Abstract: This study presents a compact wearable antenna intended for wireless body area network (WBAN) applications. The antenna is realized on a denim textile substrate with overall dimensions of 46 × 55 × 1 mm³, and its performance is evaluated using a commercial full-wave EM solver. Under the S11 < −10 dB criterion, the simulated impedance bandwidths extend from 2.05 to 4.67 GHz and from 5.78 to 8.94 GHz. The design resonates at 2.45 GHz and 7.88 GHz, delivering realized gains of 2.43 dBi and 3.60 dBi at the two bands. The total efficiencies reach 97.62% at 2.45 GHz and 90.0% at 7.88 GHz. These outcomes verify that the suggested structure is a strong candidate for practical wearable implementations.

This paper proposes a Ka-band broadband circularly polarized (CP) antenna array with high cross-polarization discrimination (XPD). The design employs a four-layer stacked dielectric substrate structure, utilizing a 2×2 sequentially rotated (SR) array of substrate integrated cavity (SIC) magnetoelectric dipole elements as the core radiator. A double-layer substrate integrated waveguide (SIW) SR feeding network achieves precise 90[Formula: see text] phase delay at the center frequency, enabling the array to attain 30.33% impedance bandwidth over 23.45-32.02 GHz and 35.52% axial ratio (AR) bandwidth across 22.48-32.19 GHz. A [Formula: see text] multi-layer square-loop array decoupling surface (ADS) is integrated on the topmost dielectric layer of the antenna array. By optimizing the geometry, dimensions of the square loops, and the substrate thickness, this structure generates reflected waves with specific amplitude and phase characteristics, effectively canceling out the coupling waves propagating between the antenna elements. This design significantly suppresses the mutual coupling among the radiating elements, resulting in a XPD better than [Formula: see text] across the operating band. It thereby substantially mitigates the mutual coupling issue commonly encountered in millimeter-wave antenna arrays. Furthermore, the ADS structure enhances gain performance, yielding a peak gain of 12.47 dBic with gain variations below 3 dB throughout 25.95-33.14 GHz. The fabricated array measures [Formula: see text]. The proposed CP antenna array demonstrates significant potential for application in 5G millimeter-wave communication systems.

Tulip tree leaf-shaped microstrip MIMO antenna utilizing the superformula

This work presents a compact printed MIMO antenna specifically designed for portable wireless applications, offering strong isolation between its elements. The antenna consists of two ultra-low-profile inverted-F antenna (IFA) elements placed back to back with a close spacing of just 0.05λ at the resonance frequency (2.4 GHz). To improve isolation, a parasitic structure is strategically positioned between the two IFAs. Additionally, a slot is introduced into the ground plane, which excites an extra resonance, effectively broadening the antenna’s operational bandwidth. The proposed design was successfully fabricated and tested, with measurement results closely matching the simulations. The antenna demonstrates a good impedance bandwidth ranging from 2.28 to 2.85 GHz, maintaining a return loss better than 10 dB, and achieving excellent isolation levels exceeding 40 dB. It also delivers a high peak efficiency of 90% and a realized gain pattern of around 2 dBi over the band of interest. In addition, the inclusion of the parasitic element further enhances the antenna’s performance by promoting pattern diversity and reducing the correlation between radiation patterns, ensuring robust MIMO and diversity characteristics.

ABSTRACT In this letter, a filtering antipodal Vivaldi antenna (AVA) integrating spoof surface plasmon polaritons (SSPPs) and directors, featuring controllable passband characteristics and high gain, is proposed. In the antenna configuration, a set of slots etched along the outer edges of the radiation arms improves the low‐frequency gain, while antenna‐terminal‐loaded semi‐annular directors further enhance the overall gain. The filtering characteristics can be conveniently tuned by adjusting the dimensions of the branched circular metallic patch and the SSPPs structure. A prototype operating from 7.44 to 11.76 GHz was fabricated and experimentally characterized to validate the design. Measurement results demonstrate an impedance bandwidth of 45%, stable in‐band gain with a peak value of 12.14 dBi, and inherent advantages of wide bandwidth and low profile. Compared with conventional AVAs, the proposed design exhibits improved radiation characteristics, achieving both higher gain and superior filtering performance.

ABSTRACT This paper describes the design and implementation of a dual‐layer frequency selective surface (FSS) based dual‐band high‐gain circularly polarized (CP) meander‐shaped monopole antenna for the applications of Wi‐Fi and C‐band. To achieve the final configuration, the design process involves several steps: designing the meander‐shaped antenna, modeling the FSS, circuit analysis, and practical realization. The antenna prototype (electrical dimension: 0.333 λ₀ × 0.266 λ₀, λ₀ at 2 GHz and physical dimension of 50 × 40 mm 2 ) comprises a meander‐shaped strip and a 3 × 3 matrix dual layer periodic FSS embedded under the antenna structure without disturbing the impedance bandwidth. The low‐cost FR4 dielectric substrate is used to design both the antenna and FSS layer. Initially, only the antenna part was designed, which yielded −10 dB impedance bandwidths (IBWs) and 3‐dB axial ratio bandwidths (ARBWs) of 1160 and 600 MHz in the lower band, and 560 and 700 MHz in the upper band, respectively. Without an FSS structure, the peak gains of the antenna are 3.6 dBi (lower band) and 3.8 dBi (upper band). The proposed FSS‐based antenna is fabricated and measured in the microwave test bench. The measured results show 3‐dB ARBWs of 350 MHz (2.35–2.7 GHz) and 600 MHz (3.9–4.5 GHz) with LHCP waves. The measured peak gains are 8 dBi in the lower band and 8.5 dBi in the upper band. With small tolerance, the measured results agree with simulations.

ABSTRACT In this paper, a magneto‐electric dipole (MED) filtering antenna with a novel filter feed network is proposed. The proposed antenna is based on the low‐temperature cofired ceramic (LTCC) process. The MED antenna has an intrinsic radiation null, and a mathematical model of the magneto‐electric dipole is presented to elucidate its working mechanism. An innovative shared‐edge C‐shaped slot structure has been implemented on the ground plane to form a novel filter feed network. The configuration employs two adjacent C‐shaped slots of different dimensions sharing a common edge, achieving significant space reduction. At certain specific frequencies, the energy concentrates in the shared‐edge C‐shaped slots and does not couple to the radiation patches, causing radiation nulls. To analyze this principle, equivalent circuits of the novel filter feed network are provided. The proposed antenna has a total of four controllable radiation nulls with excellent out‐of‐band rejection. For verification, a MED filtering antenna is designed, fabricated, and experimentally validated. The measurement results indicate that the antenna has an impedance bandwidth of 21.7% (11.9–14.8 GHz), an average gain of 5.0 dBi in the passband, and the out‐of‐band suppression level is better than 20 dB.

Compact antennas with broad bandwidth and high gain are essential for modern communication systems, where efficient performance and miniaturization are critical. This work proposes an antenna design incorporating a driver, reflector, and director to achieve these objectives. The driver and director feature conical shapes for bandwidth enhancement, while the reflector adopts a partial spherical shape to promote a directive radiation pattern and to enhance the realized gain toward the director while minimizing the antenna’s electrical size, a kr of 1.05. The measured −10 dB impedance bandwidth of the antenna is 64%. The average realized gain is 8.6 dBi in the direction of the director. These results demonstrate the effectiveness of the proposed design in achieving a compact, high-gain, broadband antenna suitable for advanced communication applications.

A compact high-gain antipodal Vivaldi antenna with ultra-wideband (UWB) performance ranging from 1 GHz to 25 GHz is proposed and demonstrated. The antenna features two sets of tapered exponential slots along the flare edges to enhance low-frequency impedance matching and broaden the operating bandwidth. To address high-frequency gain degradation, a rhombus-shaped metamaterial array is embedded within the tapered slot region, effectively improving radiation directivity and suppressing gain roll-off without enlarging the antenna footprint. Full-wave simulations and experimental measurements confirm that the proposed antenna achieves a well-matched impedance bandwidth from 1 to 25 GHz, with a peak gain of 15.84 dBi. Notably, the gain remains consistently above 14 dBi in the high-frequency region, verifying the effectiveness of the embedded metamaterial structure. The proposed design successfully balances wideband operation, high gain, and compact form factor, offering a promising solution for space-constrained UWB applications in communication, sensing, and imaging systems.

The emergence of sixth-generation (6G) wireless networks demands broadband antennas capable of ultra-high data throughput and seamless global connectivity. This study presents a genetic-algorithm (GA) optimization framework to enhance antenna performance, focusing on patch dimensions, ground-plane size, and feed position. Full-wave electromagnetic simulations were performed in CST Microwave Studio and ANSYS HFSS, employing defined mesh sizes, solver types, and boundary conditions to ensure accurate evaluation. The GA-based optimization achieved an impedance bandwidth of 3.2–6.1 GHz, a peak gain improvement of 2.8 dB, and radiation efficiency exceeding 92%, outperforming conventional gradient-based tuning. The optimized antenna exhibited stable S-parameters and an omnidirectional radiation pattern across the target spectrum, confirming reliable operation at high frequencies. This approach highlights the advantages of evolutionary algorithms in enabling efficient, manufacturable, and high-performance broadband antenna designs for next-generation wireless systems. Beyond immediate 6G applications, the methodology can be extended to millimeter-wave and terahertz antennas, supporting continued innovation in ultra-reliable, high-capacity wireless communications.

This paper presents the design and fabrication of a slant-polarized monopulse array antenna featuring a cosecant-squared radiation pattern for accurate target tracking. The proposed 2 × 8 microstrip array employs a modified proximity coupling scheme and incorporates metallic walls to reduce mutual coupling. A strategically placed ground plane enhances the gain, suppresses the back lobe, and improves isolation from the surrounding environment. The amplitude and phase excitations are optimized with a genetic algorithm that accounts for mutual coupling to synthesize the desired cosecant-squared pattern. A rectangular 180-degree hybrid coupler is integrated to enable monopulse operation in the azimuth plane, thereby improving tracking performance. Measurement results of the fabricated prototype demonstrate a 34% impedance bandwidth (3.8–5.4 GHz), a peak gain of 13.05 dBi, a sidelobe level of 13 dB, a null depth of 24 dB, and an elevation plane beamwidth of 24° at the center frequency, all of which align closely with simulation results. The measured radiation pattern accurately follows the ideal cosecant-squared curve.

ABSTRACT This article presents a novel compact printed monopole antenna with a gun‐shaped design, developed for multiband operation targeting WLAN, WiMAX, and X‐band applications. The antenna features a gun‐shaped radiating patch integrated with two L‐shaped structures and multiple stubs, which are optimized to support five distinct frequency bands. By introducing a rectangular cut into the patch and a rectangular slot, enhanced multiband performance with good impedance matching and radiation characteristics is achieved. The antenna is fabricated on a low‐cost, low‐profile FR4 substrate with a dielectric constant of 4.4, a loss tangent of 0.02, and a thickness of 0.8 mm. It has a compact overall size of 18 × 18 × 0.8 mm 3 and operates across the following frequency bands: 2.3–2.84, 3.4–3.7, 4.8–5.2, 6.2–7.1, and 7.9–8.2 GHz, all with reflection coefficients (S 11 ) better than −10 dB. The measured peak gains at 2.4, 3.6, 5.0, 6.5, and 8.0 GHz are 2.4, 2.8, 2.9, 4.1, and 2.8 dBi, respectively. The antenna achieves impedance bandwidths of 22.5%, 8.33%, 8.00%, 13.84%, and 3.75% at the respective resonant frequencies of 2.4, 3.6, 5.0, 6.5, and 8.0 GHz. It also exhibits high radiation efficiency, exceeding 90% across all bands. A close agreement is observed between the simulated and measured results, confirming the antenna's suitability for multiband wireless communication systems.

This paper presents a novel electromagnetic metasurface-integrated antenna design that utilizes periodic structures to significantly enhance gain stability across the entire ultra-wideband (UWB) frequency range (3.1–10.6 GHz). Unlike conventional approaches that position metasurfaces as separate external elements, the proposed design directly integrates the metasurface into the antenna structure. This integration not only reduces spatial requirements but also improves overall compactness, making the antenna more practical for real-world implementation. The proposed antenna demonstrates consistent gain performance and a highly uniform broadside gain response throughout the full UWB spectrum. These advantages effectively address the persistent issue of gain fluctuation found in conventional UWB antennas, which is critical for maintaining stable communication performance. Furthermore, this work introduces a systematic design methodology that balances wideband impedance matching with enhanced radiation characteristics, advancing the application of metasurface technologies in antenna engineering. The proposed technique shows promising potential for future wireless communication systems and precision indoor positioning applications.

Wireless power transfer via RF/microwave rectifiers has emerged as a sustainable solution to the energy requirements of low-power devices. In this study, a novel four-parallel-shunt-diode ultra-wideband rectifier is proposed to enable wireless power transfer in the sub-6-GHz 5G bands. The proposed circuit maintains a power conversion efficiency (PCE) above 50% across the 1.6–5.1 GHz frequency range at 10 dBm input power and also achieves an efficiency above 50% at 3 GHz for input powers between 1 dBm and 16 dBm. Designed and fabricated on a low-cost FR4 substrate, the rectifier achieves a maximum power conversion efficiency of 76% at 2.9 GHz with a 10 dBm input power. Furthermore, a wideband impedance analysis is performed, taking into account the packaging parasitics of the HSMS-2860 diodes used in the study. Despite the use of a lossy substrate such as FR4, the proposed four-parallel-shunt-diode topology improves impedance stability and provides impedance matching over both a wide input-power range and a wide frequency band when compared with single- and double-diode structures reported in the literature.

This paper presents a compact magneto-electric dipole (MED) antenna optimized for wideband circularly polarized (CP) radiation for 5G applications. It incorporates a staircase-shaped electric dipole with trimmed corners to excite orthogonal modes for enhanced CP performance. The proposed single-layer MED antenna achieves a wide-impedance bandwidth ( dB, – GHz) and CP bandwidth ( dB, – GHz) with a compact footprint of . There is a symmetrical radiation pattern with a co-to-cross polarization ratio dB and a stable gain of dBi. An equivalent circuit model is optimized via particle swarm optimization (PSO). The optimized MED antenna is utilized to investigate various CP-MIMO configurations and wideband sequential arrays. Next, a CP-MIMO antenna system is developed, employing polarization diversity in parallel and mirror configurations. Isolation is improved by etching a ground slot between the MED elements, yielding isolation levels of below dB and dB, respectively. Further, a CP-MIMO configuration is designed and evaluated. This arrangement demonstrates an envelope correlation coefficient (ECC) of and a diversity gain of approximately 10 dB across the operating bandwidth. Finally, a sequential array is designed that applies a sequential rotation and phase excitation to MED elements for high-gain CP 5G communications. Here, various array sizes are evaluated, with an MED array providing CP radiation ( dB) from 20 to 30 GHz with enhanced impedance and axial ratio bandwidths and stable gain with a peak value of dBi.

The increasing demand for compact, high-performance antennas capable of supporting multiple wireless communication standards has driven the development of multiband microstrip antennas. This research presents the design, simulation, and optimization of a multiband microstrip patch antenna operating at 2.4 GHz, 3.5 GHz, and 5.3 GHz, targeting applications in Wi-Fi and WLAN systems. The antenna structure is designed and analyzed using CST Microwave Studio, leveraging its full-wave 3D electromagnetic solver to evaluate key performance metrics including reflection coefficient (S11), gain, bandwidth, and radiation characteristics. To enhance the antenna's performance and reduce the design iteration cycle, support vector regression (SVR), a supervised machine learning technique, is employed. SVR models the nonlinear relationship between the antenna's geometric parameters and its performance outcomes, enabling efficient prediction and optimization. A dataset of 1844 samples is generated through parametric simulations in CST, and the SVR model—using a radial basis function kernel with C = 300, ε = 0.00000000025, and γ = 0.5—is trained to predict return loss and gain across the three target frequencies. The optimized antenna design achieves improved impedance matching, gain enhancement, and bandwidth control at all three frequency bands. Power transfer efficiency exceeds 96% in each band. The results demonstrate that the integration of SVR into the antenna design workflow provides a robust, data-driven approach to achieving multiband performance with high efficiency, making it suitable for next-generation wireless communication systems. Received: 11 August 2025 | Revised: 15 October 2025 | Accepted: 27 November 2025 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement Data are available from the corresponding author upon reasonable request. Author Contribution Statement Nejat Abdulwahid Hassen: Conceptualization, Methodology, Software, Validation, Formal analysis, Investigation, Data curation, Writing - original draft, Visualization, Supervision. Adomeas Asfaw Tafere: Conceptualization, Methodology, Software, Validation, Resources, Data curation,Writing - review & editing, Visualization,Supervision. Murad Ridwan Hassen: Conceptualization, Methodology, Software, Formal analysis, Investigation, Resources, Writing - original draft, Visualization, Supervision, Project administration. Tsega Asresa Mengistu: Conceptualization, Software, Validation, Resources, Writing - review & editing, Visualization, Supervision. Mekete Asmare Huluka: Conceptualization, Software, Validation, Resources, Writing - review & editing, Visualization, Supervision. Amsalu Tessema Adgeh: Conceptualization, Software, Formal analysis, Resources, Writing - review & editing, Visualization.

In this article, a dual-port MIMO antenna has been investigated with stable dual radiation performance for 5G wireless broadband services. Here, two antenna sections, consisting of a pair of monopole strips, are hybridized with independent excitation units, achieving effective bandwidth, good port isolation and dual radiation performance. The design embodiment linked to a cross-coupled ± 45 ∘ radiators at the top and a reflector at the bottom. All independent antenna units are excited by a referential balun, which acts like an impedance transformer and behaves like a dipole resonator. The excitation in each antenna units asserts a stable duality boresight ± 45 ∘ radiation with a maximum backlobe suppression. The performance merits of the proposed antenna design have been validated on a prototype model, which operates at Port-1 from (2.6 to 4.06) GHz with 43.84% 10 dB impedance bandwidth and at Port-2 from (2.6 to 4.04) GHz with 43.37% 10 dB impedance bandwidth, with consistent port isolation >25 dB in the operating band, 9.07 dBi as peak realized gain and radiation efficiency of (87–89)%, which can be leveraged in 5G wireless applications.

ABSTRACT A low-profile broadband magneto-electric dipole (MED) filter antenna array is presented. This array simplifies design complexity by utilizing the MED antenna’s inherent radiation nulls. Broadening the impedance bandwidth is achieved by trimming the rectangular corners of each 1/4-sector metal patch. Additionally, L-shaped slits enhance suppression at higher frequencies. The antenna measures 0.86λ0 ×0.86λ0 ×0.15λ0 and offers an impedance bandwidth of 50.2%(22.81–38.10 GHz). It maintains a consistent in-band gain with a peak of 8.3dBi and demonstrates out-of-band rejection exceeding 12 dB on both sides. For enhanced gain, a 4 × 4 filtered antenna array has been fabricated and tested. The array exhibits an impedance bandwidth of 48.3% (19.05–31.20 GHz). The in-band gain exceeds 19dBi, and the radiation efficiency stays above 85%. The array also showcases robust out-of-band rejection, making it efficient and practical to implement.

This paper presents the design and performance evaluation of a compact dual-band implantable antenna (Rx) operating at 1.32 GHz and 2.58 GHz for biomedical applications. The proposed antenna is designed to receive power and data from an external transmitting (Tx) antenna operating at 1.32 GHz. The measured impedance bandwidths of the Rx antenna are 190 MHz (1.23–1.42 GHz) and 230 MHz (2.47–2.70 GHz), covering both the power transfer and data communication bands. The wireless power transfer efficiency, represented by the transmission coefficient (), is observed to be −40 dB at a spacing of 40 mm, where the Rx is located in the far-field region of the Tx. Specific Absorption Rate (SAR) analysis is performed to ensure electromagnetic safety compliance, and the results are within the acceptable exposure limits. The proposed antenna achieves a realized gain of −25 dB at 1.32 GHz and −25.8 dB at 2.58 GHz, demonstrating suitable performance for low-power implantable medical device communication and power transfer systems. The proposed design offers a promising solution for reliable biotelemetry and wireless power transfer in implantable biomedical systems.

This article presents the design of a dual-mode resonant, dual-band textile microstrip patch antenna for bent sensing applications. The antenna has a simple, slit-perturbed circular sector patch configuration. Unlike traditional single-mode resonant bending sensor antennas, dual-mode resonance brings a unique dual-band sensing characteristic to textile antennas. It effectively covers 2.45 GHz and 5.8 GHz Industrial, Scientific and Medical (ISM) frequency bands. Experimental results demonstrate that the proposed antenna achieves −10 dB impedance bandwidths of 1.4% (2.43–2.465 GHz) and 2.4% (5.775–5.915 GHz), with maximum peak gains of 8.8 dBi and 9.1 dBi, respectively. As experimentally validated on flannel substrates, the antenna achieves maximum bent sensing sensitivities of 1.1 MHz/mm and 1.78 MHz/mm at 2.45 GHz and 5.8 GHz bands, respectively. Furthermore, the antenna is able to provide stable E-plane broadside radiation patterns in bending situations. It would be an ideal candidate for radio frequency identification (RFID), health monitoring systems, and flexible communication applications.