PIER M | PIER Journals

2025-12-19

PIER M

Vol. 136, 86-94, 2025

download: 20

Dual-Mode BaTiO3 Ceramic Filter with Gold-Copper Metallization

Víctor Daniel Vazquez Pereira, Marcelo E. Chávez, Sebastián Murcia, Jordi Verdú Tirado and Pedro de Paco

In the design and fabrication of ceramic filters, the quality of metallization is crucial to minimize resistive losses and ensure optimal resonator performance. This work presents the design and fabrication of a monoblock dual-mode filter with two distinct types of couplings, based on barium titanate (BaTiO₃) ceramics, operating at S-band frequencies. Sputtering deposition was used to create a 5 nm gold seed layer, on which a 30 μm copper metallization was grown through electroplating. This method guarantees high conductivity in the resonator coating, and test results demonstrated that the fabricated device offers very good filtering performance with a minimal insertion loss of 0.57 dB.

Dual-Mode BaTiO3 Ceramic Filter with Gold-Copper Metallization

2025-12-19

PIER M

Vol. 136, 77-85, 2025

doi:10.2528/PIERM25110902

download: 12

Design of Near-Field Focusing Optical Transparent Metasurface for Millimeter-Wave Communication

Licong Fan, Yuan Yao, Jingchang Nan and Yifei Wang

Low-emissivity glass, commonly employed in building curtain walls strongly reflects and weakly transmits millimeter-wave signals, thereby hindering signal propagation. To address this issue, this paper introduces a novel method that leverages the low-emissivity film itself to design a metasurface for enhanced signal transmission. Two specific metasurface designs are presented. The simulation results validate the proposed method. For the design targeting linearly polarized waves, a 23 dB enhancement in the transmitted electric field is achieved compared to that of uncoated glass. The design for circularly polarized waves achieves a 22 dB enhancement. Both metasurfaces exhibit excellent wide-angle performance, maintaining single-point focusing up to a 30° incidence angle with an electric field enhancement exceeding 15 dB. The proposed millimeter-wave transparent metasurface features a simple structure, supports wide-angle incidence, and can be deployed over large areas with adjustable focal points to meet communication requirements. This work provides a reliable solution for mitigating millimeter-wave transmission loss through low-emissivity glass.

Design of Near-Field Focusing Optical Transparent Metasurface for Millimeter-Wave Communication

2025-12-19

PIER M

Vol. 136, 68-76, 2025

doi:10.2528/PIERM25091105

download: 15

Machine Learning-Based RCS Prediction for Metasurface-Integrated Cavity Structures

Xi Liu, Peng Nian, Yu Zhang, Yi Ren, Yi-Xin Guo, Yang-Chun Gao and Bing Chen

Conventional full-wave methods face prohibitive computational costs for far-field scattering optimization of metasurface-integrated cavity structures. To address this limitation, a lightweight residual neural network is introduced within a two-stage scattering prediction framework. This framework effectively mitigates model degradation. The first stage employs shallow convolutional networks to extract local phase-coupling features. The second stage integrates residual layers with fully connected layers to refine cross-scale scattering responses. A compact CNN-ResNet surrogate model is developed for rapid cavity scattering prediction. With only 2.5×10⁴ parameters and training on 500 full-wave samples spanning 6.0-16.0 GHz, the model achieves high computational efficiency. The proposed approach directly maps binary phase-coded matrices to far-field electromagnetic characteristics. Extensive validation on a cavity structure across 6.0-16.0 GHz demonstrates excellent accuracy. The per-sample runtime is reduced from hours to milliseconds while maintaining prediction errors below 3 dB. These results confirm the effectiveness of the approach in enabling fast and accurate electromagnetic scattering prediction for complex cavity environments. The approach provides a practical solution for metasurface-integrated cavity optimization.

Machine Learning-Based RCS Prediction for Metasurface-Integrated Cavity Structures

2025-12-17

PIER M

Vol. 136, 57-67, 2025

doi:10.2528/PIERM25101001

download: 36

High Gain and Bandwidth Enhanced Microstrip Patch Antenna with Defective Ground Structure Loaded with Metamaterial Unit Cells for Intelligent Transportation Systems

Sunil K. Dubey, Ashok Kumar Shankhwar, Nand Kishore and Alkesh Agrawal

In the manuscript a novel design of microstrip patch antenna with moderate degree of complexity is proposed in terms of metamaterial based unit cells as radiating patch on the top as well as metamaterial based periodic structure as defected ground structure at the bottom (MRPMGS) for Intelligent Transportation System (ITS) applications. The novel design of patch antenna exhibited multibands with broad-band transmission patterns, improved high gain and compact structure. The MRPMGS has a three layered structure with overall dimensions of 32 mm × 28 mm × 1.6 mm. The top layer with radiating patch has unit cell(s) with dimensions of 3.6 mm × 3.6 mm, and at the bottom the defective ground structure (DGS) has unit cell(s) with dimensions of 4 mm × 4 mm. The middle layer is of FR4 substrate with 1.6 mm thickness. The MRPMGS has experimental (simulated) transmission frequencies at 11.54 GHz (11.24 GHz), 12.91 GHz (12. 98 GHz), and 13.20 GHz (13.48 GHz) with reflection coefficients of -20.91 dB (-25.16 dB), -26.19 dB (-29.36 dB), and -18.94 dB (-26.02 dB) respectively. The VSWR varies between 1 and 3. The radiation efficiency reaches 80%, and high gain varying between 2.35 and 5.5 is achieved at the desired frequencies.

High Gain and Bandwidth Enhanced Microstrip Patch Antenna with Defective Ground Structure Loaded with Metamaterial Unit Cells for Intelligent Transportation Systems

2025-12-16

PIER M

Vol. 136, 46-56, 2025

doi:10.2528/PIERM25090302

download: 45

Auto-Calibration of Near-Field Microwave Measurements for Complex Permittivity Estimation

Andrei Ludvig-Osipov, Simon Stenmark, Thomas Rylander and Tomas McKelvey

This paper presents a numerical study of a novel method for auto-calibration of scatteringparameter measurements in a near-field microwave sensor system. The here proposed method is applied to estimation of the average complex permittivity in a measurement domain from the scattering parameters, corrupted by gain uncertainties in the measurement instruments. Simultaneously with the average complex permittivity, the gain uncertainties are also estimated. The characteristic property of the proposed method is that no simplified mathematical model of the measurement domain is assumed, and instead a set of a-priori calibrated measurements is used. Numerical studies demonstrate the performance of the method in noiseless and noisy settings with and without nuisance stochastic perturbations in the measurement domain. An approach to compensate for the stochastic perturbations in the measurement domain permittivity is proposed, and it demonstrates an improved performance of the method in numerical examinations.

Auto-calibration of Near-field Microwave Measurements for Complex Permittivity Estimation

2025-11-17

PIER M

Vol. 136, 33-45, 2025

doi:10.2528/PIERM25082502

download: 133

Enhanced Low-Resolution Contrast Operator Using Neural Networks for E-Polarized EM Scattering Problems

Daan van den Hof, Martijn Constant van Beurden and Roeland J. Dilz

Coarse discretization introduces significant errors in the solution of scattering problems, in part due to discretization errors in the contrast operator. We present a procedure for the automatic construction of a modified contrast operator for electromagnetic scattering problems by using trainable neural networks to represent a modified contrast operator. We achieve a higher accuracy on a coarse discretization while still keeping computation time down compared to a fine discretization. By using synthetic data from a full-wave Maxwell solver to train the network for one-dimensional slab scatterers and two-dimensional polygonal scatterers, we are able to use the techniques found in deep learning to improve accuracy in coarse-grid forward scattering problems.

Enhanced Low-resolution Contrast Operator Using Neural Networks for E-polarized EM Scattering Problems

2025-11-11

PIER M

Vol. 136, 22-32, 2025

doi:10.2528/PIERM25031101

download: 95

Parameter Enhancement of Vivaldi Slot 1×2 Array MIMO Antenna Using AMC

Ameet Mukund Mehta, Shankar B. Deosarkar, Anil Bapusa Nandgaonkar and Avinash R. Vaidya

A wide band, high gain 1 × 2 array Vivaldi shaped slot Substrate Integrated Waveguide (SIW) Multiple Input Multiple Output (MIMO) antenna with square shaped periodic Artificial Magnetic Conductor (AMC) placed beneath the antenna for applications in X band is presented. A two-port MIMO antenna backed by AMC patches is designed and realized for enhanced gain and bandwidth. The single antenna 1 × 2 array has electrical dimensions of 1.57λ_r × 1.13λ_r × 0.027λ_r. The designed antenna structure has bandwidth of 1.39 GHz (8.79 GHz-10.18 GHz) with a percentage bandwidth of 14.65% and Gain of 11.67 dBi. The edge to edge distance between the MIMO antenna elements is 5 mm (λ_r/4). The periodic AMC patches improve vital MIMO antenna performance metrics like Isolation, Envelope Correlation Coefficient (ECC), Diversity Gain (DG), Channel Capacity Loss (CCL) and radiation pattern. The unit cell analysis of periodic square AMC patch and a polynomial regression model to find the best goodness of fit for Gain-Bandwidth product versus square AMC patch size is studied. Antenna gain variation seen over the complete bandwidth is < 1 dBi which makes it a flat gain response antenna. The proposed high-gain, wide-band 1 × 2 Vivaldi-slot SIW MIMO antenna with AMC is suitable for X-band radar, point-to-point high-throughput wireless links, and compact platform communication systems requiring robust diversity performance.

Parameter Enhancement of Vivaldi Slot 1×2 Array MIMO Antenna Using AMC

2025-11-03

PIER M

Vol. 136, 13-21, 2025

doi:10.2528/PIERM25071106

download: 115

Selective Signal Transmission and Crosstalk Suppression Based on Double-Layer RFID Tags

Peiying Lin, Jiangtao Huangfu, Xixi Wang, Dana Oprisan and Yanbin Yang

This paper presents a passive, structure-based approach for selective signal transmission and crosstalk suppression in dense radio frequency identification (RFID) tag environments. The proposed method employs a mechanically reconfigurable double-layer tag design based on the mirror-antenna principle, which enables dynamic switching between transmission and shielding modes by adjusting the interlayer spacing. Simulation results demonstrate pronounced differences in the reflection characteristics and radiation intensity of the tag under the two operating modes at 915 MHz. Experimental validation further confirms the effectiveness of the system in mitigating interference and ensuring reliable tag identification in multi-tag scenarios. The design is compact, energy-efficient, and cost-effective, supporting scalable applications in smart retail and automated inventory management.

Selective Signal Transmission and Crosstalk Suppression Based on Double-layer RFID Tags

2025-10-30

PIER M

Vol. 136, 1-12, 2025

doi:10.2528/PIERM25071303

download: 204

Coin-Sized Dual-Band Millimeter-Wave (mmWave) Antenna with Machine-Learning-Guided Impedance Prediction

Ahmed Jamal Abdullah Al-Gburi

This study suggests a coin-sized (10 × 8 × 0.64 mm³) millimetre-wave antenna that simultaneously resonates at 28 GHz and 38 GHz and is supported by a machine-learning surrogate for near-instant impedance evaluation. Realised on Rogers 6010 LM laminate (ε_r = 10.2), the radiator maintains |S₁₁| ≤ -10 dB across 26.5-29.9 GHz and 37.2-39.7 GHz while providing peak gains of 3.8 dBi and 4.1 dBi in the lower and upper bands, respectively. A design-of-experiments sweep, comprising 330 full-wave simulations, generated the training corpus for a random-forest regression model. The surrogate predicts frequency-resolved |S₁₁| with a mean-absolute error below 0.7 dB and coefficients of determination of 0.93 at 28 GHz and 0.84 at 38 GHz. The evaluation time is reduced from approximately 155 s per full-wave electromagnetic simulation to 0.1 s per surrogate query, enabling real-time design exploration. Eight-fold cross-validation confirms model stability, while feature-importance analysis identifies the geometric parameters most influential to dual-band matching. The learning-guided workflow therefore offers a fast and reliable alternative to exhaustive simulation, accelerating the optimisation of compact mmWave antennas for instrumentation, sensing, and future front-end modules.