Circumference-length dependency of the wireless power transmission (WPT) performance between the circuit-shape leaky waveguide and a $\lambda/2$ wavelength dipole antenna was analyzed by utilizing the FDTD method. The proposed waveguide was composed of a pair of straight waveguides with slot openings and a pair of semicircular waveguides to effectively melt snow with microwave radiation [1] with reducing heavy snow removal workloads [2]. The WPT efficiencies between the waveguide and the $\lambda/2$ dipole antenna located 30-mm above the waveguide with parameterized circumference length were calculated from the S-parameters [3] by the FDTD method.
Increasing demands on high-performance platforms in the sixth generation (6G) of mobile communications raise research focus on new transducers that can address both the coverage and power issues. One of the key technologies recently adopted to design and implement such promising features is metasurface (MTS). MTSs are two-dimensional low profile artificial materials realized by electrically small meta cells. Providing particular impedance boundary conditions (BC), they have a variety of applications that extensively increased their usage during the last decade. The need for reconfigurability and having a dynamic electromagnetic response resulted in introducing the reconfigurable intelligent surfaces (RISs) as one of the new popular MTSs in recent years [1].
Device-Free Localization (DFL) employs passive radio techniques capable to detect and locate people without imposing them to wear any electronic device. By exploiting the Integrated Sensing and Communication paradigm, DFL networks employ Radio Frequency (RF) nodes to measure the excess attenuation introduced by the subjects (i.e., human bodies) moving inside the monitored area, and to estimate their positions and movements. Physical, statistical, and ElectroMagnetic (EM) models have been proposed in the literature to estimate the body positions according to the RF signals collected by the nodes. These body models usually employ a single-antenna processing for localization purposes. However, the availability of low-cost multi-antenna devices such as those used for WLAN (Wireless Local Area Network) applications and the timely development of array-based body models, allow us to employ array-based processing techniques in DFL networks. By exploiting a suitable array-capable EM body model, this paper proposes an array-based framework to improve people sensing and localization. In particular, some simulations are proposed and discussed to compare the model results in both single- and multi-antenna scenarios. The proposed framework paves the way for a wider use of multi-antenna devices (e.g., those employed in current IEEE 802.11ac/ax/be and forthcoming IEEE 802.11be networks) and novel beamforming algorithms for DFL scenarios.
Nowadays, Human Body Shadowing (HBS) prediction is of prevalent interest for wireless communications, especially for millimeter waves (mmWaves), Wireless Body Area Networks (WBANs), and pedestrian crowds in dense urban environments. In this paper, HBS is predicted using a propagation model based on an elliptic cylinder (with or without a sphere for the head) for the human body geometrical model and Uniform Theory of Diffraction (UTD) for the associated electromagnetic theory. Indeed, this kind of model can be useful to study body orientation influence on human blockage phenomenon. Moreover, to analyze the contribution of such a model, we also compare it with UTD single circular cylinder models and with 2.4 GHz radio measurements coupled to Motion Capture (MoCap).
We propose a wideband small cancellation circuit enabling control of amplitude-frequency characteristics by using two variable resistors. First, the formulation of the proposed circuit is described. Next, we show that by appropriately designing the variable resistor parameters, it is possible to form amplitude-frequency characteristics of concave, convex, and flat shapes. We also show that absolute amplitude values can be controlled at a design frequency.
Numerous techniques to realize a discone antenna and its enhancements either to improve its performance characteristics or manufacturing process have been reported by academicians and researchers [1]–[3]. A discone antenna, which mainly consists of two parts, i.e., the disc and the cone, was developed by modifying the conventional one using six flared hexagonal panels to reduce the complexity of cone realization [1]. By advantaging a 3D printing technology, a discone antenna based on polylactid acid (PLA) filament has been realized with the reduction in cost of fabrication [2]. While in [3], a skeletal discone antenna whereby the cone part is developed by integrating 3 circular-rings and 8 straight thin copper wires has been characterized experimentally to produce a wideband frequency response.
This presentation will focus on recent developments in the finite difference time domain (FDTD) method for the solution of several electromagnetic and antenna problems. First a brief introduction of the method, its unified formulation, its capabilities, and the integration of linear and non-linear circuit elements in the electromagnetic simulation. Several examples of designing antennas, filters, and RFID tags as well as RCS computations of large targets will be demonstrated. This will be followed by the demonstration of how to examine the numerical results to accurately achieve successful simulations and how to eliminate numerical or geometry assignment errors. The speed up of the FDTD method using graphical processing gaming cards (GPUs) along with the use of different programming languages such as FORTRAN, MATLAB, CUDA, and OpenCL will be highlighted.
Cell broadcast (CB) is an essential tool in the Global System for Mobile Communications (GSM) mobile system that allows the broadcast of messages to mobile users, which are located within a cell coverage. The CB tool is used to provide alert and warning messages, for instance: public safety messages, weather warnings and any type of emergency alerts (e.g., tornadoes, hurricanes, floods, child abductions, hazardous situations). Nevertheless, considering rural areas, where the local population is scattered and there is poor mobile coverage, it is challenging to guarantee that mobile users receive the alert CB messages. Furthermore, telecommunication operators may not prioritize investing in complex and modern infrastructure in such remote locations. In this context, the utilization of Software Defined Radio (SDR) technology can help to improve the coverage and reliability of cell broadcast in such locations. Therefore, the contribution of this scientific paper is the deployment of a low-cost and low-power implementation of a Cell Broadcast network using an SDR device and an open-source project to allow the broadcast of messages to mobile users in rural areas.
This work presents a new method for the bandwidth enhancement of the dielectric resonator antenna (DRA) at the millimeter-wave (mmW) band. This work enlarges the coupling aperture under the dielectric radiator to achieve bandwidth enhancement. Conventional aperture-coupled DRAs use a small aperture for excitation, which only consists of the fundamental mode and thus limits the operating bandwidth. The proposed large aperture coupling can excite both fundamental and higher-order modes together inside the DRA, which extends the impedance bandwidth from 6% to 30%. Comparison between using a small aperture and a large aperture for exciting the DRA shows that the large aperture can lower the input impedance of the DRA, and help achieve the wide impedance bandwidth. A 2 × 4 array with the proposed antenna element was simulated. The simulated results show that the proposed DRA array can achieve an impedance bandwidth of 30% from 25 to 34 GHz (for reflection coefficient ≤ -10 dB). Throughout the entire operating bandwidth, stable broadside radiation patterns with low cross-polarization levels under -40 dB can be observed.
A Magneto-Inductive Wave (MIW) structure for wireless power transfer (WPT) is proposed with switchable mutual inductance between neighbored coupling coils. Orthogonally placed switchable short circuit loops are added in order to modulate the wave propagation properties of the MIW structure without changing the resonance frequency. We derive an analytical model based on lumped circuit analysis for the MIW waveguide and successfully evaluate the theoretical findings by circuit modeling and field simulation. We demonstrate switchable, i.e. addressable, guided wireless power transfer along an experimental MIW structure at a resonance frequency of 20.5 MHz.
This paper presents, an improved applied approach using genetic algorithm optimization for super-ultra wide band antenna. The intended antenna is optimized to operate from 2.8 GHz to more than 40 GHz and suggested for UWB wireless communications include 5G applications. Improving the impedance bandwidth is achieved by optimizing appropriate non-conventional defected ground structure (DGS) filter. The optimized non-conventional filter consists of a matrix of rectangular shapes where each one is allocated by either conducting or non-conducting property. The process is based in a code developed using visual basic script of CST microwave studio. Additionally, the optimized form can be automatically achieved without designer intervention. The simulated results for reflexion coefficient, current distribution, radiation pattern and gain are presented and discussed.
In this paper, we present a set of efficient dimensionality reduction methods for array signal processing using $\ell_{1}-$ Kernel-based multiplication-free PCA ( $\ell_{1}$ -MF-PCA) techniques. Our proposed $\ell_{1}$ -MF-PCA methods utilize $\ell_{1}$ -norm kernels, which enhance the robustness of the approach compared to classical $\ell_{2}$ -PCA. Additionally, we demonstrate that the $\ell_{1}-$ MF-PCA methods are energy-efficient, reducing the number of multiplication operations significantly. Multiplication operations are known to be costly in terms of energy consumption in many processors. Furthermore, we extend the $\ell_{1}$ -MF - PCA methods into the complex-valued versions for the direction of arrival (DOA) estimation task. We experimentally show that the proposed methods are robust to outliers and outperform traditional approaches in terms of accuracy and efficiency. Our results demonstrate the potential of the proposed $\ell_{1}$ -MF - PCA methods for array signal processing applications, particularly in energy-constrained settings.
This paper presents the manufacture and measurements of a circularly polarized cavity-backed patch antenna for active electronically Ka-band array with a beam scanning capability over a wide-angle range $(+/-60^{\circ})$ . The proposed unit-cell is manufactured in two versions for both 18–20 GHz (Rx) and 28–30 GHz (Tx) bands. It comprises an upper patch coupled to a dual pin-fed lower patch, both separated by a metal grid spacer. The proof of concept is given through simulation and experimental measurements on Rx and Tx mockups.
A novel wide dual-band, Multiple-Input Multiple-Output (MIMO) antenna design for the upcoming fifth generation (5G) wireless communication is presented in this work. The size of single element of the proposed MIMO configuration is 4×5 mm 2 having L-shaped slot at the top edge. Rogers TMM4 with thickness of 0.508 mm having relative permittivity of 4.5 is used as a substrate material. Resonating frequencies of single antenna element are 40.15, 67.80 and 91.23 GHz with a wide impedance bandwidth of 2.22 and 34.43 GHz, respectively. The return loss at resonating frequencies are − 29.25, −66.30. and −20.00 dB with a good gain of 5.51, 4.27 and 3.70 dBi, respectively. The overall size of proposed 1×2 MIMO antenna is 4×7 mm 2 with a separation of 3.6 mm in between two elements and 0.6 mm separation between the edges and elements. The resonating frequencies of the proposed MIMO antenna are 40.36 GHz with reasonable gain of 4.62 dBi, and 67.59 and 95.73 GHz with improved gain of 5.42 and 5.70 dBi, respectively. The simulated return loss below −10db at resonating frequencies are −21.92, −63.38 and −27.87 dB, respectively. Inter-port isolation of above 20 dB throughout the operating frequencies, is achieved without using any complex technique. Envelope Correlation Coefficient (ECC) and Diversity Gain (DG), are important MIMO antenna parameters are less than 0.001 and 10 dB respectively. The proposed design with a high radiation efficiency at resonating frequencies is a good candidate for the satellite and radar communication as the achieved operating range lies in the proposed Ka-band (26–40 GHz), V-band (40–75 GHz), E-band (60–90 GHz) and W-band (75–110 GHz).
This paper proposes a low-profile dual-polarized antenna for base station applications with wideband transmission characteristics. The radiator of the antenna consists of a square patch etched with a cross slot of gradient width, which provides both radiation and transmission characteristics. The proposed radiator enables stable radiation patterns, high isolation, good transmission characteristics, and a low profile $(0.14\lambda_{0})$ . Simulation results show that the impedance bandwidths (VSWR< 2) of the two polarizations are 25.5% (1.88 to 2.43 GHz) and 20.6% (1.91-2.35 GHz), respectively. Moreover, the isolation between the two ports is greater than 25 dB within the operating band. The antenna achieves high gain over 9 dBi and stable radiation patterns with a 3 dB beamwidth of 62°. Additionally, the transmission characteristic at the high-frequency band (3.65GHz) is ensured.
The criteria for choosing the number and shape of the subarrays are examined. We propose a possible sub-array configuration that seems capable of offering good performance in terms of jammer and clutter cancellation.
Artificial material has been realized by arranging metal particles in some periodic structures. The main difference from a natural material is that the effective permittivity of the artificial material can be controlled by adjusting the size of metal particle, the density of metal particles and the arrangement method. This leads to a possibility of freely realizing a required value of dielectric constant. In our former study, an artificial material has been designed, and was used to enhance the gain of the microstrip patch antenna following the principle of RCA (Resonant Cavity Antenna) with one layer of dielectric slab [1] [2]. In this study, RCAs that utilizes two layers of artificial materials are presented.
We have developed a small, mobile and autonomous instrument to measure electric field and electric conductivity of air in different conditions found in the Earth atmosphere. The size of our instrument is determined by the size of the industrial PC-104 board. Other “home-developed” cards (electronic boards of the electric field measuring, power board) have the same format as the PC-104 one. All are stacked in a metallic box together with the Li-ion batteries that insure up to 10 hours of autonomy. Collected data are saved in an internal memory. The electrodes and their booms are accommodated on the box. The box size is 12 × 12 × 20 cm and its weight is 2 kg. Thus, easy to put your backpack to walk till the measurements site.
