ABSTRACT The features of both the tag and reader in a Radio Frequency Identification (RFID) system are preferred collectively for special vehicle applications such as defense systems and traffic enforcement. This work presents a novel multifunctional antenna performing both tag and reader operations in a single unit by altering the switching status. An asymmetrical coplanar waveguide (CPW) with a meander-shaped dipole antenna is designed for a circular polarization (CP) radiation. The reader antenna is fed by a 50 ohm microstrip line, while a rectangular loop is used as a matching network for tag excitation. PIN diodes are incorporated at both feeding lines for switching between the two operations. The antenna exhibits an axial ratio bandwidth (ARBW) of (0.83–0.98) GHz for the reader function and from (0.854–0.984) GHz for the tag function. The 3 dB beamwidth and axial ratio beamwidth (ARbw) attain 135° and 80°, respectively, while performing as a reader, and correspondingly 135° and 55°, respectively, while performing as a tag. The maximum measured reading range is 6.2 m in the H-plane. The CP characteristics of the proposed design are analyzed using field component transformation and found to be in close agreement with the simulation response. A prototype of the proposed structure is fabricated, and the experimental results align with the simulated results.

Next-generation internet of things (IoT) wireless electronics require antennas that are conformal, transparent, and electromagnetically efficient, yet these attributes form an impossible trinity. Here, we realize the first Ti3C2Tx MXene–based conformal, transparent, and high-performance antenna through an optimized nanoimprint lithography-blading technique. Nanoimprinted MXene grid transparent conductive film (TCF) achieves an exceptional balance of low sheet resistance (4.32 ohms per square) at high transmittance (~89.1%) with promising flexibility. Two representative scenarios in IoT networks are selected to demonstrate the versatility of this TCF. For personal devices, the efficient MXene transparent dipole antenna enables a quasi-transparent wireless wearable device for long-distance and real-time communication (>30 meters). For fixed infrastructure, MXene-based digital coding metasurface enables high-quality wireless communication, maintaining a low bit error rate (~0.15%) even in a curved state. This work establishes MXene as a versatile platform that successfully merges conformal transparency and high electromagnetic performance, paving the way for next-generation imperceptible IoT wireless systems.

There is a substantial demand for lightweight, low-profile, and conformal antenna integration on the wing platforms of unmanned aerial vehicles (UAVs). This paper presents an S-band (2–4 GHz) flexible conformal metasurface array antenna based on a highly conductive graphene-assembled film (GAF). The main contributions of this work are twofold. First, flexible and highly conductive GAF is used as the conductor together with a flexible polyimide (PI) dielectric substrate to form a GAF-based wing-conformal antenna configuration with a low-profile, lightweight, and easily conformal performance. Second, a GAF conformal antenna element is developed by combining a dipole antenna with a directive and reflective frequency selective surface (FSS), achieving effective control of the beam and stable directional radiation at 2.4 GHz. Full-wave simulations using CST Studio Suite show that the directive FSS narrows the feed beam, whereas the reflective FSS redirects and narrows the H-plane radiation. The simulated results show that the integrated wing-conformal antenna operates over 2.19–2.65 GHz and achieves a gain of 4.65 dBi at 2.4 GHz. The measurement results indicate that the GAF conformal antenna and 1 × 4 GAF conformal array antenna shows measured reflection coefficients below dB at 2.4 GHz and effective adjacent-element isolation. In addition, simulated results indicate that the GAF array antenna can perform beam scanning within the ±40° range, verifying the beam-control capability of this structure for UAV forward communication. Overall, this work highlights the feasibility of using GAF as a conductive material for both a high-efficiency radiator and an FSS beamforming structure, offering a practical material and design approach for lightweight, low-profile, and wing-conformal airborne array antennas.

A novel approach of investigating nature inspired antenna configuration with an uniquely featured artificial magnetic conductor (AMC) has been proposed. A palmately lobed leaf-like pattern asserted to develop correlative reciprocal dipole antenna (CRDA) achieving effective radiation potential. The reciprocity of dipole antenna elements are impedance matched with 50-Ω cut-away balun exciter. An intuitive inhomogeneously engineered bicentric (IEB-AMC) reflector enhances impedance and radiation parameters. The IEB-AMC arrangement consists of periodic assembly of bicentric AMC unit cells whose relative orientation of each discrete elements are strategically configured with asymmetrical non-uniform angles. The relative phase of each unit AMC cells exhibits invariance with reference to the relative angle of orientation and delivers consistent AMC zero phase cross-over resonance at 6.4 GHz. The unit cell configuration asserts phase invariance properties at all angles. A prototype antenna of dimension 60 mm × 60 mm × 9 mm has been fabricated to validate experimentally on its functionality. The antenna operates from (6.3 – 7.3) GHz with a peak realized boresight radiation gain of 11.06 dBi, stable dual radiation patterns, and radiation efficiency >90%. The simulated and measured performances exhibit excellent correlation for Wi-Fi 7 GHz/IEEE 802.11be systems.

This work proposes a polarization-insensitive scalable wide-angle metasurface array for highly efficient ambient energy harvesting in the 5.8 GHz Wi-Fi band. Inspired by dipole antenna principles, we design an asymmetric planar orthogonal dipole-based metasurface featuring monolithic integration of Schottky diodes (HSMS-2860) at unit cell feed gaps. This novel direct-impedance-matching strategy eliminates conventional matching networks, reducing energy conversion losses while enabling 99% radiation-to-AC efficiency across all polarization angles at 5.8 GHz. The coplanar architecture interconnects metasurface unit cells via inductors, simultaneously establishing low-loss DC channels and suppressing RF leakage. Fabricated as a 5 × 5 array, the prototype achieves 77.9% peak RF-to-DC efficiency with polarization insensitivity at an incident power of 25 dBm. Furthermore, with incident powers of 15 dBm and 20 dBm, the proposed metasurface array attained RF-to-DC conversion efficiencies exceeding 40% and 60%, respectively. This result indicates that the array is capable of achieving high energy harvesting efficiency across a broad power range. This scalable, drill-free, and polarization-insensitive design demonstrates strong potential for harvesting ambient RF energy in real-world multipath environments.

Continuous introduction of advanced optimization algorithms promotes the development of electromagnetic (EM) technology in radar and communication systems. Wideband antenna design within a given space and wideband array pattern synthesis, especially in the scenario of strong mutual coupling, are two typical challenging electromagnetic problems. In this paper, a nature-inspired algorithm, i.e., the water cycle algorithm (WCA), is introduced to resolve the above two EM problems. Two typical wideband antennas, i.e., the dual-band E-shaped microstrip antenna and the typical magnetoelectric (ME) dipole antenna, are designed on the basis of the established WCA-based antenna design scheme. Compared with the well-known algorithms that have been introduced in antenna design, including the differential evolution (DE) algorithm and the gray wolf optimizer (GWO), better results can be achieved with WCA. In the sequel, a WCA-based low peak sidelobe level (PSLL) pattern synthesis is implemented based on a uniformly spaced 27-element folded fractal ME dipole array antenna with mutual coupling as high as −10 dB, the results of which further validate the superiority of WCA in array pattern synthesis and demonstrate the value of this application innovation.

This paper presents a compact, wideband, and frequency-reconfigurable Magneto-Electric Dipole (MED) antenna designed for sub-6 GHz 5G New Radio (NR) and Industrial, Scientific, and Medical (ISM)/ Wireless Local Area Network (WLAN) applications. The proposed antenna utilizes an aperture-coupled excitation mechanism integrated within a multilayer FR4 structure, featuring complementary electric and magnetic dipole elements that are optimized through a four-step evolutionary design process. The final configuration achieves a simulated broad Impedance Bandwidth (IBW) of 2.24–4.55 GHz in the all-diodes-off state, while maintaining stable broadside radiation, a peak gain of over 7.7 dBi, and a radiation efficiency of up to 94.2%. Frequency reconfigurability is achieved through the use of six strategically placed PIN diodes, which selectively modify the current distribution on the microstrip feed line by coupling six rectangular stubs. Multiple diode-controlled switching states enable wide tunability from 1.79 GHz to 4.41 GHz, providing support for more than twelve major 5G NR bands, including n7, n30, n34, n38, n40, n41, n48, n53, n65, n77, n78, n90, n95, and n97, as well as ISM/WLAN services. Simulated and measured results exhibit strong agreement across all states, with peak gains ranging from 7.06 to 7.82 dBi and radiation efficiencies between 65.6% and 96.1% (see Table 3), confirming the robustness of the aperture-coupled and diode-integrated MED architecture. Compared to recent state-of-the-art MED and reconfigurable MED antennas, the proposed design demonstrates a wider tuning range, competitive gain, and reduced structural complexity while maintaining a compact volume of 0.48λ₀ × 0.48λ₀ × 0.11λ₀ at 3.5 GHz. These characteristics highlight its suitability for compact 5G terminals, small-cell base stations, reconfigurable wireless systems, and multi-standard communication platforms.

This paper presents the design and performance analysis of a high-gaindipole antenna using a partially reflective Meta surface (PRMS) layer and a parasitic director element operating at 3.2 GHz in the S-band. Conventional dipole antennas exhibit low gain and bidirectional radiation, which limits their efficiency in modern communication systems. The existing work on high-gain broadband dipole antennas using PRMS layers demonstrates gain improvement through Fabry–Perot cavity formation. However, further enhancement in directivity and gain is required for advanced applications. In the proposed design, a planar reflector, PRMS layer implemented using a frequency selective surface (FSS), and a rod-shaped director are integrated with the dipole antenna. The PRMS layer enables partial reflection and forms a resonant cavity, while the director focuses radiation in the forward direction. The antenna is simulated using ANSYS HFSS, and the results show a return loss of approximately –17 dB, VSWR close to unity, and gain around 7–8 dB. The proposed design achieves improved directional radiation and enhanced gain compared to the existing model, making it suitable for S-band wireless and satellite applications.

The insulation condition of high-voltage equipment can be determined by measuring partial discharge (PD), which is an important indicator in insulation degradation. One of the PD detection methods that can be used is to use antennas as sensors in detecting electromagnetic waves generated from PD activities, especially in gas insulated switchgear (GIS) systems. This study focuses on designing and testing dipole antennas in the ultra-high frequency (UHF) frequency range of 300 Mhz-3 GHz to detect PD signals in GIS. Previous studies on dipole antennas with dimensions of 66×15 mm have reported a bandwidth of 336 MHz and a return loss of -22.4 dB at 1.3 GHz. The antenna was fabricated using an FR4-epoxy substrate with a thickness of 1.6 mm, a substrate radius of 102 mm, and a gap distance of 2 mm. Optimization of the antenna length and width significantly improved performance characteristics. Simulation results show that a dipole antenna with dimensions of 35×40 mm antenna produced a wider bandwidth of 989 MHz with a return loss of −28.47 dB at 1.4 GHz. Experimental validation using vector network analyzer (VNA) and PD testing on GIS confirmed that the optimized dipole antenna effectively detected PD activity at a voltage level of 16 kV.

ABSTRACT This paper investigates the NFF shaping in wideband scenario via SOCP. In particular, the proposed method defines a frequency‐weighted matrix to balance the gain differences across the wideband frequency region during the optimization procedure. Meanwhile, for the continuous shaped fields, the desired focus is decomposed into a set of uniform multiple focuses with reasonable position offsets based on the principle of linear superposition. Typical scenarios of single and multiple focus fields, and continuous shaped fields including “一,” “X,” and “Z”‐shaped field are successfully realized based on typical wideband magneto‐electric (ME) dipole antenna, which demonstrate the effectiveness of the proposed approach in wideband arrays.

ABSTRACT This letter proposes a low‐profile magneto‐electric (ME) dipole antenna for in‐band full‐duplex (IBFD) systems. The designed antenna consists of a crossed ME dipole with cross‐shaped copper pillars serving as magnetic arms. One polarization is fed via an H‐shaped slot coupled by a T‐shaped power divider at one port. The other port adopts a differential feeding setup, utilizing an external 180° power divider. By integrating hybrid decoupling techniques, the prototype achieves a port‐to‐port isolation exceeding 45 dB within an overlapping −10 dB impedance bandwidth of 46.8% (1.70–2.73 GHz). By enlarging the dipole dimensions and optimizing current distribution through the cross‐shaped copper pillar structure, the profile height is reduced from 0.25 λ₀ in conventional designs to 0.13 λ₀. Measurement results show that Port 1 exhibits a gain range of 7.2–9.5 dBi, while Port 2 achieves 6.3–7.7 dBi. Additionally, the measured radiation efficiency exceeds 70% across the 1.70–2.73 GHz band. These characteristics make the antenna a promising candidate for IBFD base station systems.

To evaluate the performance of a printed log-periodic dipole antenna (PLPDA) in outdoor environments, we present unmanned aerial vehicle (UAV)-based antenna measurements conducted in the far-field region. Non-tethered UAV flight operations were achieved by configuring commercially available UAVs separately as a transmitter (TX) and as a receiver (RX). UAVs configured in non-tethered mode provide flexibility in terms of altitude maintained by the UAV from the ground level. The TX section of the UAV consists of a portable signal generator and a PLPDA configured to transmit signals with an output power of +15 dBm at 0.8 and 3.5 GHz. Similarly, the RX section of the UAV is equipped with a real-time spectrum analyzer and an identical PLPDA. Using these two UAVs in TX and RX modes, the radiation pattern of the PLPDA was obtained in the azimuth plane. Since two identical PLPDAs were used, the realized gain of the PLPDA is evaluated using the two-antenna gain method. The test scenario involved the TX UAV hovering at the center while the RX UAV followed a circular trajectory around it. A comparison between the UAV measurements, anechoic chamber measurements, and simulated data demonstrates good agreement, validating the reliability of the measurements.

One of the strongest electromagnetic engineering approaches for enhancing antenna performance is the use of photonic crystal (PhC) substrates. This technique can be efficiently applied to antenna design and offers notable advantages, such as gain improvement, increased bandwidth, and frequency-dependent beam scanning. In this paper, a bow-tie dipole antenna has been developed for terahertz operation over the 0.39–1.3 THz band, presenting a novel structure capable of producing strong ultra-wideband (UWB) field enhancement within its feed gap. The feed gap between the two metallic arms has a slot width of 1.24 λ0 (λ0 is the wavelength in free space at a center range of 0.8 THz), which facilitates the generation of an enhanced electric field. The PhC substrate enables surface-wave control through dispersion engineering, thereby enhancing the radiation efficiency of the antenna. The proposed antenna exhibits a radiation efficiency of approximately 73–93% over the entire UWB frequency band. Furthermore, the PhC substrate antenna achieves a maximum gain of 21 dB, exceeding that of a homogeneous-substrate THz bow-tie antenna by at least 3.3 dB. The results indicate that the antenna achieves |S11| < −10 dB impedance matching over the bandwidth of 105.9%, ranging from 0.4 to 1.3 THz. The proposed bow-tie dipole antenna integrated with a PhC substrate demonstrates a wide beam-scanning capability from −54° to +74° across the 0.39–1.16 THz band, while maintaining a compact footprint of 14.9 λ0 × 22.4 λ0. This combination of wide scanning, broad bandwidth, and ultra-low profile represents a notable advancement in the development of compact THz radiating structures.

Abstract This study presents the development of a 3D-printed, wideband, dual-polarized magneto-electric dipole antenna. The proposed antenna demonstrates exceptional cross-polarization isolation (XPI) between its two mutually orthogonal RF ports, achieved through innovative feeding probes, specifically an inverted $\Gamma$ -shape and a conventional $\Gamma$ -shape probe. The analysis reveals that misalignment between probes can impair XPI; this phenomenon is systematically examined through electromagnetic full-wave simulations. A practical remedy is provided using four plastic rods strategically positioned through the probes and posts. Measurements indicate that XPI exceeds 50 dB across the common operating frequency range of 3.05–4.13 GHz (30%). The maximum realized gain is approximately 7.9 dBi, with a nearly flat response and stable radiation patterns across both ports throughout the bandwidth. The proposed antenna offers a cost-effective, 3D-printed design, wideband radiation performance, and exceptional port-to-port isolation, demonstrating significant potential for full-duplex wireless communication and ICAS applications.

This work proposes a tri-band shared-aperture antenna array with three wide bands, covering the 5G mid-band and the 6G centimetric band, which is a promising candidate for future 6G base station antennas. The challenge of suppressing interferences, including scattering and coupling, in the tri-band array is holistically addressed across wide bands. Guided by characteristic mode analysis (CMA), a segmented spiral radiator is efficiently developed to mitigate scattering and coupling at high frequencies while preserving radiation performance at low frequencies. Compared to a conventional tube radiator, the proposed spiral exhibits a reduced radar cross-section (RCS) over an ultra-wide range of 4.7-21.5 GHz (128.2%). With the aid of serial resonators, impedance matching of the segmented-spiral-based dipole antenna is achieved across the low band (LB) of 3.05-4.68 GHz (42.2%), spanning the 5G band 3.3-4.2 GHz. Moreover, suppressors are placed near the LB ports to further reduce the cross-band coupling. Middle band (MB) and high band (HB) antennas operate in 6.2-10.0 GHz (46.9%) and 10.0-15.6 GHz (43.8%), respectively, collectively covering the anticipated 5G-Advanced and 6G centimetric band of 6.425-15.35 GHz. Both the MB and HB antennas employ a planar magnetoelectric (ME) dipole structure, which prevents common-mode resonances in the LB and MB, and mitigates the scattering from the MB antenna in the HB. In this tri-band array, radiation patterns remain undistorted across the LB, MB, and HB, and the isolation between any two ports exceeds 20 dB over all three bands.

Circularly polarized magneto-electric dipole antenna with microstrip line cross aperture-coupled excitation

This paper presents a multifunctional reflectarray antenna (MRA) featuring selective in-band switchable polarization and out-of-band radar cross-section (RCS) reduction. To mitigate the strong out-of-band reflections inherent in conventional reflectarray antennas, a frequency-selective rasorber is designed as the top-layer metasurface, providing a transmission passband for in-band operation and dual broadband absorption bands for out-of-band RCS reduction. The bottom-layer metasurface is a 1-bit polarization conversion metasurface designed to reflectively convert incident linear polarization into left-handed circular polarization (LHCP), right-handed circular polarization (RHCP), or maintain the incident linearly polarized state. By integrating a dual-polarized bow-tie dipole antenna, the proposed MRA achieves a compact profile of 1.56λ0 without compromising the radiation performance. A prototype of MRA is fabricated and measured, demonstrating good agreement between simulation and experimental results. Experimental results show that for both the LHCP and the RHCP, the MRA achieves a peak realized gain of 16.2 dBic at 7 GHz, with an aperture efficiency of 29.38%, and a 1 dB gain bandwidth of 13.72%. For linearly polarized radiation, the peak realized gain reaches 16.4 dBi at the same frequency, accompanied by an aperture efficiency of 30.77% and a 1 dB gain bandwidth of 12.89%. Furthermore, the monostatic RCS is reduced by more than 10 dB in two frequency bands: 3.3–6.3 GHz (62.5%) and 8.8–11.8 GHz (29.13%).

Textile platforms that simultaneously enable motion sensing and energy harvesting are vital for self-sustained personalized healthcare and autonomous Internet of Things (IoT) applications. Textile-based triboelectric nanogenerators (T-TENGs) are widely investigated for biomechanical energy harvesting and self-powered sensing; however, their sensing outputs are inherently dependent on motion speed, which complicates the accurate detection of human body motion. Here, we present a multifunctional embroidered-based TENGtenna capable of both radio frequency motion sensing and triboelectric energy harvesting on a textile platform. A sinusoidal-shaped dipole antenna was embroidered on Lycra-nylon fabric using highly conductive fibers, which can effectively provide sensing outputs determined solely by strain rather than the speed of motion, unlike conventional TENG-based sensing that requires complex calibration algorithms. The sensing performance was systematically validated under controlled mechanical loading (0.2–3 Hz) using a Zwick Roell testing system, as well as in real-time human trials including arm bending, knee bending, cycling, and treadmill walking at variable speeds. The electromagnetic safety of the antenna was verified through HFSS simulations, with the calculated specific absorption rate (SAR) values remaining within international safety limits. For energy harvesting, complementary electrospun nanofibers of thermoplastic polyurethane (TPU) and Poly(vinylidene fluoride) (PVDF) were deposited on fabric to make flexible, stretchable, and breathable triboelectric layers, which achieve enhanced triboelectric performance under biomechanical deformation (0.5–2 Hz). The demonstrated dual functionality, strain-based RF sensing and triboelectric energy harvesting, within a single embroidered textile architecture establishes a scalable pathway toward conformal, mechanically compliant, and energy-autonomous wearable systems for continuous human motion monitoring and next-generation IoT applications. • An embroidered textile antenna integrated with electrospun nanofibers enables speed-independent RF-based human motion sensing and triboelectric energy harvesting. • Strain-induced resonance shifts provide robust motion tracking across a wide frequency range, while nanofiber contact electrification delivers stable biomechanical energy output. • The single, breathable textile platform demonstrates durable performance under cyclic deformation, which offers a scalable route toward energy-autonomous wearable sensing systems. • Electromagnetic exposure analysis shows SAR values compliant with IEEE C95.1-2020 and ICNIRP EMF guidelines to validate user safety.

This paper compares silver (Ag) and aluminum (Al) as patch materials for a microstrip dipole antenna to examine how their electrical conductivities affect electromagnetic radiation performance. Both antennas were designed with identical geometrical and substrate parameters using the Finite-Difference Time-Domain (FDTD) method, varying only the patch material. Simulation results show that the resonant frequencies are 2.4700 GHz for Ag and 2.4649 GHz for Al, with excellent VSWR values 1.0839 and 1.0836 and return loss below –27 dB. Both materials exhibit reflected power below 0.2% and have nearly identical radiated power, namely 0.3647 W for silver (Ag) and 0.3646 W for aluminum (Al). Overall, silver and aluminum demonstrate almost identical radiation characteristics. Silver offers slightly better conductivity, while aluminum provides similar efficiency at lower cost, making it a practical alternative for lightweight and economical microstrip antenna applications.

One of the key operating bands for wireless communication is the VHF (Very High Frequency) band. This band accommodates a variety of applications within its operational frequency range, such as Land Mobile, FM/TV Broadcast, amateur radio etc. Consequently, it is essential to explore Antenna designs that are suitable for this band. This paper concentrates on the dipole folded antenna design at 100 MHz frequency. Simulations, fabrication, and testing have been conducted. This paper presents a novel model, along with the implementation of a folded dipole antenna optimized for military vehicular applications in the VHF band (30–300 MHz). The proposed antenna achieved a measured resonant frequency of 98 MHz, a return loss of –28 dB, and a VSWR of 1.07, which closely corresponds with both simulated and theoretical results. Furthermore, the antenna demonstrates a wide operational bandwidth of 12 MHz while maintaining a compact structure suitable for vehicles (~2.9 m). This combination of enhanced impedance matching, stable bandwidth, and field-ready fabrication distinguishes it from traditional folded dipole designs used in the VHF range. We have compared the S 11 plots of the simulated results and the fabricated results. The characteristics of a folded dipole antenna are comparable to those of a dipole Antenna, and HFSS software can be utilized to design and assess it. At the conclusion of the investigation, the simulated return loss result for the folded dipole antenna aligns well.