/Ka-Band for Satcom on the move user terminals are presented. The proposed duplexer is embedded into a package stack-up composed by five dielectric core layers and ten metal layers and it will be integrated with RF chips and antenna element to form an Antenna Front End (AFE). The duplexer functionality is that to split the TX and RX signals, making the antenna using two different paths for transmitting and receiving purpose. The target frequencies are 19.2-21.2 GHz for RX bandwidth and 28-31 GHz for TX bandwidth. The duplexer has been designed using two elliptic bandpass filters, one for TX and one for RX bandwidths. The duplexer is very compact, as its size is only 2.85 mm x 2.8 mm. The simulated Reflection losses are less than 10 dB results, from 19.2 GHz to 20.4 GHz, in RX bandwidth, and from 28.2 GHz to 30.5 GHz in TX bandwidth. The Insertion losses level is approximately 1.5 dB within the bands of interest. The rejection level is approximately -38 dB in RX bandwidth. From these preliminary results, it is possible to state that the proposed duplexer can be very suitable for Satcom systems in K/Ka-band, as its compactness will provide easy feasibility for the integration of the duplexer, with the RF chips and the antenna elements in an Antenna Front End.

ABSTRACT. A wideband aperture coupled rhomboid magneto-electric (ME) dipole for millimeter-wave applications is proposed in this article. The electric dipole is formed by four identical rhomboid patches, while the magnetic dipole is composed by four vertical metallic shorted vias. The use of the rhomboid patches flattens and enlarges the impedance matching bandwidth of the proposed radiating element and powers up the radiating element gain. The proposed configuration is fed using a substrate integrated waveguide (SIW). To proof the proposed idea, a comparison with a simple ME-dipole antenna has been done. The simulated impedance bandwidth with |S11| < -10 dB for the proposed SIW-fed wideband aperture coupled rhomboid ME-dipole is 25% (72-92 GHz). The simulated antenna peak gain is 11.1 dBi at 74 GHz and the 3-dB beamwidth is stable within the band of interest (Eband). The simulations have been performed with Ansys HighFrequency Simulation Software (HFSS). The proposed millimeter wave rhomboid ME dipole antenna can be a valid candidate for applications related to the new 5G technology, especially for 5G backhauling systems scenarios as it targets the E-Band (71-86 GHz).

ABSTRACT. The development of GaN HEMT technology on a Si substrate is one of the main objectives of the semiconductor industry to reduce manufacturing costs as well as to address the monolithic integration of GaN components with Si-based components.

GaN on SiC, which is predominantly used in 4G/5G base transceiver stations, remains one of the most expensive RF semiconductor technologies because of its non-mainstream semiconductor processing. This can limit its potential for large economy of scale. In contrast, GaN-on-Si combines competitive performance with a high-volume capability providing that its production is ported from III-V compound semiconductor foundries to mainstream CMOS manufacturing lines. Over the last few years, ST has put a considerable effort into the development of GaN-on-Si technologies strictly adherent to the workflows of standard CMOS-based process nodes. This enables the manufacturing of a new generation of RF power products for communications, radar, and wireless infrastructure markets, within a consolidated supply chain and without major volume limitations.