The proliferation of massive antenna arrays and the consequent intensification of near-field effects with 6G necessitate addressing critical security challenges in near-field communication environments. This paper presents a novel artificial noise-aided spatial and directional modulation (SDMN-AN) framework, specifically tailored for secure near-field communications. The proposed system integrates legitimate receiver indices, modulation symbols, and artificial noise (AN) confined to the null space of legitimate channels, thereby enhancing both spectral efficiency and communication security. Two precoding strategies—maximum-ratio transmission (MRT) and zero-forcing (ZF)—are investigated, offering trade-offs between hardware complexity and detection overhead. Analytical derivations of bit error rate (BER) bounds, corroborated by simulation results, underscore the superiority of the SDMN-AN framework in mitigating eavesdropping threats while significantly improving spectral efficiency, positioning it as a compelling solution for next-generation secure wireless networks.

Targeted communication is made possible using beamforming. It is extensively employed in many disciplines involving electromagnetic waves, including arrayed ultrasonic, optical, and high-speed wireless communication. Conventional beam steering often requires the addition of separate active amplitude and phase control units after each radiating element. The high-power consumption and complexity of large-scale phased arrays can be overcome by reducing the number of active controllers, pushing beamforming into satellite communications and deep space exploration. To address this, we propose a phased array antenna design based on dimensionality-reduced cascaded angle offset phased array (DRCAO-PAA). By applying singular value decomposition (SVD) to compress the coefficient matrix of phase shifts, our method reduces the number of active controllers while maintaining beam-steering performance. Furthermore, the suggested DRCAO-PAA was sing the singular value deposition concept. For practical application the particle swarm optimization algorithm and deep neural network Transformer were adopted. Based on this theoretical framework, an experimental board was built to verify the theory. Finally, the 16/8/4 -array beam steering was demonstrated by using 4/3/2 active controllers, respectively.

A hybrid PSO-FPA metaheuristic algorithm for ultra-low sidelobe and high-directivity synthesis of concentric circular antenna arrays for advanced radar applications.

The pattern synthesis technique of antenna arrays has a wide range of applications in radar and communication systems, which is an important research direction in the field of smart antennas. In order to improve the optimization performance of pattern synthesis of linear antenna arrays, an optimization method based on the Modified RIME Optimization Algorithm (MRIME) is proposed. RIME is a new heuristic algorithm inspired by the condensation process of frost ice in nature, which has a unique update mechanism with strong convergence as well as randomization. In the present work, MRIME is used for optimal pattern synthesis of a linear antenna array (LAA). One part of the present study is to optimize the side lobe level by optimizing the antenna current amplitude while maintaining a uniform spacing; the other part is to optimize the antenna position while assuming a uniform excitation in the synthesis of a sparse LAA, where constraints are imposed on the spacing of the array elements and aperture length, and suppression of the side lobe level with the position of the zeros in the specified direction is also achieved. In this article, simulation experiments for uniform linear arrays as well as sparse linear arrays are presented in detail, and the results show that the MRIME optimization algorithm outperforms most of the existing evolutionary classes of optimization algorithms in optimizing the side lobe level. This illustrates the potential of utilizing the MRIME optimization algorithm for antenna arrays and various other electromagnetism-related challenges.

Thermal control mode of an active phased antenna array using modified Fourier series in the presence of rapidly changing thermal flows over time

A novel 2-D pattern reconfigurable array using beamforming networks and reconfigurable antenna array

Abstract With the widespread application of smart antennas in 5G communication and radar detection, adaptive beamforming technology based on deep learning has become a research focus for improving the anti-interference performance of antenna arrays due to its powerful nonlinear modeling capability. It can transform the beamforming problem into a neural network regression problem, enabling the model to rapidly output an approximately optimal beamforming weight vector without prior information. Aiming at the issues of poor adaptability to dynamic interference and high computational complexity of traditional algorithms, this paper proposes IRDSNet, a novel adaptive beamforming algorithm based on Inception-ResNet-dual-pool Squeeze-and-Excitation Network (DP-SENet), to optimize the performance of uniform circular array antennas. IRDSNet integrates the Inception structure, depthwise separable convolution, and Ghost convolution to construct a multi-scale feature extraction module, enhancing the model’s feature extraction capabilities while maintaining a low parameter count. By introducing an improved DP-SENet, the model’s ability to focus on key features is enhanced, while the incorporation of residual modules optimizes feature transmission efficiency. Simulation results demonstrate that the IRDSNet algorithm achieves a null depth exceeding −90 dB at various interference angles, with an output Signal-to-Interference-plus-Noise Ratio (SINR) consistently above 23 dB and a short inference time, demonstrating excellent interference suppression performance.

Abstract Millimeter wave (mmWave) communication systems use beamforming and large antenna arrays to achieve high data rates by directing signals through narrow beams, reducing interference and enhancing transmission efficiency. Efficient beamforming requires real‐time beam adjustments to adapt to user positions and environmental changes, but traditional methods relying on frequent measurements can lead to significant overhead in dynamic environments. AI/ML approaches leveraging sensor data and historical information can improve beam prediction and tracking efficiency. Building on this, we propose a multimodal beam tracking model for UAV communication, integrating image and GPS data to predict UAV movement and optimize beam tracking. The model employs ResNet‐SE blocks for feature extraction, CAformer blocks for multimodal data fusion, and LSTM for capturing sequential historical features. Experimental results show that the proposed model outperforms single‐modal methods, achieving a 24.4% improvement in Top‐1 beam accuracy.

ABSTRACT Photonic‐assisted terahertz (THz) wireless communication is a promising solution for future high‐capacity wireless networks. However, the low output power and severe propagation loss of THz waves limit transmission distance. To overcome these challenges and support dynamic multi‐user connectivity, we demonstrate an integrated photonics‐assisted THz beamformer enabling broadband, beam‐squint‐free beam steering in the D‐band, based on silicon four‐channel tunable optical true‐time delay lines (OTTDLs). Each OTTDL combines an 8‐bit switchable delay and a continuously tunable delay unit, achieving a total continuous delay range of 0–394.24 ps. By providing true time delays, the proposed beamformer maintains a consistent beam direction across a wide operating bandwidth, thereby fundamentally eliminating beam squint. Leveraging this chip and a 1 × 4 dielectric rod antenna array, we achieve beam steering with a total beam switching time of 120 ns and a maximum angle of ±20.19°. We demonstrate wireless transmission with a line rate of 100 Gb/s at two distinct angles. To the best of our knowledge, this is the first integrated THz beamforming system that realizes broadband, beam‐squint‐free operation using OTTDLs. This work represents a significant step toward scalable, low‐latency, and high‐speed THz wireless networks, offering a viable pathway for dynamic beam management in future 6G systems.

In this work, a dual key-shaped antenna for 28/38 GHz mmWave applications is designed, analyzed, and tested using the Theory of Characteristic Modes. The antenna is printed on a 0.254mm thick substrate and has a compact footprint of 10 × 12mm², making it suitable for modern space-limited 5G devices. It supports two operating bands centered at 28GHz and 38GHz, with measured fractional bandwidths of 12.5% and 21.05%, respectively. At the lower band, the first four characteristic modes dominate the radiation, while Modes 2, 3, 4, 6, and 10 mainly shape the higher-band performance. To further enhance gain and cover wider practical needs, the design is extended into a four-element linear array with an overall size of 19.75 × 26 × 0.254mm³. The array provides peak gains of 10.5 dBi at 28GHz and 11 dBi at 38GHz, while maintaining more than 75% efficiency across both operating bands. A prototype of the antenna and array was fabricated and tested using in-house measurement facilities, showing good agreement with the simulated results. The proposed antenna system meets the key performance requirements for 5G mmWave communication and offers a compact and efficient solution for future 28/38 GHz wireless devices.

Introduction . Compensation for the negative impact of failed elements of digital antenna arrays on the characteristics of the antenna pattern is a key problem in the creation and operation of such systems. A large number of methods have been proposed to date to solve this problem. These are based on the search for a new amplitude–phase distribution in antenna elements, which allows the beamwidth and the side lobe level to remain unchanged. In the proposed methods, a new antenna weighting vector is searched in the weight space for the extremum of a quality function that accounts for the change of the antenna pattern due to failed elements. The search is performed by one of the known optimization methods, such as conjugate gradient, projection, genetic algorithms, etc. These methods implement some iterative search procedures, which significantly increases the time required to find the necessary solution and the load on the signal processor. Aim . To develop a direct algorithm for restoring the antenna pattern of a digital antenna array in presence of failed elements. Materials and methods . The developed recovery algorithm is based on the estimation of the spatial frequency of the received wave using signals in antenna elements by the least squares method. Results . A simple, non-iterative algorithm for timely restoring the antenna pattern of a digital antenna array is proposed. The conducted computer simulation showed that for the signal-to-noise ratio of 20 dB in the antenna elements, the algorithm restores the directivity, antenna beamwidth, and the first side lobe level with an accuracy of no worse than 2, 5, and 1 %, respectively, of the values of these parameters in the absence of failed elements Conclusion . The proposed algorithm for restoring the antenna pattern of a digital antenna array can be used in software of a signal processor controlling the operation of an antenna system to compensate for the influence of failed elements.

Due to the diversification of media functions of mobile phones, users can make calls and access the internet simultaneously, which has significantly increased the usage time of mobile phones. The exposure dose of the users in the combined electromagnetic fields (EMF) should be further quantified to better evaluate the public exposure safety. Different from most conventional EMF safety studies that only focus on a single frequency, this work not only discusses the mobile phone simultaneously operated in fourth-generation (4G) and fifth-generation (5G) mobile communications radiation impact on users, but also verifies that the miniaturized mobile phone multiple-input multiple-output (MIMO) antenna array can significantly reduce the specific absorption rate (SAR) absorbed by users. In this article, a miniaturized mobile phone MIMO antenna array is employed as the radiation source, and multi-pose human models are established to simulate the practical utilization of a smartphone. A systematic analysis of the SAR absorbed by the human model is conducted in both single and combined EMF scenarios. The results indicate that the peak SAR in various tissues under multi-frequency exposure is 1.02 to 15.85 times higher than that under single-frequency exposure.

To augment the feeble Raman scattering signal using a surface-enhanced Raman scattering (SERS) substrate, the directivity and reflection of the generated signal are critical factors. The heating impact of nano-SERS on silicon wafers, induced by strong laser power excitation, frequently leads to an elevation in the Raman spectrum profile, rendering certain changes with minimal intensity undetected. We proposed and demonstrated that the microscale resonator array of the dipole antenna architecture on Si-aerogel considerably amplified the Raman shift intensity of furfural. The microscale SERS chip consists of three material layers: a resonator antenna array layer (quartet-split silver rings), a dielectric material layer (Si-aerogel), and a ground layer (thin silver coating). The optimal dimensions of the quartet-split silver rings were determined through electromagnetic field simulation to ensure that excitation of the microscale SERS chip by a 785 nm (381 THz) laser induces localized surface plasmon resonance (LSPR) at the interface between the resonator antenna array layer and the dielectric material layer, thereby producing a strong localized electromagnetic field (EM) directed toward the numerical aperture of the microscope Raman spectrometer. The microscale resonator antenna array amplifies the Raman Stokes intensity at low concentrations of furfural owing to its elevated reflection coefficient throughout the whole Raman shift bandwidth. The hydrophobic absorbent property and low thermal conductivity of the monolith Si-aerogel markedly improve the detection of highly diluted furfural in aqueous solutions by drawing analytes toward the electric field hotspot of the SERS chip. In contrast to nano silver thin film-SERS, each Raman shift bandwidth of furfural can be clearly identified without spectral interference from xylitol. The microscale Si-aerogel SERS device generates a measurable Raman signal with an analytical enhancement factor (AEF) of up to 584, contingent upon the shift number, in comparison to an optical mirror.

Graphene is used in a variety of chemical, thermal, mechanical, and electrical applications. It contains one carbon atomic slide. This paper proposes a graphene-based plasmonic antenna array for THz applications. Additionally, the THz SPP waves (Surface Plasmon Polariton) phenomenon in graphene is shown. The proposed antenna is made up of four by six graphene patches, which are excited by a graphene Nano ribbon feeder placed on top of an alumina layer. CST 2020 software was used to simulate and study the antenna. As per the findings, the antenna operates in the frequency ranges [(2.6-10), (2.28-2.5), (1.87-2.14), and (1.4-1.6) ] THz, where S11 is equal to or less than -10 dB. The antenna's gain is high in these frequency band regions.

A synthesis method of sparse elliptical antenna arrays based on subarray division is introduced. The antenna array is divided into several subarrays to reduce design complexity and cost. Through strict mathematical derivation, the spacing of adjacent elements, array size, total element number, and the element number of each subarray are constrained simultaneously. To reduce the peak sidelobe level (PSLL) while constrain the first null beamwidth (FNBW) of the radiation pattern, the element positions, excitation of each subarray, and the element number of each subarray are optimized. Simulation results demonstrate effective sidelobe suppression. Compared with other literature, lower PSLL can be obtained under the constraint of FNBW, which shows the effectiveness of the proposed method. Also, full-wave electromagnetic simulation is carried out by CST using a half-wave dipole antenna.

A reconfigurable analog beamformer for the use case of multiband Global Navigation Satellite System (GNSS) multiantenna receiver systems is designed and tested. The beamformer board operates in all existing GNSS frequency bands. In this paper, the two commonly used GNSS bands, the E1/L1 and E5a/L5 GNSS bands at 1.575 GHz and 1.176 GHz, respectively, are studied. An analog weighting of the complex excitation of up to 14 individual channels is realized using attenuators and phase shifters, digitally controlled by proprietary PC software. We present an analysis of the relative errors between the channels and a simple calibration of constant errors which is applied and validated. The beamformer is then demonstrated in an exemplary test case, to generate an ad hoc pattern from an array of antennas.

In a 5G antenna system, the Butler Matrix (BM) plays a crucial role in antenna array beamforming, enabling efficient and accurate signal distribution to multiple antenna elements. However, the effectiveness of the conventional BM is limited by its frequency-dependent design, which restricts operation to a narrow bandwidth. While several techniques can extend the bandwidth, they often result in increased size, particularly at lower 5G frequency bands such as sub-6 GHz (3.5 GHz). This paper analyzes the frequency-dependent behaviour of a 4×4 BM, from the initial stage to the complete configuration. The study employs Stage 1 and Stage 2 structures with varying geometries to characterize phase–frequency behaviour and sensitivity. This analysis applies the phase-to-frequency gradient to establish a mathematical correlation between BM parameters, specifically electrical length and phase components. This correlation provides a foundation for the design of more complex BMs with higher numbers of elements and applicability to higher frequency bands.

ABSTRACT In this paper, a compact dual-band shared-aperture dual-polarized antenna array with electromagnetic transparent feeding networks is proposed for mobile communications. The proposed antenna array is composed of a 2 × 5 array antenna operating in the low-band (LB: 1.7–2.7 GHz), and a 3 × 8 array antenna operating in the high-band (HB: 3.3–3.8 GHz, i.e. N78 band). The electromagnetic transparent feeding network is realized by introducing interlaced narrow cavities over a frequency selective surface (FSS), and the feeding networks lie inside the interlaced narrow cavities to excite the antenna arrays. In addition, the FSS offers low-pass property in the LB and high-pass property in the HB. Therefore, the FSS efficiently suppresses the cross-band coupling between the LB and HB antenna arrays. A prototype of the dual-band antenna array with the proposed electromagnetic transparent feeding network is fabricated. Experimental results show both the LB and HB antennas exhibit stable radiation patterns, and satisfactory antenna realized gains, half-power beamwidth, and cross-polarization discriminations. Moreover, the antenna array achieves high cross-band isolation (20 ~ 35 dB) and realizes ±45° and ±60° beam scanning in the LB and HB. The proposed antenna array is expected to be used for the fifth-generation base station in the mobile environment.

ABSTRACT This paper introduces an innovative four‐channel filtering power divider with cross‐coupling, leading to the design of two Substrate integrated waveguide (SIW) filtering antenna arrays. A 2 × 2 antenna array with varying phases and multiple radiation zeros is developed, achieving a compact size and effective stopband suppression, thereby enhancing signal transmission and radiation characteristics. Experimental results reveal a S 11 ≤ −10 dB and a peak gain of 9.5 dBi within the 12–13 GHz passband, alongside the generation of five radiation zeros outside the passband. And next, the paper elaborates on the principle of harmonic suppression and its equivalent spur line structure model, incorporating these into the filtering divider. By extending the microstrip feeder and utilizing stacking technology, a 4 × 4 antenna array with a wide stopband and multiple zeros is realized, significantly improving radiation effects. Final test results indicate an in‐band peak gain of 14.1 dBi, out‐of‐band selectivity of 114.65 dBi/GHz and 67.8 dBi/GHz, and an S 11 ≤ −15 dB. The stopband extends to 1.85 f 0 with an attenuation exceeding 16.1 dBi, with the radiation direction aligning closely with simulation results. These features position the antenna as a formidable candidate in field of satellite communications.

ABSTRACT In addressing the pattern synthesis of multiconstraint thinned planar antenna arrays, existing intelligent optimization algorithms encounter limitations such as premature convergence and insufficient solution accuracy. Therefore, we propose an adaptive mutation strategy dung beetle optimizer (AMSDBO) for optimizing thinned planar antenna arrays. The AMSDBO algorithm innovatively constructs a three‐stage collaborative optimization framework, effectively achieving high‐performance design for thinned planar arrays under the constraints of fixed aperture size and sparsity rate through a parameter adaptive adjustment mechanism. Firstly, initial solutions for the dung beetle populations are generated using a chaotic mapping reverse learning (CMRL) strategy to enhance both population diversity and the quality of the initial solutions. Next, the local mutation search (LMS) mechanism is introduced. An adaptive T ‐distribution mechanism is imposed to effectively enhance the early global search capability. Then, the Lévy flight variation strategy is employed to adaptively adjust the positions of the dung beetle population in the later stages, helping the algorithm avoid local optima and accelerating convergence. Simulation results with classical test functions demonstrate that AMSDBO offers significant advantages in convergence accuracy and robustness compared to traditional algorithms (DBO, PSO, and IWO). Additionally, two sets of typical planar thinned array experimental results indicate that the optimization performance of the AMSDBO algorithm is significantly improved compared to traditional optimization algorithms. Specifically, there is a peak sidelobe level (PSLL) reduction of 15.5% for DBO, 11.64% for PSO, and 14.56% for IWO. This confirms the effectiveness and superiority of the AMSDBO algorithm.