Metamaterials are artificially engineered structures that exhibit electromagnetic properties not normally found in natural materials, such as negative permittivity and permeability. These unique characteristics make metamaterials highly useful for electromagnetic wave absorption applications. In this paper, a compact six-band metamaterial absorber operating in the microwave frequency range is proposed and analyzed. The designed absorber consists of a symmetric metallic patch structure printed on a lossy FR-4 dielectric substrate, backed by a copper ground plane to eliminate transmission. The proposed unit cell supports six distinct resonance frequencies at 2.76 GHz, 6.25 GHz, 11.54 GHz, 13.28 GHz, 15.73 GHz, and 17.38 GHz, achieving absorption levels greater than 92% at all bands, with peak absorption exceeding 99%. Due to the symmetric geometry, the absorber exhibits polarization-independent behavior under normal incidence. Additionally, the structure demonstrates angular stability for incident angles up to 45° over a wide frequency range. The absorption mechanism is explained using normalized impedance matching, surface current distribution, and electric field analysis. The simulation results confirm that near-unity absorption occurs when the effective impedance of the metamaterial matches the free-space impedance. The entire design and performance evaluation are carried out using CST Microwave Studio 2018. Owing to its compact size, multi-band operation, polarization insensitivity, and high absorption efficiency, the proposed metamaterial absorber is suitable for applications such as electromagnetic interference shielding, radar cross-section reduction, sensors, and microwave communication systems.

The article presents a miniaturized ultra-wideband (UWB) antenna tailored for modern defense and small satellite communication requirements. Designed and optimized using CST Microwave Studio, the antenna delivers superior electromagnetic performance across both Sub-6GHz and millimeter-wave frequency ranges. Realized on an FR4 substrate with overall dimensions of 10 × 12 × 1.5mm³, the prototype achieves an impressive operating bandwidth of 3.4-14GHz, equivalent to an impedance bandwidth of 121.8%. The measured results highlight a peak gain of 4.56 dBi, a return loss of -28 dB, and a radiation efficiency of 82.9%, ensuring reliable performance over a broad spectrum. With an electrical size of 0.113λ × 0.136λ × 0.017λ, the proposed design demonstrates remarkable compactness while maintaining stable radiation patterns and high efficiency. These characteristics make the antenna a strong candidate for resilient, interference-resistant, and high-performance applications in defense systems and CubeSat missions.

ABSTRACT Ceramic‐based Microstrip patch antennas (MPA) are widely used in wireless communication systems to address emerging telecommunications challenges related to size, bandwidth, and transceiver system gain. This study demonstrates the use of Barium titanate ceramic substrates for microstrip patch antennas with frequencies ranging from 8.2 to 12.4 GHz (X‐band). The dielectric ceramic‐based substrate, with a thickness of 1.23 mm, a length of 34 mm, and a width of 17 mm, was used to simulate the microstrip patch antenna. The research focused on electromagnetic parameters such as permittivity, permeability, dielectric loss, and magnetic loss. The nanocrystalline BaTiO 3 was synthesized by high‐energy planetary ball milling followed by calcination at a temperature of 1200°C and sintering 1300 °C . The XRD graph shows a single tetragonal perovskite structure with an average crystallite size of 95.63 nm. The FESEM micrograph revealed a grain size of 2.73 µm. The microstrip patch antenna operating in X‐band, based on the BT ceramic, has an excellent simulation return loss of ‐44.48 dB (9.91 GHz) and measured return loss ‐34.94 dB (9.95 GHz), simulation bandwidth 361.19 MHz, and measured bandwidth 366.8 GHz, directivity of 7.13 dB, gain of 6.26 dB, and VSWR <2 using CST Microwave Studio v. 2019. The microstrip patch antenna with wideband and high‐gain is suitable microwave dielectric material for 5G network technologies.

Background. Improving the multipactor resilience of high-power microwave devices used in satellite communication systems presents a primary objective for designers of space technology. Aim. This study investigates a method to enhance the multipactor threshold in high-power cavity-based low-pass filters for operation in deep space vacuum with associated radiation factors by optimizing the edge geometry of capacitive sections. Methods. The proposed approach passively suppresses discharge by tailoring the electric field distribution in critical gaps and can be achieved without additive coatings that alter the electrophysical properties of materials, a method commonly employed for this purpose. The research methodology combined electromagnetic field simulation in CST Microwave Studio with thermal analysis in CST MPhysics Studio and resulting field maps using for multipactor stability analysis in SPARK3D, employing an electron tracking algorithm. Results. A key finding is the non-monotonic dependence of the multipactor threshold power on the edge fillet radius. An optimal concave radius of R = 2 mm was identified, increasing the threshold power by approximately 40 % (relative to R = 0,1 mm). Conversely, using a chamfer or a convex rounding degraded performance severely, reducing the threshold power by roughly an order of magnitude. Conclusion. The results are obtained demonstrates the viability of passive geometric techniques as a robust and reliable strategy for multipactor suppression in the design of high-reliability space-borne microwave components.

Background. According to a number of researchers, fractal antennas, including those for the gigahertz frequency range, have a fundamental multi-frequency, which makes it possible to reduce their number in a compact device for wireless communication designed for various operating bands. At the same time, there are publications in which such an advantage of fractal antennas in comparison with their canonical counterparts is denied. It is important to note that a fractal is different from a fractal. There are fractals obtained by scale-invariant fragmentation of some initial object («Sierpinski gasket», «Koch curve», «Cantor set», etc.). But there are also fractals obtained by scale-invariant branching of the original object («fractal tree», «Julia set», «Newton basins», etc.). There is reason to believe that antennas created on the basis of fractals of fragmentation and branching will have different properties. Aim. Investigation of the characteristics of a fractal patch antenna of the «fractal tree» type, designed for the gigahertz frequency range, in its various iterative approximations. Methods. This goal is achieved by using electrodynamic modeling in the CST Microwave Studio software package by comparing the characteristics of a gigahertz patch antenna obtained for the first three iterations of the fractal tree as a prototype of a fractal antenna. Results. Quasi-fractal patch antennas (the first three iterations) of the «fractal tree» type in the form of an ideally conductive patch on a dielectric substrate with a relative permittivity of 3,55 mm and a thickness of 0,203 mm, on the opposite side of which there is a grounded metal shield, are studied. The frequency dependences of the element S11 of the scattering matrix, the standing wave coefficient of the voltage and the input impedance are constructed. The radiation patterns of the studied antennas in polar and spherical coordinates at the observed operating frequencies are also presented. Conclusion. Step-by-step simulation of a «fractal tree» type patch antenna in the frequency range 0-50 GHz has shown that as the branched type fractal evolves, the number of antenna operating bands can be increased.

Background. Miniature quadrupole gigahertz receiving and transmitting antennas with circular radiation polarization are of interest for high-speed stable 5G wireless communication systems, including those with unmanned aerial vehicles. In addition, such antennas must be multi-band with the ability to quickly switch from one operating frequency to another. The problem can be solved by using quadrupole patch antennas, including those with a two-way patch. Recently, publications have also begun to appear advertising fractal antennas that combine fundamental multiband with compactness due to scale invariance. However, there are works in which the advertised advantages of fractal antennas are denied. Aim. Investigation of the real effect of fractalization on the characteristics of a printed quadrupole antenna for the gigahertz frequency range. Methods. This goal is achieved by using electrodynamic modeling in the CST Microwave Studio software package by comparing the obtained characteristics of the initial canonical antenna and its three fractal iterations. Results. A two-sided patch antenna made of a bilaterally foiled dielectric with a relative permittivity of 3.55 mm and a thickness of 0.203 mm, consisting of two quarter-wave dipole antennas connected in parallel, is investigated. For the initial non-fractal antenna and its three fractal iterations according to the “Sierpinski square carpet” type, frequency dependences of the element S11 of the scattering matrix, the standing wave coefficient of the voltage and the input impedance are constructed. The radiation patterns of the studied antennas in polar and spherical coordinates at the observed operating frequencies are also presented. Conclusion. By step-by-step simulation of the number of iterations of the fractal structure of the above type of the printed quadrupole antenna in the frequency range up to 100 GHz, it is shown that its fractalization does not introduce significant changes in the characteristics, but only leads to a complication of the design and an increase in the cost of the antenna.

This study presents a compact bulb-shaped ultra-wideband microstrip patch antenna designed for microwave imaging applications, more specifically, breast tumor detection. Traditional antenna design methods for medical applications are time-consuming. The proposed antenna, designed in CST Microwave Studio 2019 on a Rogers RT 5880 substrate with a slotted ground plane, achieves a bandwidth of 11.1 GHz, a gain of 6.2 dBi, and an efficiency above 80%. In response to the limitations of conventional antenna design approaches, this study introduces a novel machine learning-based approach to accelerate the design process, where a custom CatBoost model predicts key dimensions—feedline width, large circle radius, and small circle radius, based on the performance metrics such as resonant frequency, minimum reflection coefficient, bandwidth, real and imaginary part of impedance. The model achieves a cross-validation score of 95.13% with a mean absolute error of 0.0166 mm, outperforming conventional machine learning approaches. Shapley Additive exPlanations analysis is applied to interpret feature contributions. A prototype is fabricated using the prediction of a machine learning model. The bulb-shaped antenna structure, wide operational bandwidth, consistent gain, and strong sensitivity to tissue dielectric variations enhance its effectiveness for breast tumor detection compared with conventional antennas. Furthermore, experiments with a breast phantom confirmed the prototype’s suitability for detecting dielectric contrasts in tissue, establishing a foundation for machine learning-assisted antenna design in medical imaging.

This study introduces a dual-band circular split-ring resonator (CSRR)-based metamaterial absorber (MTMA) designed for high-sensitivity sensing of both solid and liquid materials. The proposed structure, fabricated on a Rogers RT 5880 substrate with copper layers, achieves near-perfect absorption rates of 99.99% at 10.48 GHz (X-band) and 99.97% at 14.57 GHz (Ku-band), optimized through CST Microwave Studio simulations. The MTMA’s triple-stage design refinement enhances resonance characteristics, enabling precise detection of dielectric variations in substrates and liquids via measurable frequency shifts. Experimental validation confirms robust performance, with sensitivity of up to 2.51 GHz/εᵣ and quality factors reaching 189, thus outperforming existing single-band metamaterial sensors. The absorber’s compact size and consistent response under varying permittivity’s make it suitable for applications in biomedical diagnostics, fuel adulteration detection, and industrial quality control. By bridging gaps between simulation and real-world implementation, this work advances metamaterial-based sensing technology, offering a scalable and efficient solution for electromagnetic wave manipulation in next-generation sensor systems.

This article presents the design and analysis of the reconfigurable reflectarray structure based on metamaterials for Sub-6 GHz 5G applications. The proposed reflectarray structure is printed on a 1 mm-thick FR4 dielectric substrate with a total size of 180 × 180 mm2. The reflectarray consists of 144 unit cells, each with dimensions of 15 × 15 × 1 mm3. The unit cell design is a single layer based on multi-concentric square rings. A single layer is used to achieve a negative constitutive parameter (-εr or -μr); multiple rings of different sizes provide a wide reflection bandwidth to improve the performance of the reflective surface. Dual bands of reflection were observed. The first band of reflection is 2.6 GHz, 1.98-4.6 GHz, and the second band is 1.71 GHz, 7.41-9.1 GHz. Two PIN diodes are used in each unit cell of the reflectarray structure for reconfigurable behavior achievement. Depending on the diode states, the phase distribution across the proposed reflectarray structure changes, and the incident waves are reflected at different angles. This work conducted a comprehensive analysis of S-parameters, constitutive parameters, and refractive index, based on full-wave analysis. The CST Microwave Studio software package was used to design and analyze the proposed design structures. A good agreement was observed between the measurement results and those from the simulation.

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.

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.

Unmanned Aerial Vehicles (UAVs) are integral components of future 6G networks, offering rapid deployment, enhanced line-of-sight communication, and flexible coverage extension. However, UAV communications in low-altitude environments face significant challenges, including rapid link variations due to attitude instability, severe signal blockage by urban obstacles, and critical sensitivity to transmitter–receiver alignment. While traditional planar reconfigurable intelligent surfaces (RIS) show promise for mitigating these issues, they exhibit inherent limitations such as angular sensitivity and beam squint in wideband scenarios, compromising reliability in dynamic UAV scenarios. To address these shortcomings, this paper proposes and evaluates a spherical-cap reflective intelligent surface (ScRIS) specifically designed for dynamic low-altitude communications. The intrinsic curvature of the ScRIS enables omnidirectional reflection capabilities, significantly reducing sensitivity to UAV attitude variations. A rigorous analytical model founded on Generalized Sheet Transition Conditions (GSTCs) is developed to characterize the electromagnetic scattering of the curved metasurface. Three distinct 1-bit RIS unit cell coding arrangements, namely alternate, chessboard, and random, are investigated via numerical simulations utilizing CST Microwave Studio and experimental validation within a mechanically stirred reverberation chamber. Our results demonstrate that all tested ScRIS coding patterns markedly enhance electromagnetic field uniformity within the chamber and reduce the lowest usable frequency (LUF) by approximately 20% compared to a conventional metallic spherical reflector. Notably, the random coding pattern maximizes phase entropy, achieves the most uniform scattering characteristics and substantially reduces spatial field autocorrelation. Furthermore, the combined curvature and coding functionality of the ScRIS facilitates simultaneous directional focusing and diffuse scattering, thereby improving multipath diversity and spatial coverage uniformity. This effectively mitigates communication blind spots commonly encountered in UAV applications, providing a resilient link environment despite UAV orientation changes. To validate these findings in a practical context, we conduct link-level simulations based on a reproducible system model at 3.5 GHz, utilizing electromagnetic scale invariance to bridge the fundamental scattering properties observed in the RC to the application band. The results confirm that the ScRIS architecture can enhance link throughput by nearly five-fold at a 10 km range compared to a baseline scenario without RIS. We also propose a practical deployment strategy for urban blind-spot compensation, discuss hybrid planar-curved architectures, and conduct an in-depth analysis of a DRL-based adaptive control framework with explicit convergence and complexity analysis. Our findings validate the significant potential of ScRIS as a passive, energy-efficient solution for enhancing communication stability and coverage in multi-band 6G networks.

The design and analysis of a small hexagonal ring microstrip antenna optimized at 5.5 GHz are presented in this work. The FR4 substrate, which has a dielectric constant of 4.3 and a thickness of 1.6 mm, is used to fabricate the antenna because it is inexpensive and compatible with printed circuit board technology. By extending the effective current path and allowing for multiple resonant modes, the hexagonal ring geometry improves radiation performance and impedance bandwidth when compared to traditional rectangular patches. Using CST Microwave Studio, Characteristic Mode Analysis (CMA) is used to analyze the antenna's modal behavior. According to the CMA results, higher-order modes aid in stability, but the dominant resonant mode around 5.5 GHz largely controls the radiation mechanism. With an impedance bandwidth of 126 MHz (5.392–5.518 GHz), the simulated response exhibits a resonance of –20 dB at 5.5 GHz. The antenna produces strong current distribution along the hexagonal edges, broadside radiation, and a steady gain of 6.11 dBi. The design is appropriate for WLAN and Wi-Fi 5 (IEEE 802.11ac) applications because of these features. The hexagonal ring structure is an efficient technique for increasing bandwidth and performance in wireless systems, as demonstrated by the combination of CMA and full-wave simulations.

Abstract Two-dimensional (2D) materials exhibit exceptional properties—ultrafast carrier dynamics, tunable bandgaps, and strong light–matter interactions—that make them highly promising for next-generation optoelectronics. Across our recent studies, plasmonic enhancement using metallic nanoparticles has been demonstrated as an effective strategy to overcome the intrinsic limitations of 2D materials. This work presents the optical absorption behaviour of mono and bimetallic Au-Ag nanoparticles (NPs) integrated with graphene as 2D materials combining experimental characterization and simulation CST Microwave Studio simulations. SEM and UV–Vis measurements reveal predominantly spherical nanoparticles with localized surface plasmon resonance (LSPR) features around 575 nm and 795 nm. Finite element method (FEM) simulations confirm red-shifted absorption peaks with increasing nanoparticle size, while inter-particle distance exerts negligible influence. These results demonstrate that bimetallic Au-Ag/graphene systems provide enhanced tunability of LSPR responses compared to monometallic structures, offering potential for sensing and optoelectronic in broad wavelength applications.

The modern defense systems heavily depend on stealth technology where it is necessary to reduce the Radar Cross-Section (RCS) of platforms in order to minimize the detection. Nonetheless, onboard antennas severely decrease stealth of a vehicle because they are natural electromagnetic scatterers. This paper addresses the problem by developing low-observable microstrip patch antennas that reduce RCS without highly affecting communication functions. We designed and analyzed three antenna models which had a frequency range of 2 to 12 GHz using CST Microwave Studio. Radar Absorbing Material (RAM) and a Frequency Selective Surface (FSS) were used to come up with a baseline design, and geometric adjustments were subsequently made to the design. The results indicate that the end hybrid antenna has a high RCS reduction of up to 80 with minimum value of -15 dBsm as it is compared to the baseline. It achieves simultaneously a wide functional bandwidth of 3.5-7.8 GHz and returns loss of less than -10 dB. Although the antenna suffered a slight decrease in radiation efficiency, the antenna was able to maintain constant gain and directivity. By demonstrating that a synergistic approach of geometric shaping combined with current materials effectively suppresses backscattering, this study provides a possible course toward the implementation of effective antennas on stealth platforms.

Abstract This study presents a high-gain, trident-shaped, band-notched, four-element ultrawideband (UWB) multiple-input multiple-output (MIMO) antenna system, optimized using machine learning (ML) techniques. The single-element UWB antenna operates over a frequency range of 3.5 to 11.2 GHz, achieving a peak gain of 3.5 dBi. A band-notch characteristic is implemented in the 4.7-5.9 GHz range to reject the WLAN band and mitigate interference. The design is then extended into a four-element MIMO configuration, enhancing the peak gain to 5.1 dBi and achieving an impedance bandwidth of 114%, covering the 3.0-11.0 GHz range. The initial inter-element isolation exceeds 17 dB, which is further improved to more than 20 dB by introducing a decoupling structure.To further improve the gain and radiation characteristics, a metasurface comprising a 6 × 6 unit cell array is placed 23 mm above the MIMO structure, resulting in a peak gain of 9.5 dBi at 8.5 GHz. The proposed MIMO antenna system exhibits satisfactory diversity performance, with envelope correlation coefficient (ECC), diversity gain (DG), mean effective gain (MEG), and channel capacity loss (CCL) all falling within their respective acceptable limits. Additionally, various ML models are employed to optimize the reflection coefficient (|S 11 |) and gain. The predicted results align well with the CST Microwave Studio simulations. Among the models, Gaussian Process Regression (GPR) for |S 11 | and Fine Tree for gain yield the lowest root mean square error (RMSE) of 0.0082 and 0.3863, respectively, along with excellent R 2 scores of 0.9999 and 0.9847, confirming their superior prediction accuracy and generalization capability.

Glucose, as the core substance of energy metabolism in living organisms, exhibits significant differences in bioavailability, metabolic pathways, and physiological functions between its d- and l-enantiomers. Specifically, d-glucose serves as a key substrate in the cellular tricarboxylic acid cycle, while the l-enantiomer cannot be metabolized due to the absence of glucokinase, making it a non-caloric, diabetic friendly sweetener. The stark contrast in their bioactivity and application scenarios highlights the critical importance of developing rapid, label-free, and highly sensitive enantiomer discrimination technology for precision medical diagnostics and functional food development. This study innovatively proposes and validates a terahertz metamaterial sensor based on an open-ring resonator for precise identification of glucose enantiomers. Operating under a TE (transverse-electric) mode, the sensor demonstrates dual-resonance responses at 0.409 and 0.652 THz. Through full-wave simulation optimization using CST Microwave Studio®, the device was fabricated via UV photolithography and characterized with a terahertz frequency-domain spectroscopy system. Simulation results predict a high refractive index sensitivity of up to 222.3 GHz/RIU, while experimental measurements demonstrate the sensor’s capability for specific discrimination between d-glucose and l-glucose at concentrations as low as 2 mmol/l. At 8 mmol/l glucose concentration, the transmission peak intensity increase for l-glucose was 1.96 times greater than that of d-glucose. This sensor provides an innovative tool for real-time blood glucose monitoring and personalized diabetes treatment, demonstrating the unique technical advantages of terahertz metamaterials in the field of biological chiral recognition.

This paper investigates the implications of the reduction of patch length in Rectangular Microstrip Patch Antenna (RMPA) design. In order to determine the implications of the patch length reduction, two (2) rectangular microstrip patch antennae which were designed, modelled and simulated using the same procedures, the same software, the same feeding method, the same materials and the same dimensions of all the antenna parameters, with the exception of the length of the patch, were analysed. One of the antennae was adopted while the other was a newly designed antenna whose patch length was reduced by about 2% when compared with the length of the adopted antenna. The two (2) antennae were designed at 3.5 GHz resonant frequency and simulated using CST Microwave Studio Suite 2019 for 5G applications. Transmission line method was used as the feeding method of the antennae. Based on the results, it was found that the reduction in dimension of the patch length significantly affects the performance of the RMPA negatively. This implies that increment of the dimension of the patch length to certain level, enhances the performance of the RMPA.

Abstract Photon–magnon hybrid systems present a promising platform for the development of next generation devices in quantum information processing and quantum sensing technologies. In this study, we investigate the control of photon–magnon coupling (PMC) strength through systematic variation of the saturation magnetization Ms in a planar hexagonal-ring resonator (HRR) integrated with a yttrium iron garnet (YIG) thin film configuration. Using full-wave numerical simulations in CST Microwave Studio, we demonstrate that tuning the Ms of the YIG film from 1750 Oe to 900 Oe enables systematic control over the coupling strength across the 127–51 MHz range at room temperature. To explain the observed PMC dynamics, we develop a semiclassical analytical model based on electromagnetic theory, that accurately reproduces the observed coupling behavior, revealing the key role of spin density in mediating the light–matter interaction. The model is further extended to include the effects of variable magnon damping across different Ms values, enabling broader frequency control. These findings establish Ms as a key tuning parameter for tailoring PMC, with direct implications for the design of tunable hybrid systems for reconfigurable quantum devices.

This study presents an ultra-wideband, polarization-insensitive circuit analog absorber composed of multilayer resistive frequency selective surface structures. The proposed absorber architecture is characterized by a periodic configuration of square shaped loops incorporating lumped resistors, which are placed on dielectric layers that are interspersed with an air spacer. The simulated results demonstrate a reflection coefficient of less than − 10 dB within the frequency range of 5.2–20.09 GHz, exhibiting a fractional bandwidth of 117.75% under normal incidence. This performance encompasses the C, X, Ku, and K bands. The absorber design theory has been inspected then simulated in full wave analysis software CST microwave studio. The influence of parametric variations, including resistor values and the height of the air spacer, has been investigated to validate the sensitivity of the design parameters on the absorption bandwidth.