Search Results (606)

This article presents the design of a novel, compact, 4 × 2 planar-array antenna that provides quad-beam radiation in the broadside direction, and it enhances coverage and serviceability for millimeter-wave applications. The antenna utilizes a corporate (parallel) feed network to deliver equal power and phase to all elements. Non-uniform element spacing in the two orthogonal planes, exceeding 0.5${\lambda }_1$ (${\lambda }_1$ being the wavelength at 30 GHz), results in a quad-beam radiation pattern. Two beams are formed in the xz-plane and two in the yz-plane, oriented at angles of $\theta =\pm 54°$. However, this spacing leads to null radiation at the center and splits the radiation energy, reducing the overall gain. The measured half-power beamwidth (HPBW) is 30° in the xz-plane and 35° in the yz-plane, with X-polarization levels of −20.5 dB and −26 dB, respectively. The antenna achieves a bandwidth of 28.5–31.1 GHz and a peak gain of 10.6 dBi. Furthermore, increasing the aperture size enhances the gain and narrows the beamwidth by replicating the structure and tuning the feed network. These features make the proposed antenna suitable for 5G wireless communication systems. Full article

Using the method of moments, we analyze three array antennas for low cross-polarized radiation. Each antenna comprises two dual-loop elements connected to a feedline horizontal to the ground plane. First, a feedline end is excited with an unbalanced source as a reference antenna. Next, the feedline center is excited with a balanced source, after the transformation of a decoupling array configuration. It is found that the antenna exhibits a cross-polarized radiation lower by 12 dB than the reference antenna. Last, the decoupling antenna is modified to have an unbalanced source without a complicated balun circuit design. It is pointed out that the modified antenna is an array of four loop elements, sequentially rotated by 90º. Full article

Energy harvesting technology allows Internet of Things (IoT) devices to be powered continuously without needing battery charging or replacement. In addressing existing and emerging massive IoT energy supply challenges, this paper presents the design of multi-sourced multiple input and multiple output (MIMO) multiband hybrid wireless RF-perovskite photovoltaic energy harvesting subsystems for IoT application. The research findings evaluate the efficiency and power output of different RF configurations (1 to 16 antennas) within MIMO RF subsystems. A Delon quadruple rectifier in the RF energy harvesting system demonstrates a system-level power conversion efficiency of 51%. The research also explores the I-V and P-V characteristics of the adopted perovskite tandem cell. This results in an impressive array capable of producing 6.4 V and generating a maximum power of 650 mW. For the first time, the combined mathematical modelling of the system architecture is presented. The achieved efficiency of the combined system is 90% (for 8 MIMO) and 98% (for 16 MIMO) at 0 dBm input RF power. This novel study holds great promise for next-generation 5G/6G smart IoT passive electronics. Additionally, it establishes the hybrid RF-perovskite energy harvester as a promising, compact, and eco-friendly solution for efficiently powering IoT devices in smart cities. This work contributes to the development of sustainable, scalable, and smart energy solutions for IoT integration into smart city infrastructures. Full article

Light detection and ranging (Lidar) is a key enabling technology for autonomous vehicles and drones. Its emerging implementations are based on photonic integrated circuits (PICs) and optical phased arrays (OPAs). In this work, we introduce a novel approach to the design of OPA Lidar antennas based on Si₃N₄ grating couplers. The well-established TriPleX platform and the asymmetric double stripe waveguide geometry with full etching are employed, ensuring low complexity and simple fabrication combined with the low-loss advantages of the platform. The design study aims to optimize the performance of the grating coupler-based radiators as well as the OPA, thus enhancing the overall capabilities of Si₃N₄-based Lidar. Uniform and non-uniform grating structures are considered, achieving θ and φ angle divergences of 0.9° and 32° and 0.54° and 25.41°, respectively. Also, wavelength sensitivity of 7°/100 nm is achieved. Lastly, the fundamental OPA parameters are investigated, and 35 dBi of peak directivity is achieved for an eight-element OPA. Full article

The design of a multilayer SIW cavity-fed filtenna is presented. The proposed filtenna can be used as a unified module in an antenna array structure. It consists of three-pole bandpass filter with slot antenna positioned centrally within the top module surface. The modules aperture dimensions of ${\lambda }_0/2\times {\lambda }_0/2$ in conjunction with an SMA feeding port located on the bottom filtenna surface allow implementation of an antenna array of different configurations. This approach allows greatly simplifying the feeding and matching scheme of the array. This module is designed to operate at a 2.655 GHz central frequency with a 70 MHz bandwidth. The procedure of the filtenna design is described in detail. The proposed filtenna was fabricated and tested. The simulation and measurement results show a good agreement. The measurements demonstrate that the maximum measured gain of the prototype is 3.64 dBi with a small variation in the passband. Full article

We have proposed a multi-strategy enhanced particle swarm optimization (PSO) algorithm to optimize the antenna spacing distribution of an optical phased array (OPA). The global search capability is improved by incorporating circle chaotic mapping initialization and an updated strategy based on adaptive inertia weights and dynamic learning factors. We used the peak side-lobe level (PSLL) at different steering angles as the fitness function, which effectively suppresses the rapid degradation of PSLL during scanning. Based on this approach, 32- and 64-channel aperiodic OPAs were designed with a scanning range of ±60°, with improvements of the PSLL of 1.94 and 2.05 dB at 60°, respectively. In addition, the analytical and numerical simulation results are in good agreement. We also analyzed the influence of spacing deviations on PSLL and found that the obtained OPAs exhibit sufficient robustness. Full article

Beam-switching technology is critical for fifth-generation (5G) Frequency Range 1 (FR1) base stations, yet existing odd-number Butler matrix designs often struggle to achieve compact size, low complexity, and efficient performance. Although a few studies have investigated 5 × 5 Butler matrices, their reliance on waveguide structures or multilayer implementations leads to larger footprints and greater fabrication complexity. This work introduces a novel 5 × 5 Butler matrix integrated with a five-element dipole antenna array for 3.3–3.7 GHz applications, offering notable improvements in beam-switching efficiency and overall system design. The proposed matrix generates five distinct beams at −144°, −72°, 0°, 72°, and 144° by employing precise phase progression, while eliminating crossovers and power dividers to simplify the layout. With a compact footprint of 2.67 × 0.80 × 0.02 cubic wavelength—94.4% smaller than waveguide-based designs—the matrix achieves a bandwidth of 3.32–3.62 GHz and consistently covers the target beams. The integrated system attains measured gains up to 11.4 dBi and half-power beamwidths ranging from 7.96° to 23.66°, with sidelobe levels comparable to those of state-of-the-art configurations. By employing a low-loss substrate, the gain can be further enhanced by as much as 6.81 dB, highlighting the potential for additional performance gains. These innovations establish the proposed design as a compact, low-complexity, and high-performance solution for 5G base station applications. Full article

An electromagnetic (EM) absorber-embedded Ka-band double-layer tapered slot antenna (DLTSA) is proposed in this work. The EM absorber is placed on both sides of the tapered radiating slots as a means of achieving the reduced monostatic radar cross section (RCS) at the X-band. A conventional tapered slot antenna (TSA) with EM absorbers at the same position suffers from the distorted current distribution from the feedline to the radiating slots and causes a degraded radiation performance with a tilted beam. In contrast, the DLTSA with EM absorbers maintains the impedance and radiation characteristics of the antenna without the EM absorbers, while achieving the reduced monostatic RCS for the cross-polarized incident wave. The functionality of the reduced RCS is verified with the 4-by-4 DLTSA array design. The 4-by-4 array prototype with FGM-125 EM absorbers is matched at the Ka-band with a 14.7 dBi boresight gain at 35 GHz. The monostatic RCS is measured in an indoor environment, showing 6.5 dB monostatic RCS reduction at the X-band on average, verifying the computed expectations. This work validates the possible use of EM absorbers at the front side of a missile seeker composed of end-fire radiating elements. Full article

This work introduces a high-performance multi-input multi-output (MIMO) antenna design to operate at the 28 GHz band. The proposed four-port MIMO antenna, in which each port comprises a 1 × 8 series-fed array, achieves peak gains of 13 dBi along with bandwidths of 1 GHz. Enhanced antenna performance is achieved through the optimal spacing of antenna elements and a decoupling methodology comprising a well-designed metamaterial unit cell, leading to reduced interference between antenna arrays. The design shows significantly suppressed mutual coupling to be less than −40 dB, a diversity gain that is very close to 10 dB, an envelope correlation coefficient of 0.00012, and a channel capacity loss of 0.147 bit/s/Hz, at 28 GHz. The experimental assessments confirmed these developments, endorsing the suggested design as a robust contender for 5G mmWave communications. Full article

A 4 × 4 wideband millimeter-wave (mmWave) slot array antenna excited by the TE₄₄₀ mode based on the groove gap waveguide is presented in this paper. A vertical waveguide located in the center of the cavity and two ridges are used to excite the TE₄₄₀ mode. In addition, a pair of corrugations acting as the soft surface are added on the top of the array antenna to improve the gain. A 4 × 4 prototype is fabricated and measured. The measured and simulated results are in great agreement. The measured results show that the proposed array antenna achieved an impedance bandwidth (|S₁₁| < −10 dB) of 26.7% from 26.14 to 34.2 GHz, and the maximum gain is 17.7 dBi. The proposed array antenna avoids the complicated feeding network, allowing us to reduce the manufacturing cost. Full article

High-sensitivity and large-scale surveys are essential in advancing radio astronomy, enabling detailed exploration of the universe. A Phased Array Feed (PAF) installed in the focal plane of a radio telescope significantly enhances mapping efficiency by increasing the instantaneous Field of View (FoV) and improving sky sampling capabilities. This paper presents the design and optimization of a novel C-Band Phased Array Feed antenna for the Sardinia Radio Telescope (SRT). The system features an 8 × 8 array of dual-polarized elements optimized to achieve a uniform beam pattern and an edge taper of approximately 5 dB for single radiating elements within the 3.0–7.7 GHz frequency range. The proposed antenna addresses key efficiency limitations identified in the PHAROS 2 (PHased Arrays for Reflector Observing Systems) system, including the under-illumination of the Sardinia Radio Telescope’s primary mirror caused by narrow sub-array radiation patterns. By expanding the operational bandwidth and refining the radiation characteristics, this new design enables significantly improved performance across the broader frequency range of 3.0–7.7 GHz, enhancing the telescope’s capability for wide-field, high-resolution observations. Full article

The localization of unmanned aerial vehicles is an important topic due to several threats near sensitive sites. Localization based on their sounds has been a particular point of interest in past studies for many years. It requires the use of a microphone array. The positioning of the various microphones making up an antenna defines the intrinsic directivity of the array. In this study, a genetic algorithm is used to determine the microphone positions that optimize directivity in a focus direction and for a frequency, by favoring the narrowness of the main lobe and the reduction of the secondary lobes. The optimization leads to several antennas with a 3D structure similar to that designed in a previous study. A method estimating the direction of arrival of a drone was also presented in that study making use of its acoustic signature to enhance the signal-to-noise ratio and thus improving the estimations. In this paper, an improvement to the method is proposed for tracking the drone’s trajectory. Measurements were conducted to compare the drone locations given by the first designed antenna and the one optimized by the genetic algorithm. Performance on the direction of arrival found is characterized in terms of mean error, standard deviation and root mean square error relative to the GPS reference onboard the UAV. An experiment with the optimized antenna has also been conducted with the drone at a great distance to the antenna to characterize the maximal distance for possible estimations of the direction of arrival. Results show that the method used for the direction of arrival estimation can give a mean error below 10° in azimuth and 5° in elevation. The maximum distance between the antenna and the drone for which the method is able to give estimations is between 240 and 340 m. Full article

A compact and wideband beamforming antenna array based on a substrate-integrated coaxial line (SICL) Butler matrix at 60 GHz is proposed in this paper. The cavity-backed patch antenna loading double-ridged horn antenna is designed to enhance a gain of 5.4 dB and a bandwidth of 2.7 GHz. Different phase centers of double-ridged horn elements are formed into a non-uniform array to reduce sidelobes by −7.9 dB. By introducing the defected ground structure (DGS) for a broadband coupler, a rotationally symmetric SICL Butler matrix is designed with a 55–70 GHz bandwidth and compact dimensions of 63 × 65 × 0.512 mm³. To validate the design, a prototype was fabricated and measured. The experimental results show a wideband −10 dB impedance bandwidth of 23.3% (55.4–70 GHz) with measured gains ranging from 15 to 16.1 dBi at 62 GHz. The one-dimensional beam scanning covers ±32°. The simulation and measurement results are in good agreement. Full article

This paper presents a novel multi-layer, dual-band antenna array designed for WLAN and X-band applications, incorporating several innovative features. The design employs a pentagon-shaped radiating element with parasitic strips to enable dual-band operation. A dual-transformed feed network with chamfered feed strip corners minimizes radiation distortion and cross-polarization while introducing orthogonal phase shifts to achieve circular polarization (CP) at the X-band. A Fabry–Pérot structure, strategically placed above the array, enhances gain in the WLAN band. The antenna demonstrates an impedance bandwidth of 1.8 GHz (S₁₁ < −10 dB) at the WLAN band, with 36% fractional bandwidth, and 4.3 GHz at the X-band, with 43% fractional bandwidth. Measured peak gains are 7 dBi for the WLAN band and 6.8 dBi for the X-band, with favourable S₁₁ levels, omni-directional radiation patterns, and consistent gain across both bands. Circular polarization is achieved within 8.5–10.4 GHz. Experimental results confirm the array’s significant advancements in multi-band performance, making it highly suitable for diverse wireless communication applications. Full article

This research presents a high-performance design for a multiple-input multiple-output (MIMO) antenna intended for operation within the 28 GHz band. The four-port MIMO antenna configuration, featuring 1 × 8 series-fed arrays for each port, has demonstrated peak gains of 15.5 dBi and bandwidths of 2 GHz. This improved antenna performance results from carefully optimized antenna spacing and a decoupling approach involving well-designed metamaterial cells, effectively minimizing interference between antenna elements. The system exhibits remarkably low mutual coupling, measuring below −40 dB, with envelope correlation coefficients of 0.00010, diversity gains nearing 10 dB, and a channel loss capacity of 0.11 bit/s/Hz across the frequency spectrum under investigation. Experimental evaluations have confirmed these improvements, establishing the proposed design as a robust candidate suitable for a wide range of millimeter-wave communication systems. Full article