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The deployment of wireless devices has increased exponentially in recent years, not only for mobile applications but also for IoT. Typically, these IoT devices exchange data with other devices by means of wireless connections, where battery consumption depends on the antenna system’s efficiency. In applications where long battery life and reliable transmission are essential, improving the efficiency of the antenna is crucial. This study aims to investigate how shaping the ground plane of a wireless device can enhance bandwidth and antenna efficiency, specifically in low-frequency bands of 824–960 MHz, a common frequency band used in IoT where transmitting a small amount of data provides long battery life. Specifically, this work shows that by adding a slot in the ground plane, the current distribution is enlarged, which enables the excitation of its fundamental mode and, consequently, enhances the bandwidth and antenna efficiency by 2 dB. This approach is assessed using three different printed circuit boards (PCBs) that aim to characterise different form factors of IoT devices. A physical prototype is built to validate the results obtained in simulations.

A rectenna structure based on a potentially printable V-shaped nanoantenna (VSNA) design is introduced and numerically analyzed. The characteristics of the VSNA structure have been investigated through the electric field enhancement and radiation efficiency used as figures of merit to evaluate its performance. A comparative study has been performed between the VSNA and a conventional dipole THz antenna based on the same dimension constraints. Therefore, the VSNA has shown better and more localized field enhancement at the arm tips. Furthermore, an optimization process has been carried out to maximize the electric field at the resonance frequency (28.3 THz). The suggested design offers more than 300% improvement in electric field confinement compared to a conventional dipole antenna at 28.3 THz. This enhancement is attributed to the tip-to-tip geometry, leading to a highly localized field at the tip. Further, the optimized VSNA design is employed to form a rectenna structure by inserting an ultra-thin insulator layer between the tips of the antenna arms. The reported rectenna structure increases total efficiency from 11 to 26.58%, with a 141% improvement over previously reported work. Beyond the potentialities presented by the proposed design, its simplicity makes it manufacturable for efficient energy harvesting applications. Finally, the metal–insulator–metal (MIM) diode rectification capabilities have been investigated through a quantum mechanical simulator (built on MATLAB software) with aluminum oxide (Al 2 O 3 ) as an insulator sandwiched between gold (Au) and silver (Ag). The suggested MIM diode (Au/Al 2 O 3 /Ag) offers a zero–bias responsivity of 0.93 A/W, which is higher than the previous work based on Al 2 O 3 which was 0.5 A/W.

The purpose of this publication is to create and correctly analyse a secondary RF line for a hybrid FSO/RF system. Since we want to ensure almost 100% functionality, the design of a secondary RF line is very important. In our case, we have chosen two types of antennas. First, it was a helical antenna that achieves a high level of efficiency and much smaller dimensions compared to horn antennas. The second type was just a horn antenna. Its advantages are high efficiency, high gain, and narrow width of radiation angle. However, large disadvantages are dimensions and the price of these antennas. However, in both cases, we can say that these antennas are suitable for deployment to our hybrid FSO/RF system.

With decades of development, the reverberation chamber (RC) has been proven to be a popular facility to determine antenna efficiency. One-, two- and three- antenna methods have been proposed to measure antenna efficiency without the need of a reference antenna. Due to the stochastic nature of RCbased measurements, the statistical analysis of the uncertainty is indispensable. Recently, the statistical uncertainty models for the one- and three-antenna methods were derived, however, the statistical model for the two-antenna method is still unknown to date. In this paper, the statistical uncertainty model of the twoantenna method is proposed. The approximated relative uncertainty is also given. The derived statistical uncertainty is verified by both simulations and measurements. It is experimentally verified that the statistical model can cope with hybrid stirring and assess the measurement uncertainty with and without frequency stirring in an efficient and convenient way.

In this paper, based on a tangential interpolation function and an adaptively increasing penalty-factor strategy (TIPS), a novel parameterization method with a self-penalization scheme aimed for the topology optimization of metallic antenna design is proposed. The topology description is based on the material distribution approach. The proposed tangential interpolation function aims to associate the material resistance with design variables, in which the material resistance is expressed in the arctangent scale and the arctangent resistance is interpolated with the design variables using the rational approximation of material properties. During the optimization process, a strategy with an adaptively increasing penalty factor is used to eliminate the remaining gray scale elements, as illustrated in examples, in the topology optimization based on the proposed tangential interpolation function. Design results of typical examples express the effectiveness of the proposed TIPS parameterization.

This study investigates the possibility of increasing the radiation efficiency of printed antennas and arrays by suppressing their inherent surface waves using a metasurface made of quad-split rings (QSR). A symmetrical resonant microstrip dipole and a four-element series-fed dipole array printed on an infinite grounded dielectric layer (layer thickness: 0.2 mm; relative permittivity: 9.4; tanδ: 0.0005) were simulated with FEKO 2022 software. Conducted at 100–116 GHz, the numerical results revealed extremely low radiation efficiencies of approximately 31% and 40% for the studied dipole and dipole array, respectively, which resulted from the presence of surface waves in the dielectric. However, placing only one QSR near each dipole arm triggered an increase in radiation efficiency by 2.5 times (up to 75%). The use of a metasurface in the form of two small QSR arrays triggered a pronounced improvement in radiation efficiency, reaching 93.6% and 95.8% for the studied dipole and dipole array, respectively. Analysis of the electric field distribution images showed that this enhancement resulted from surface wave suppression.

Human body tissues have a strong effect on the antenna operation in wireless body area networks (WBANs). In this study, the authors present the deep investigations of the effect of body tissue thicknesses on the performance of an ultra wideband (UWB) loop antenna by simulations when the antenna is operated on contact with tissues. The planar UWB loop antenna is designed for the examinations, which is targeted to be used in UWB WBAN applications. The effect of tissue thicknesses on the antenna performance is analysed and characterised in the terms of reflection coefficient S11, gain and total antenna efficiency, group delay, radiation patterns and specific absorption rate by simulations. A parametric layered human body tissue model with the frequency-dependent behaviour is exploited in the investigations. Further, the reflection coefficient of the presented antenna is measured in the different locations of the author's body. The main aim of these investigations is to demonstrate how the thickness of outermost body tissues affects the antenna performance.

This paper presents high gain and compact Transmit/Receive (TX/RX) integrated antennas in a standard BiCMOS 130nm technology for millimeter-scale millimeter-wave (mm-wave) applications, including high data rate radios and high resolution radars. The proposed TX/RX antenna module utilizes an integrated dipole antenna for the receiver and a slot antenna for the transmitter, placed orthogonally. The achieved gain and radiation efficiency are 5.7dBi and 41.3% for the slot antenna, respectively, and 6dBi and 39% for the dipole antenna. The link budget is improved by 16dB by optimization on the geometry as well as application of a high resistivity hemispheric silicon dielectric lens.

In this study, a compact, triple-band, circularly polarised stacked microstrip antenna is proposed over the artificial eta-surface called reactive impedance surface (RIS) for enhancing antenna radiation efficiency for GPS applications. The proposed design utilises the concept of combining multi-stacked patches with RIS as imaginary-impedance metamaterial-ground-plane for selective frequency reduction of lower bands with improvement in antenna radiation properties for multi-band applications. The circularly polarised (CP) radiation with compact antenna size is achieved for triple-band GPS frequencies of L1 (1.575 GHz), L2 (1.227 GHz) and L5 (1.176 GHz) by placing three stacked patches with two different pairs of symmetric slits, four different sized symmetric cross-shaped slots and truncated corners over RIS. As RIS meta-surface reduces the wave penetration through the lossy substrate beneath it, the proposed stacked patch antenna over RIS demonstrates enhanced forward gain with suppressed back radiation. The measured results for antenna prototype are (1.168–1.185 GHz): L5 band, (1.2–1.245 GHz): L2 band and (1.51–1.59 GHz): L1 band for 10 dB return loss bandwidth with good CP radiation. Forward (boresight) right-handed CP gain of 2.88 dBic (L5 band), 3.25 dBic (L2 band) and 5.53 dBic (L1 band) is observed for compact antenna overall volume of 0.32λo × 0.32λo × 0.024λo at 1.2 GHz.

With the increased use of wireless communication in recent years, the use of reverberation chamber (RC) has increased to a great extent. Reverberation chambers have been eminently used for EMC testing and shielding effectiveness. The environment it provides is very similar to the reverberant surroundings that antenna undergoes in real life use. An experiment to measure total radiated power of antenna, antenna efficiency and quality factor of chamber in indoor environment is proposed. This will make the measurement very simple and inexpensive as designing and calibration of chamber will not be needed. In this paper, we have used three different techniques to compare total radiated power, quality factor, Rician K factor and efficiency of a patch antenna measured in indoor environment with RC data. The three method used include plate stirring method and two time domain methods. The time domain methods use modulated pulse and Gaussian pulse respectively for the measurement. The antenna and chamber parameters are measured in the real time and the data matched well with the RC data for different techniques.