Advanced Electromagnetics

Dual-Resonance U-Shaped Wearable Antenna with T-Slot Ground for On-Body Biomedical Devices

A. Abuelhaija — 2025-09-02

This study introduces a miniaturized and adaptable dual-band textile antenna, meticulously designed for implementation in wearable biomedical systems. It functions at 2.45 GHz and 5.8 GHz, covering the ISM (Industrial, Scientific, and Medical) frequency ranges. The antenna features a U-shaped patch with a T-shaped slotted ground plane, built from denim fabric (εr = 1.68) and ShieldIt Super conductive material. Following several design optimizations—such as via placement, curvature conformity, and slot tuning—the final prototype shows reliable impedance matching (S11 < -10 dB across both bands) and consistent radiation performance, validated using CST and COMSOL simulations. The antenna maintains dependable performance on the human body, with SAR levels staying within safe exposure thresholds (1.18 W/kg at 2.45 GHz and 1.44 W/kg at 5.8 GHz). Although radiation efficiency drops are observed when worn (approximately -10.5 dB and -15.6 dB at 2.45 GHz and 5.8 GHz respectively) due to body absorption, the radiation pattern remains directed and functional. These characteristics make the design well-suited for body-worn communication systems used in healthcare monitoring, fitness tracking, and military contexts. This flexible antenna meets safety and comfort requirements, offering a viable solution for WLAN/WBAN implementations in wearable technology.

Flexible Multi-wideband Wearable Antenna for Preliminary Evaluation of Tumour Detection in Breast Phantom Model

Sheng Chong Chua — 2026-03-19

The growing demand for non-invasive and wearable breast cancer diagnostic tools has driven the development of flexible and wearable antennas for microwave imaging. This study presents a flexible multi-wideband wearable antenna designed for breast tumour detection, with targeted operation at the 2.4 GHz Industrial, Scientific, and Medical (ISM) band which fabricated on a breathable cotton substrate with a 0.035 mm copper layer, the antenna measures 83 × 60 × 1.52 mm³ and is backed by a 2×3 Artificial Magnetic Conductor (AMC) array to enhance the gain whilst suppressing back radiation. Simulations and measurements are conducted in free space and on a realistic three-layer breast phantom consisting of skin, fat and glandular which is properly characterise in terms of electrical parameter has successfully, demonstrate a directional radiation, strong resonance at 2.4 GHz and wideband performance above 5.04 GHz. The antenna exhibits insensitivity to bending angle up to 60° and exhibits a low Specific Absorption Rate (SAR) value of 0.23 W/kg (10 g), ensuring safety compliance for wearable use to human skin proximity. While the current design supports tumour detection with varying sizes between 2–10 mm, future work will focus on extending the bandwidth below 5 GHz and miniaturizing the structure for enhanced early-stage diagnosis.

Global Minimality in Constrained Inverse Source Problems for Metamaterials

M. R. Khodja — 2025-09-19

Global minimality, boundedness, and uniqueness are established for a general, physically motivated class of inverse source problems in non-homogeneous electromagnetic media with generalized constitutive parameters. The existence of a solution was addressed earlier. The radiating source, represented by the current density, was reconstructed earlier by minimizing its L²-norm constrained to produce a prescribed radiated field while ensuring vanishing reactive power. Using the L²-norm allows for an analytically tractable measure of the physical resources of the source, while the reactive power constraint maximizes transmitted power. Numerical study suggests that sources within active metamaterial substrates can have remarkable tuning behaviors. Tuning stability can be achieved along specific permittivity and permeability curves on zero-reactive power plots. Each permittivity or permeability value can correspond to a discrete set of dual parameter values that enable effective tuning. The tuning characteristics observed suggest that double-positive (DPS) and double-negative (DNG) substrates are more favorable for tuning than single-negative (SNG) materials, possibly due to interactions dominant in DPS and DNG media. These results fill an analytical gap in the solution of a problem that is both intriguing and challenging due to its general formulation, which requires minimizing an objective functional with nonconvex functional constraints on an unbounded domain. They also offer numerical insights that may have implications for the design and optimization of sources in complex media, which is a topic of significant current interest.

Ultra-Compacted Antenna-based Capsule Endoscope in the ISM Band

Marwah Hassooni — 2026-03-19

This article presents a proposal for the miniature implantable antenna of a microstrip patch that covers ISM bands (2400–2483.5 MHz) for deep-tissue implantation with a volume of just 0.3 mm³. The proposed antenna is the smallest and lightest antenna manufactured for wireless capsule endoscopy. The antenna can be integrated with an imaging sensor, electronic components, and a battery. The proposed Microstrip Patch Antenna MPA shows a 483 MHz wider bandwidth at 2483.5 MHz; Beef muscles were used to validate the antenna's performance experimentally. The safety issues are assessed to examine the performance of the proposed antenna incorporated in an endoscopy capsule device by considering the specific absorption rate (SAR).

A Truly S-shaped Slot-loaded Broadband Microstrip Antenna for 5G Communication

S. Goswami — 2025-08-31

In this paper, a compact, microstrip-fed, wideband patch antenna loaded with a novel truly S-Shaped slot structure is proposed for the 5G communication systems. Firstly, a basic rectangular patch antenna with modified ground plane is designed with resonating frequency 3.13 GHz and bandwidth of 830 MHz from 2.65 GHz to 3.5 GHz. Then, an S-shaped slot, resembling the actual shape of the alphabet ‘S’ is introduced at the middle of the patch to achieve wideband operation from 2.7 – 5.6 GHz covering a part of the sub-6 5G communication band. In order to compare the performance of the truly S-shaped slotted antenna with that of the conventional one, another antenna with the abrupt 90⁰ bending S-shaped slot is also designed and the performances of both the antennas are illustrated. With introduction of the slot, the resultant antenna resonates at two resonating frequencies 3.21 GHz and 5.45 GHz, corresponding to the operating modes TM₁₀ and TM_d0 of the patch and the slot, respectively. The proposed antenna offers wide operating bandwidth of 2.9 GHz with overall gain of ~2 dBi at both the resonating frequencies. A fabricated antenna prototype is used to validate the antenna performance with the simulated results.

Microwave Compact Biconical Antenna with Low Diffraction Lobes for UAV Control Systems with Protection from Jamming

Stepan Piltyay — 2026-03-19

Results of theoretical investigation, numerical simulation, constructive development and experimental measurements of new compact biconical antenna for UAVs are presented in this article. Peculiarity of designed antenna consists in low diffraction lobes in its radiation pattern. This feature was achieved by using dielectric disc in the center region of antenna’s structure between conducting cones. Operating frequencies of antenna in the microwave range ensure protection from electronic jamming systems with quasi-isotropic antennas. Due to high attenuation of radiated electromagnetic waves at microwave frequencies, only directed antennas can create effective jamming of UAV in this band. Such possibility of adverse impact on UAV control system is excluded by low diffraction lobes of applied antenna and a priori unknown operation frequency of wireless control system. Measured results showed that at operating frequency designed antenna with coaxial-to-waveguide transition has VSWR equal to 1.6, maximal value of gain is 6.3 dBi. Measured diffraction lobes of radiation pattern in range of elevation angle −30–+30° from the antenna’s axis are less than −20 dBi. Designed compact biconical antennas were successfully used in new UAV control systems for military applications.

Design and Modeling of a Photonic Crystal Multiplexer Using Artificial Intelligence

P. Karami — 2025-04-16

In this paper, design and modeling of an all-optical 2×1 multiplexer based on 2D photonic crystals and artificial neural networks (ANNs) are presented. The proposed structure aims to maximize the difference between the output powers in logical states, which is critical for enhancing the system ability to distinguish between these states. In this study, an ANN model is employed to accurately predict the normalized output power of the designed photonic crystal multiplexer, providing a time-efficient alternative to conventional simulation methods for analyzing multiplexer behavior across various logical states. The results demonstrate significant improvements in signal separation and overall performance compared to previous works. Additionally, a detailed comparison of the normalized output power for different logic states is provided, highlighting the advantages of the proposed design.

A Miniature Hexa-Band Antenna for Internet of Things Applications Using Six Quarter-wavelength Resonators

Y. M. Hasan — 2025-04-16

This work presents a compact, low-cost hexa-band microstrip antenna for Internet of Things (IoT) applications. The proposed hexa-band antenna is composed of simple six-λ/4 resonators to generate six resonant frequencies: GSM 1.84 GHz (1.8 –1.89 GHz), Bluetooth 2.31 GHz (2.25 –2.375 GHz), WiMAX 3.3 GHz (3.16 –3.47 GHz), WiFi 4.63 GHz (4.34 –5 GHz), upper WLAN 6.1 GHz (5.8 –6.91 GHz), and X-band 9.26 GHz (8.87 –9.83 GHz). The proposed hexa-band antenna is fabricated using FR4 substrate with (23 × 20 × 1.6) mm3 dimensions, and its measured results are presented to validate the simulated results. Results from simulations and measurements are used to examine the radiation properties, including radiation patterns, gain, efficiency, VSWR, and reflection coefficient. The proposed hexa-band antenna has a miniaturized size and good radiation performance.

A Super-Wideband Miniaturized Graphene-Based Folded Monopole Antenna

L. Guo — 2025-02-15

A graphene-based folded monopole antenna with super-wideband bandwidth and a small volume is proposed in this paper. The antenna features a disc-loaded folded cylindrical configuration that mainly consists of graphene-powder and graphene-ink cylinders, along with copper discs. Two primary radiation modes are generated and combined to achieve the desired super-wideband bandwidth. The applied graphene-powder and graphene-ink cylinders serve as crucial radiating and tunable elements, rendering the antenna impedance matched across the super-wideband range. Furthermore, direct current (DC) excitation combined with conducting wires is utilized to improve impedance matching and enhance the operating bandwidth toward lower frequencies. The measured results indicate that the antenna has a super-wideband operating bandwidth across 0.114-0.202 GHz and 0.34-18 GHz (|S11| <-6 dB). The measured antenna peak gains range from -3.75-3.50 dBi. The antenna dimensions can be maintained at 0.006λL ×0.006λL × 0.011λL, where λL is the wavelength in free space at the lowest operating frequency.

Polarization-independent wideband meta-material rasorber with wide transmission window based on resistor loaded circular and split ring resonators

A. Kumar — 2025-02-20

A dual polarized with high absorption to right side and wide in-band transmission is proposed in this study. Our proposed design consists of four modified split ring resonators on the top layer and four lumped resistor of 150 Ω value is connected between them to absorb the incoming EM wave in the out-ofband frequency regime.The circular slotted cut on the lower layer is responsible for in-band transmission. The lower layer is behaving as a ground plane for out-of-band absorption and and passing a range of frequency for the transmission band. So, bottom layer is behave as a band-pass frequency selective surface filter. The design has an overall thickness of 0.18λ and a fractional bandwidth of approximately 113%. The entire design exhibits an insertion loss of 1.10 dB at the transmission band at around 5.93 GHz and exceeding 80% absorption from 2.8 GHz to 10.0 GHz. The proposed design is polarization insensitive due to its symmetrical design and angularly stable up to 45Åã for both both TE and TM polarization of wave. The novelty of the proposed design lies in its wide out-of-band absorption, wide in-band transmission, minimal thickness, high fractional bandwidth, good angular stability, cost-effectiveness, accessibility through the use of inexpensive materials for manufacture and simple design. To analyze the proposed rasorber, we have investigated the polarization behavior, surface current distribution and design other parameters. Lastly, the proposed structure has been constructed using PCB technology and validated in a semi-anechoic chamber. The simulated and measured responses exhibit a high degree of agreement.