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This paper presents a novel approach to optimize the thinning of an elliptical cylindrical array (ECA) composed of uniformly stimulated, isotropic antennas with the objective of achieving a directed beam characterized by a significantly reduced relative Sidelobe Level (SLL). The optimization process employs the Novel Particle Swarm Optimization (NPSO) method, which offers a fresh perspective on addressing electromagnetic optimization challenges by its ability to effectively explore solution spaces. By employing the NPSO algorithm, which emulates the collective behavior of swarming particles to search for optimal solutions, this study addresses complex optimization challenges inherent in antenna array design. This study focuses on identifying the optimal combination of ON–OFF components (use the minimum number of ON antenna elements) within the antenna array to produce a radiation pattern exhibiting the greatest decrease in SLL. Additionally, the First Null Beam Width (FNBW) is targeted for optimization without predefined values. The optimization approach also considers the effect of thinned array element spacing on the overall performance metrics. Out of total 36 elements, only 15 elements are switched ON and the remaining of the elements are OFF, so the total reduction or thinning of ECAA is 41.66%. Simulation results demonstrate that the proposed methodology enables a simultaneous reduction of more than half of the antenna array elements while achieving superior SLL minimization. This significant reduction in antenna elements not only contributes to simplifying the array design, but also enhances the array's beamforming capabilities. [ABSTRACT FROM AUTHOR]

This study presents a substrate integrated waveguide (SIW) broadband circularly polarized (CP) high‐gain low‐profile magneto‐electric dipole antenna array. The antenna array is characterized by wide impedance bandwidth (IBW), novel CP operating principle, small form factor, and good radiation performance. First, the antenna element consists of a two‐layer dielectric substrate, two pairs of magneto‐electric dipoles, and a SIW cavity coupled and fed through a cross‐shaped rectangular slit. To achieve a wide CP bandwidth (BW), a pair of magneto‐electric dipoles is rectangularly chamfered and then an "L" type parasitic patch is introduced. The simulation results show that the antenna element has an axial ratio (AR) BW of 14.2% in the 31.48–36.16 GHz range, the IBW in the 29.08–35.98 GHz range is 21.2%, and the gain is greater than 8 dBic in all bands. The antenna exhibits stable patterns and wide overlap IBW (31.48–35.98 GHz). Then, a planar 2 × 2 antenna array fed by a one‐part‐four SIW power divider was designed, fabricated, and measured. The measured results show that the array has an ARBW of 14% in the range of 31.29−35.83 GHz, an IBW of 21.8% in the range of 29.28–35.83 GHz, and a peak gain of 14.1 dBic. [ABSTRACT FROM AUTHOR]

This paper employs the Sine Cosine Algorithm, a recent meta-heuristic method, to enhance the radiation properties of concentric elliptical antenna arrays in far-field applications, such as smart grid wireless communication and the Internet of Things. It focuses on minimizing the Sidelobe Level, a key parameter in antenna radiation, to mitigate unwanted signals and interference. The proposed method, known for its global optimization effectiveness, tackles the challenge of designing sparse multiple concentric elliptical arrays. By using the Sine Cosine Algorithm, the inter-element spacing and optimal determination of amplitude coefficients are achieved, resulting in a radiation pattern with reduced sidelobe level. To showcase the adaptability and superior performance of our proposed algorithm, we systematically evaluated its effectiveness across four distinct sets of concentric elliptical antenna arrays. These arrays comprise varying numbers of elements: (6, 12, 18 elements, 6, 12, 18, 24 elements, 6, 12, 18, 24, 30 elements and 6, 12, 18, 24, 30, 36 elements) with and without a central element. Using the sine cosine algorithm, we synthesize arrays and compare their sidelobe level and First Null Beam Width values with those from recent methods. Our findings consistently shows that the proposed algorithm consistently outperforms alternatives, yielding significantly lower sidelobe level values in all comparisons. [ABSTRACT FROM AUTHOR]

With the increasing demand for accurate and robust positioning solutions, the use of GNSS antenna arrays has gained significant attention. However, their development and testing are frequently constrained by the inflexibility of traditional hardware platforms, often requiring extensive reconfiguration throughout the development cycle. This paper presents a platform based on a system on chip to develop a highly flexible software-controlled system that is capable of directly sampling up to 16 antenna elements. Multibeam digital beamforming is implemented using the available FPGA resources and the resulting signal is reproduced by the integrated DAC and can be connected to any conventional single antenna GNSS receiver. This paper presents the architecture of the platform, detailing its components and capabilities. Our experimental results demonstrate that the system can phase shift every channel with errors of less than 0.5° and can reconfigure 4 simultaneous beams of a 16-antenna array at speeds of 1.2 kHz, and 20 beams at around 400 Hz. The average delay introduced by each channel of the system is around 381 ns with a maximum deviation of 1.05 ns. The delay was also measured for the implementation using 4 beams, which achieves a slightly bigger average delay of 384.6 ns while keeping the variation to 5 to 6 ns. This system is intended to be used as the backbone for the development of antenna arrays and beamforming algorithms. Given its flexibility, it is not necessary to develop new hardware between development iterations or even for different systems, as only the software layer needs to be modified. Consequently, it is possible to expedite the development stage before producing dedicated solutions for industrial applications. [ABSTRACT FROM AUTHOR]

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Copyright of Telecommunication Engineering is the property of Telecommunication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

ABSTRACT Phased Array Systems (PASs) are extensively used in radar and telecommunication systems for diverse applications, including military surveillance and wireless broadband communication. Besides, they are becoming increasingly indispensable in modern applications such as multi‐function phased array radars for weather monitoring and aircraft tracking or high‐throughput satellite systems, which aim to provide fast broadband connectivity in remote areas. Despite the numerous advantages of phased array systems with RF phase shift, including high signal‐to‐noise and signal‐to‐interference ratios, as well as low complexity, they present a few limitations, including high cost and large chip areas. The cost and size of PASs are mainly dependent on the RF phase shifters, which are essential to their operation. This article describes the different types of phase shifters (mechanical, ferromagnetic/magnetic, electromechanical, and electronic). It compares their performance metrics, highlighting that electronic phase shifters are the most common type used in modern PASs. In this regard, a comparative study of different subcategories of electronic phase shifters, such as the switched‐type, reflective‐type, loaded‐transmission line, and vector‐sum phase shifters, are explored along with their advantages, drawbacks and state‐of‐art techniques used to address their limitations. Therefore, this article may serve as a reference for research milestones on RF phase shifters. [ABSTRACT FROM AUTHOR]

This paper presents a low‐scattering 1 × 2 patch array antenna combining resistive and coding metasurfaces (MSs) for the reduction of wideband‐backscatter. An artificial magnetic conductor technology is used to validate the proposed technique, which is fundamentally based on scattering, phase cancellation, and absorptive property of the MS. By integration of coding MS elements and an absorbent unit cell, three different array blocks are utilized to significantly reduce the monostatic and bistatic backscattered energy level from 6.5 to 16.5 GHz, as well as overall reduction from 5 to 22 GHz. Under the incidence of plane waves, various reflection phases have been observed. The diffusion of the scattering energy from the surface can be achieved by carefully choosing the phase distributions for the reflected waves. Additionally, the bistatic backscattered energy level of the prototype is realized at various frequency points. This technique is validated using artificial magnetic conductors, which uniquely combine the effects of scattering, phase cancellation, and absorption in the MS's hybrid unit cells. Further, antenna array parameters are optimized for frequency, polarization, and angular diversity, S‐parameters, radiating efficiency, reducing radar cross section (RCS) in the wideband range and ensuring robust performance. The experimental results were substantiated by simulations of the reference and proposed prototypes suggesting that the proposed prototype can be a good candidate for applications that require a low monostatic and bistatic RCS platform. [ABSTRACT FROM AUTHOR]

This paper presents a broadband magneto-electric dipole (MED) circularly polarized (CP) microstrip antenna array with continuous rotating feed (SRF). The antenna element consists of a quarter-circle ring with irregular cross slits and a rectangular patch. The energy is combined with four metallized perforations and then transmitted to the radiating block to better excite the magnetic dipole-electric dipole energy and expand the bandwidth. Then, a 2 × 2 subarray was designed to further increase the axial ratio(AR) bandwidth. Finally, a 4 × 4 circularly polarized array arranged in a diamond shape is designed to utilize sequential rotating feeds to further improve the gain for millimeter-wave applications. Simulation results show that the impedance bandwidth (IBW) of the proposed array is 54.5% (20–35 GHz), and AR bandwidth of 3 dB is 27.2% (22.2–29.2 GHz), and the maximum gain is 16 dBic. [ABSTRACT FROM AUTHOR]

Synthetic aperture interferometry (SAI) is a signal processing technique that mixes the signals collected by pairs of elementary antennas to obtain high-resolution images with the aid of a computer. This note aims at studying the effects of the distance between the synthetic aperture interferometer and an observed scene with respect to the size of the antenna array onto the imaging capabilities of the instrument. Far-field conditions and near-field ones are compared from an algebraic perspective with the aid of simulations conducted at microwave frequencies with the Microwave Imaging Radiometer by Aperture Synthesis (MIRAS) onboard the Soil Moisture and Ocean Salinity (SMOS) mission. Although in both cases the signals kept by pairs of elementary antennas are cross-correlated to obtain complex visibilities, there are several differences that deserve attention at the modeling level, as well as at the imaging one. These particularities are clearly identified, and they are all taken into account in this study: near-field imaging is investigated with spherical waves, without neglecting any terms, whereas far-field imaging approximation is considered with plane waves according to the Van–Citter Zernike theorem. From an algebraic point of view, although the corresponding modeling matrices are both rank-deficient, we explain why the singular value distributions of these matrices are different. It is also shown how the angular synthesized point-spread function of the antenna array, whose shape varies with the distance to the instrument, can be helpful for estimating the boundary between the Fresnel region and the Fraunhofer one. Finally, whatever the region concerned by the aperture synthesis operation, it is shown that the imaging capabilities and the performances in the near-field and far-field regions are almost the same, provided the appropriate modeling matrix is taken into account. [ABSTRACT FROM AUTHOR]

Summary: A broadband ±45° dual‐polarized omnidirectional array with small size is presented. A crossed‐arranged dipole element is proposed to generate a wide unidirectional radiation beam. A crossed‐arranged parasitic strip is used to dramatically widen the impedance bandwidth of the dipole element. Based on the dipole element, a rotational two‐unit subarray, which comprises a small number of dipole elements and occupies a small space, is originally proposed to generate excellent omnidirectional radiation performance. Then a four‐unit array with a simple feed network is designed based on the rotational subarray. The array obtains a wide bandwidth of 59.4% (1.55–2.86 GHz) for reflection coefficient <−10 dB and an isolation beyond 21 dB between the two polarizations. Meanwhile, a very low gain variation of below 3 dB, as well as a stable and high realized gain of 5.1 ± 0.5 dBi are achieved over the operating band. [ABSTRACT FROM AUTHOR]

The radar of the Yagi-Uda antenna array offers useful traits for the detection of stealth targets. It employs the Very High Frequency (VHF) band, which has the advantage of counteracting stealth technology, as the shape of the target and the absorbing materials used for absorbing radar signals are less efficient against VHF. Moreover, the meter wavelength enables the radar to detect targets at distances exceeding those accessible to millimeter- and centimeter-wave radars. Nevertheless, the range of detection of this type of radar remains constrained and requires further development. The majority of current research is concentrated on the signal processing aspect, with less focus being placed on the antenna array. The antenna elements represent a crucial component of the radar station. This article presents a novel development of the traditional 16-element Yagi-Uda antenna array, which is commonly used in surveillance radar systems operating at a meter frequency band. The development is achieved through a modification of the previously mentioned antenna, which aims to increase the directivity of the antenna array, with a minimum cost and the same signal processing as the original antenna array platform. An additional two-row Yagi-Uda antenna array is proposed, comprising 14 elements in each row and an associated power unit. This modification is designed to enhance the pattern characteristics of the array. Simulation and measurement results for the pattern of the antenna indicate that the achieved gain for the proposed modification is more than 3 dB in compression compared to that of the traditional 16-element array. [ABSTRACT FROM AUTHOR]

This paper introduces Craziness-based particle swarm optimization (CRPSO), an enhanced Particle Swarm Optimization method, to study the best antenna design for an Elliptical Cylindrical Array (ECA). Heuristic methods such as the PSO algorithm has two key benefits: it employs minimal control parameters and converges quickly. However, PSO performance can be, hampered by early convergence and stagnation. This study modifies the PSO algorithm to address these issues by a "craziness" factor represented by a craziness variable. The CRPSO approach to minimizing the Side Lobe Level (SLL) by determining the optimal configuration of active and inactive elements without preset, First Null Beam Width (FNBW) parameters. Additionally, SLL variation with various element spacings. Results show a significant decrease in SLL up to −42.83 dB, and comparing the results to PSO and existing literature shows superior SLL reduction. [ABSTRACT FROM AUTHOR]

Ultrawideband (UWB) time‐reversal techniques are widely used in microwave imaging systems to detect and localize breast tumors. Measuring the scattering electromagnetic fields from a breast phantom can be time‐reversed and back‐propagated to refocus on a tumor. In this study, a Debye model was applied to the breast phantom. Using the decomposition of the time‐reversal operator (TR‐DORT), images were obtained in the UWB frequency range of 3.1–10.6 GHz. The conventional TR imaging method employs the free‐space Green's function to refocus on the tumor, which degrades refocusing in a lossy and dispersive breast phantom. We propose the use of the cylindrical dyadic Green's function in a three‐layer medium for TR imaging. The excitation system consists of a circular array of spiral antennas. The imaging results of the proposed Green's function in TR‐DORT were subsequently calculated, indicating successful tumor detection in different application scenarios of the lossy and dispersive breast phantom. [ABSTRACT FROM AUTHOR]

This paper presents the design details of an integrated 4x4 element dual feed dual circularly polarized microstrip antenna array in the S-band. The dual circular polarization is achieved by the use of quadrature hybrids. Power division for the dual input array is achieved through two 1x16 equal split equal phase corporate feed networks. The quadrature hybrids and corporate feeds for the proposed array are designed in multilayer printed circuit boards (PCB) in stripline configuration. This antenna can be used to transmit or receive both right-handed circularly polarized (RHCP) waves or left-handed circularly polarized (LHCP) waves simultaneously or one at a time by terminating the other port with 50Ω resistance. The proposed antenna has 700MHz of 10 dB impedance bandwidth (27%), 400MHz of 3dB axial ratio bandwidth and 300MHz of 3dB gain bandwidth centred at 2.5GHz with a peak gain of 15.5dB in both polarizations. It has a 3dB beam width of 26° and cross-polarization levels below 20dB in both the polarizations. Design and simulation of patch array, quadrature hybrids and 1x16 corporate feeds in multilayer configuration, PCB stack-ups, fabrication, integration and testing processes are discussed in detail. The effect of thermal protection system (TPS) of the re-entry vehicle on antenna performance parameters was studied and presented. [ABSTRACT FROM AUTHOR]

In this study, we propose a smart transfer planer equipped with multiple antenna arrays to improve ground links for low Earth orbit (LEO) satellite communication. The STP features a symmetrical structure and is strategically placed on both ends of a window, serving both indoor and outdoor environments. Using the window glass as a medium, energy transmission occurs through a coupling mechanism between the planers. The design focuses on large array antenna design, beamforming networks, and coupler design on both sides of the glass. Beamforming networks enable the indoor and outdoor antenna arrays to switch beams in various directions, optimizing high-gain antennas with narrow beamwidths. Through electromagnetic induction and filter couplers, a robust signal transmission channel is established between indoor and outdoor environments. This setup significantly enhances communication efficiency, particularly in non-line-of-sight environments. [ABSTRACT FROM AUTHOR]

A hybrid solar and RF energy harvester is proposed for applications in self-powered wireless sensor nodes. A planar slot antenna array backed by substrate integrated waveguide (SIW) cavity is produced for RF energy harvesting. A designed rectifier connected to the antenna array converts the received RF energy into DC energy. Solar cells are placed on the rest of the antenna array except slots, fully utilizing the array's surface. The solar cell coverage ratio reaches 87%. The measurement results indicate that under solar simulator illumination, the solar energy harvester has a short-circuit current of 15.7 A, an open-circuit voltage of 0.542 V, and a maximum output power of 5.81 W. Under the RF power density of 85.5 μW/cm2, the RF energy harvester reaches its peak power conversion efficiency (PCE) of 69%. All simulated and measured results are in good agreement, verifying the capabilities of the designed hybrid harvester. [ABSTRACT FROM AUTHOR]

Kidney cancer is a significant health concern worldwide, with early detection crucial for successful treatment outcomes. Recently, there has been an increasing focus on investigating affordable and non-intrusive methods for detecting cancer at its early stages. This proposed approach delves into the utilization of antenna arrays to identify kidney cancer. Specifically, antenna array with circular polarization has been crafted to identify tumors in the human kidney. This array design has been implemented using CST software, operating at 2.4 GHz. The antenna array having a dimension of 150 mm x 150 mm. The array consists of four-square patches each having a length of 30 mm and the spacing between the patches is preferred to be 20 mm for ensuring the mutual coupling. FR4 substrate is used with the relative permittivity 4.3 and 1.6 mm thickness. The axial ratio of the circularly polarized antenna is 0.9 dB at 2.4 GHz. The reflection coefficient S 11 = –30dB. The renal phantom in humans has been built with the kidney, adrenal gland, ureter, skin, fat, and muscle components to allow for precise simulation. Following that, four stages of cancer tumors were built employing all of the necessary qualities. For every stage of the cancer tumor, the reflection coefficient growth and resonance frequency shift are calculated. For the initial stages, the resonance frequency shift is very low. Consequently, the primary determinant of detection is the rise in S 11 . For 3rd and 4th stages of the tumor, there is a significant change in resonance frequency and increase S 11 , which facilitates identification. The calculated specific absorption rate (SAR) is a smaller amount than the safety thresholds, indicating that using this method is safe. Overall, this research points to a novel, easy-to-use method for kidney cancer screening. This method has the following benefits: it is non-invasive, safe, quick, affordable, and comfortable, and it emits no ionizing radiation during the measurement process. Furthermore, a range of output parameters such as gain, directivity, and polar radiation have been accurately computed. [ABSTRACT FROM AUTHOR]

Orbital Angular Momentum (OAM) waves are characterized by helical wave fronts and orthogonality between different modes. Therefore, OAM waves have huge potential in improving wireless communications' channel capacity and radar imaging's resolution. Consequently, the generation and application of OAM waves have attracted a lot of attention. And many methods are proposed to generate OAM waves. Although antenna array is the most popular method of generating OAM waves, OAM waves generated by antenna array have redundant modes. However, all advantages of OAM waves are closely related to infinite OAM modes. Thus, to better apply OAM waves to wireless communications and radar, it is very important to reduce unnecessary OAM modes and improve the OAM mode purity. In order to improve the OAM mode purity, two combined antenna arrays composed of X direction antenna and Y direction antenna array are proposed in this paper. The X direction antenna array and the Y direction antenna array are supplied by the excitations with the same amplitude and fixed phase shift. The overall phase shift of the X direction antenna array is π/2 more or less than that of the Y direction antenna array. The results of formulas and antenna models in CST show that the combined antenna arrays can generate OAM waves with less redundant modes in x component, y component and z component. Besides, the z component carries pure OAM modes.

A dual-band (K-/Ka-band) antenna array is presented. An ultra-wideband antenna element in the shape of a double-ridged waveguide is used as a radiation slot, and a novel dual-periodic ridge gap waveguide (RGW) with an interdigital-pin bed of nails (serving as a filter) is used to realize dual-band operation. By periodically arranging the pins of two different heights in two dimensions, the proposed RGW with interdigital-pin bed of nails is able to realize and flexibly adjust two passbands. The widely used GW-based back cavity boosts the realized gain and simplifies the feed network design. A 4 × 4 prototype array was designed, fabricated, and measured. The results show that the array has two operating bands at 24.5–26.4 GHz and 30.3–31.5 GHz, and the realized gain can reach 19.2 dBi and 20.4 dBi, respectively. Meanwhile, there is a very significant gain attenuation at stopband. [ABSTRACT FROM AUTHOR]

Millimeter-wave (mmWave) antenna arrays are pivotal components in modern wireless communication systems, offering high data rates and improved spectrum efficiency. However, the performance of mmWave antenna arrays can be significantly affected by structural distortions, such as mechanical deformations and environmental conditions, which may lead to deviations in beamforming characteristics and radiation patterns. In this paper, we present a comprehensive sensitivity study of mmWave antenna arrays to structural distortion, employing a coupled structural–electromagnetic statistical concept. The proposed model integrates structural analysis techniques with electromagnetic simulations to assess the impact of structural distortions on the performance of mmWave antenna arrays. In addition, the model incorporates random element positioning, making it easy to analyze radiation pattern sensitivity to structural deformation. Demonstrating the applicability of the model, a 10 × 10 microstrip patch antenna array is designed to assess the performance of the model with a random position error and saddle shape distortion. The results of the model are then compared against the acceptable results from the HFSS software (version 13.0), where a good agreement is observed between the two results. The results show the gain variation and sidelobe level under various degrees of distortion and random errors, respectively. These results provide a guide for design, deployment, and optimization of mmWave communication networks in real-world environments. In addition, the model provides valuable insights into the trade-offs between antenna performance, structural integrity, and system reliability, paving the way for more efficient and dependable mmWave communication systems in the era of 5G and beyond. [ABSTRACT FROM AUTHOR]

This paper proposes a broadband eight-antenna array design suitable for Fifth Generation New Radio (5G NR) smartphone applications. To cover the 5G NR bands n77/n78/n79 (3300–5000 MHz) and 5G NR-U n46 band (5150–5925 MHz), the single antenna array unit applied is a modified loop antenna element (MLAE) that can generate three different loop modes. To yield good multi-input multi-output (MIMO) performances, the designed MLAE is further arranged as an eight-antenna array, and the experimental results show that the overlapping 6 dB bandwidth can cover the bands-of-interest (3300–5925 MHz) with good isolation and total efficiency of >10 dB and 51–84%, respectively. Finally, good MIMO performances, such as an envelope correlation coefficient (ECC) of lower than 0.1 and desirable channel capacity (CC) of 37–40 bps/Hz, were calculated across the bands-of-interest. [ABSTRACT FROM AUTHOR]

The sine cosine algorithm (SCA), a meta‐heuristic optimization method, is used in this study to provide a precise linear and elliptical antenna array design for synthesizing the ideal far‐field radiation pattern in the fifth‐generation (5G) communication spectrum. The wireless communication system will undergo dramatic changes thanks to the forthcoming 5G technology, which offers exceptionally high data rates, increased capacity, reduced latency, and outstanding service quality. The most important component of 5G communications is an accurate antenna array design for an optimum far‐field radiation pattern synthesis with a suppressed sidelobe level (SLL) value and half power beam width (HPBW). While long‐distance communication necessitates a low HPBW, the entire side lobe area needs a suppressed SLL to prevent interference. The SCA is used in this case to the optimal feeding currents applied to each array member in the design examples of the concentric circular antenna arrays (CCAA) discussed in this article. It shows the litheness and attainment of the propound algorithm named SCA, chosen CCAAs with three rings and varying amounts of components or antenna array sets those are stated as follows: Set I (4, 6, 8 elements), Set II (8, 10, 12 elements), Set III (6, 12, 18 elements), Set IV (8, 14, 20 elements) with and without the center element are amalgamate. Apply the PSO, Jaya, and SCA optimization algorithms for all four Sets of antenna arrays and compare the attained results; the SLL values achieved by the SCA technique are contrasted with those of other current optimization techniques. The outcomes of all examinations reveal that the SCA algorithm achieved a superior SLL reduction over other optimization techniques. [ABSTRACT FROM AUTHOR]

In this research, the effectiveness of six element uniform circular uniform dipole array is designed. To determine the most productive design for the ISM Band, numerous array antenna topologies are tested in this work. The proposed antenna is appropriate for the ISM, IEEE 802.11, Bluetooth, as well as Zigbee, WiMAX, and WiFi applications. We first set up a 6-element dipole linear array for this, after which we switched to a rectangular array using a combination of triangular and rectangular lattice arrangements. The identical 6-element dipole antenna was then configured in a circular fashion, and the results appear to be excessively good when compared to all previous configurations. The symmetrical arrangement of a uniform circular array design allows the phasing of array antennas to operate azimuthally with little variation in its wavelength and side lobe intensities. There are 6 isotropic components in this uniform circular array design. To adjust the antenna to shifting surroundings, complicated values of the antennas array components are calculated. The correlation effect between various elements were analysed. In this work a return loss of – 35 dB was obtained as a maximum value for circular array configuration at 2.45 GHz. The goal of employing array antennas is to provide increased efficiency and broad band capabilities, allowing for usage in a variety of everyday applications. [ABSTRACT FROM AUTHOR]

The paper proposes a high gain, low ECC, and high isolation THz MIMO antenna array for future generation wireless applications to accommodate a growing population of mobile users. A THz MIMO antenna array is designed with dimensions of 1200 × 2200 × 191.29 µm3. It employs the array of double-slit complementary split-ring resonators (D-CSRRs) on the bottom layer to improve the gain, return loss, and isolation. The gain of the proposed antenna array is 11.3 dBi with 66.45 % radiating efficiency at 0.65 THz. The −10 dB impedance bandwidth lies from 0.62–0.66 THz. The parameters of the MIMO antenna are evaluated such as isolation, envelope correlation coefficient (ECC), diversity gain (DG), and channel capacity loss. The ECC and DG value observed are 2.84 × 10−6 and 9.98 dB, respectively, at 0.65 THz. The channel capacity loss and isolation of the proposed MIMO antenna array are below 0.4 bps/Hz and (|S21| > 25 dB), respectively, in the complete operating band. The suggested THz MIMO antenna array can be utilised for THz high-speed wireless communication, video-rate imaging systems, sensing, the medical field for cancer imaging, security scanning, and the detection of illicit goods. [ABSTRACT FROM AUTHOR]

Against the background of the intensive development and implementation of satellite technologies for position determination, navigation, and time synchronization, one of the central threats to critical industries is the creation of intentional interference to the signals of global navigation satellite systems. It is shown that the use of small-sized antenna arrays in navigation systems consisting of satellite constellations of GPS, GLONASS, GALILEO, BEIDOU, QZSS, or their combinations makes it possible to detect and suppress interfering signals by forming zeros of the antenna array directional pattern in the directions of their arrival. The interfering signal suppression is supplemented with detection procedures while maintaining the ability of navigation by using from one to four satellite systems according to criteria of the required number of satellites in the line of sight and the permissible geometric factor. The process of suppressing the interfering signal from four directions is illustrated by three scenarios, the initial data for which are signals from 35 satellites in the line of sight collected in real-time from five systems. It has been shown that the use of five systems and 35 satellites ensures the suppression of the interfering signal. At the same time, 22 satellites are involved in solving the navigation problem, 13 satellites are below the detection threshold, and the geometric factor is 1.18. When using GPS, GLONASS, and 19 satellites, the interfering signal is suppressed. In this case, 10 satellites are involved in solving the navigation problem, 9 are below the detection threshold, and the geometric factor is 2.1. When using only GPS, the interfering signal suppression is also ensured. This time 7 satellites are involved in solving the navigation problem, 4 are below the detection threshold, and the geometric factor is 1.76. [ABSTRACT FROM AUTHOR]

In this paper, an eight-port antenna array is presented for 5G handheld terminals to support multiple-input multiple-output (MIMO) operations. The reported design involves three layers: the top contains eight circular microstrip feed elements; the middle is a low-cost FR-4 substrate, and the bottom layer is a ground plane with four etched octagonal slots. Each resonating element is fed by 50-ohm sub-miniature connectors. To mitigate the detrimental effects of mutual coupling of ports and enhance overall isolation between the adjacent microstrip-fed circular patch elements, a neutralization line is strategically implemented between the feed lines of the antenna array. The design configuration involves two elements at each vertex of the printed circuit board (PCB). The overall dimensions of the PCB are 150 × 75 mm2. Each slot and its corresponding radiating elements exhibit linear dual polarization and diverse radiation patterns. The proposed antenna design achieves the required operating bandwidth of more than 1000 MHz spanning from 3 to 4.2 GHz, effectively covering all the upper C-band frequency range of 3.3 GHz to 4.2 GHz allocated for 5G n77 and n78 frequency range 1 (FR1). Required port isolation and lower envelop correlation coefficient (ECC) are achieved for the band of interest. The proposed design gives a peak gain of up to 4 dB for the said band. In addition to these results, degradation in the performance of the antenna array is also investigated during different operating modes of the handheld device. Measured results from the fabricated unit cell and whole array also have a good match with simulated results. On the whole, the proposed antenna possesses the potential to be used in 5G and the open radio access network (ORAN) compliant handheld devices. [ABSTRACT FROM AUTHOR]

With the continuous development of wireless communication technology, the frequency band of 6G communication systems is moving towards higher frequencies such as millimeter waves and terahertz. In such high-frequency situations, wireless transmission requires antenna modules to be provided with characteristics of miniaturization, high integration, and high gain, which presents new challenges to the development of antenna technology. In this article, a 4 × 4 antenna array using multilayered low-temperature co-fired ceramic is proposed, operating in W-band, with a feeding network based on substrate-integrated waveguide, and an antenna element formed through the combination of a substrate-integrated cavity and surface parasitic patches, which guaranteed the array to possess the advantages of high integration and high gain. Combined with the substrate-integrated waveguide to a rectangular waveguide transition structure designed in the early stage, a physical array with a standard metal rectangular waveguide interface was fabricated and tested. The test results show that the gain of the antenna array is higher than 18 dBi from 88 to 98 GHz, with a maximum of 20.4 dBi. [ABSTRACT FROM AUTHOR]

This study focused on the detection of water inrush in tunnels excavated by full-section hard rock tunnel boring machines (TBMs) and employed ground penetrating radar methods for conducting research on radar signal processing algorithms. The research demonstrates that conventional techniques are inadequate for eliminating the interference of TBM equipment on radar signal propagation. This study employs a radar antenna array method for signal transmission, utilizing a wavelet double-threshold filtering algorithm and wave propagation theory to suppress clutter. These methods exhibit strong signal reception capabilities and are effective in eliminating 13.1% of the direct wave components. The adoption of a novel, efficient radar signal imaging algorithm simplifies the imaging process. Results of verification indicate that the synthetic aperture algorithm, enhanced with cross-correlation calculation, yields the optimal imaging effect. This investigation, which was conducted in conjunction with the construction of a diversion tunnel in a specific region, has confirmed the applicability of the ground penetrating radar method for the detection of water inrush in TBM tunnels by conducting a comparative analysis of the direct wave removal algorithm and the integration of the optimal imaging algorithm. The innovative application of ground penetrating radar within TBM tunnels, along with a targeted technology to mitigate signal interference from metal equipment, has led to the selection of an appropriate algorithm for both signal processing and imaging. This approach offers a novel solution for the detection of water source disasters in TBM tunnels. [ABSTRACT FROM AUTHOR]

The review article summarizes the most significant results of research on the creation of antenna systems for mobile radio communications and radar, carried out at the Department of Information Radio Technologies of the Belarusian State University of Informatics and Radioelectronics over the last decade. New algorithms for the functioning of antenna matching devices for mobile radio communications in the VHF wavelength range, features of the construction of sub-aperture antenna arrays for radar equipment with broadband probing signals, and algorithms for processing signals in detectors-measurers of the angular coordinates of air objects with a multi-channel antenna system are considered. Promising areas of research on this topic are proposed.

To address the long distance and significant loss in satellite-to-ground wireless link, new demands are imposed on satellite phased arrays by direct-to-handset satellite. By analyzing the practical requirements of direct-to-handset satellite, the advantages and disadvantages of various beamforming architectures were outlined, then the proper selection strategy of beamforming architecture was proposed. Subsequently, dual-band shared-aperture circularly-polarized antenna arrays under frequency division duplexing (FDD) were discussed. In addition, the stacking and integration architecture of phased arrays was reviewed, and several key fabrication technologies for components and chips were introduced. Finally, the outlook and key technologies of satellite phased arrays for direct-to-handset satellite were presented.

This paper presents a theoretical method to estimate the pulse radiation characteristics of Vivaldi antennas. Based on the surface current distribution and the ultra-wideband radiation principle, Vivaldi antenna is equivalently modeled as a dipole array, and the pulse radiation characteristics of a single Vivaldi antenna are brought out utilizing the spatial superposition approach. Then, the influences and results of the Vivaldi antenna pulse characteristics prediction with different construction ways of the dipole array and element numbers are furthermore investigated. Next, a quadratic spatial superposition technique is employed to complete the theoretical prediction for time-domain radiation characteristics of Vivaldi antenna arrays. Experiments and simulations are conducted separately to verify the proposed method for both single Vivaldi antenna and array. The validated results demonstrate that the dipole array-based theoretical prediction method can effectively capture the pulse radiation characteristics for both individual Vivaldi antenna and array operating in different modes, thereby addressing challenges associated with estimating radiation characteristics in ultra-wideband pulse applications. [ABSTRACT FROM AUTHOR]

Focused microwave breast hyperthermia (FMBH) employs a phased antenna array to perform beamforming that can focus microwave energy at targeted breast tumors. Selective heating of the tumor endows the hyperthermia treatment with high accuracy and low side effects. The effect of FMBH is highly dependent on the applied phased antenna array. This work investigates the effect of polarizations of antenna elements on the microwave-focusing results by simulations. We explore two kinds of antenna arrays with the same number of elements using different digital realistic human breast phantoms. The first array has all the elements' polarization in the vertical plane of the breast, while the second array has half of the elements' polarization in the vertical plane and the other half in the transverse plane, i.e., cross polarization. In total, 96 sets of different simulations are performed, and the results show that the second array leads to a better focusing effect in dense breasts than the first array. This work is very meaningful for the potential improvement of the antenna array for FMBH, which is of great significance for the future clinical applications of FMBH. The antenna array with cross polarization can also be applied in microwave imaging and sensing for biomedical applications. [ABSTRACT FROM AUTHOR]

The use of equivalent sources for the analysis of antenna arrays for high computational efficiency has been proposed. A single antenna element has been designed, and the fields have been saved on an enclosed geometry. The surface equivalence principle has been utilized to calculate the far‐field patterns from the fields saved on the enclosed geometry which has been termed as Huygens' box (HB). The antenna element has been used to design 2×1 $2\times 1$, 4×1 $4\times 1$, 8×1 $8\times 1$, and 16×1 $16\times 1$ array and the far‐fields have been calculated. For linear arrays of HBs far‐field patterns and computation time have been compared with that of the actual antenna array. As the number of elements increases from 4 to 16, the computation time has been found to reduce from 6% $6 \% $ to 47% $47 \% $. Further, the computation time has been found to reduce by 39% $39 \% $ and 75% $75 \% $ for 2×2 $2\times 2$ and 4×4 $4\times 4$ configurations, respectively. The method is suitable for analysis of complex geometry of antennas used in 5G technology and beyond. [ABSTRACT FROM AUTHOR]

The widespread introduction of antenna arrays into the practice of ultrasonic testing has made it possible to obtain images of reflectors using either phased array technology or digital focusing of aperture (DFA) technology. However, many current regulatory documents governing the rules for conducting ultrasonic nondestructive testing in nuclear power engineering, petrochemistry, gas production industry, etc. require determining the equivalent dimensions of reflectors. The present article proposes a method for calculating the DAF-DGS array to determine the diameter of an equivalent flat-bottomed hole (FBH) when analyzing an image. It is shown that it is more efficient to work not with the amplitude of the image, but with the integral amplitude. Numerical experiments have shown the accuracy of the order of mm in determining the FBH diameter. In model experiments, the accuracy of determining the FBH diameter was better than 0.2 mm in absolute value. [ABSTRACT FROM AUTHOR]

This paper presents a four-port multiple-input multiple-output (MIMO) magneto-electric dipole antenna array with high gain and high isolation for 5G millimeter-wave communications. Each antenna contains an eight-way power divider, an eight-element magneto-electric dipole antenna array, a metal rectangular ring, and a dielectric slab. The proposed magneto-electric dipole antenna array has high radiation gain. The metal rectangular ring is applied to not only support the dielectric slab but suppress the surface wave propagation and thus the mutual coupling can be reduced. A further increase in the isolation performance can be realized based on the polarization diversity. The simulated and measured impedance bandwidths at 10 dB return losses are 24–31.86 GHz (28.1%) and 24.12–32 GHz (28.1%), respectively. The simulated and measured isolation levels are larger than 25 and 20 dB, respectively. The simulated and measured realized peak gains at 30 GHz are 20.5 and 19.2 dBi, respectively. [ABSTRACT FROM AUTHOR]

This paper introduces an application of the dandelion optimization (DO) algorithm in antenna arrays. This is the first time that the DO algorithm has been used for optimizing antenna arrays. For antenna array optimization, sidelobe level (SLL) and deep nulls are key technical indicators. A lower SLL can improve the signal-to-noise ratio and reduce the impact of clutter signals outside the main beam. Deep nulls need to be aligned with the direction of interference to eliminate the influence of interference sources. The combination of the two can effectively improve the anti-interference ability of the entire system. Therefore, antenna arrays with ultra-low sidelobes and ultra-deep nulls are currently hot in the field of antenna array design and are also some of the key technologies needed to achieve modern high-performance radar systems. As a new type of evolutionary algorithm inspired by nature, the DO algorithm is inspired by the wind propagation behavior of dandelions in nature. This algorithm iteratively updates the population from three stages of ascent, descent, and landing, ultimately finding the optimal position. It has good optimization ability in solving complex problems such as those involving nonlinearity, discreteness, and non-convexity, and the antenna array pattern synthesis optimization problem belongs to multivariate nonlinear problems. Therefore, the DO algorithm can be effectively applied in the field of antenna array optimization. In this work, we use the following method to obtain an optimized pattern of a linear array with the lowest sidelobe level (SLL), null placement in particular directions, and a lower notch in particular directions: by controlling the antenna array's element spacing and leaving the phase unchanged to optimize the current amplitudes and by controlling the excitation current and phase fixation of the antenna array and changing the element spacing. In the first and second examples, different algorithms are used to reduce the SLL of the antenna. In the first example, the DO algorithm reduces the SLL to −33.37 dB, which is 2.67 dB, 2.67 dB, 3.77 dB, 2.74 dB, and 2.52 dB lower than five other algorithms. In the second example, the SLL optimized by the DO algorithm is −42.56 dB, which is 5.04 dB and 1.48 dB lower than two other algorithms. In both examples, the DO algorithm reduces the SLL lower than other algorithms when the main lobe of the antenna is not significantly widened. Examples 3, 4, and 5 use the DO algorithm to optimize the amplitude of the current, generating deep nulls and deep notches in specific directions. In Example 3, the DO algorithm obtains a depth of nulls equal to −187.6 dB, which is 66.7 dB and 44.3 dB lower than that of the flower pollination algorithm (FPA) and the chaotic colony predation algorithm (CCPA), respectively. In Example 4, the deep null obtained by the DO algorithm is as low as −98.69 dB, which is 6.67 dB lower than the deep null obtained by the grey wolf optimization (GWO) algorithm. In Example 5, the deep notch obtained by the DO algorithm is as low as −63.1 dB, which is 6.4 dB and 1.9 dB lower than the spider monkey optimization (SMO) algorithm and the grasshopper optimization algorithm (GOA), respectively. The data prove that the DO algorithm produces deeper nulls and notches than other algorithms. The last two examples involve reducing sidelobe levels and generating deep nulls by optimizing the spacing between elements. In Example 5, the SLL obtained using the DO algorithm is −22.8766 dB, which is 0.1998 dB lower than the lowest SLL of −22.6768 dB among other algorithms. In Example 6, the SLL obtained using the DO algorithm is −20.1012 dB, and the null depth is −125.1 dB, which is 1.592 dB lower than the SLL obtained by the cat swarm optimization (CSO) algorithm and 19.1 dB lower than the deep null obtained by the GWO algorithm, respectively. In summary, the results of six simulation experiments indicate that the DO algorithm has better optimization ability in linear array optimization than other evolutionary algorithms. [ABSTRACT FROM AUTHOR]

This paper introduces the design of a multiple-input-multiple-output (MIMO) antenna optimized for low-profile applications supporting sub-6 GHz fifth-generation (5G) wireless applications. We have started the design from a single antenna with a square patch shape, each antenna array is composed from 4-element radiators fed by using power dividers and quarter microstrip lines. Mounted on a single Rogers RT5880 substrate, the MIMO antenna functions at 3.5 GHz. In order to miniature and to decrease the mutual coupling between the both antennas array we have optimised a magnetic wall based on periodic structures permitting to decrease the mutual coupling between the both antenna array. The unit element from the wall was optimised, studied and validated in order to absorb the surface current and to enhance the isolation between the different radiating elements. The dimensions of the proposed MIMO antenna are 154×220×0.578 mm². The MIMO antenna final circuit achieves a peak gain of 9 dBi and an isolation around -30 dB. The introduction of the magnetic wall permits to enhance the isolation between the antenna array from -20 dB to -30 dB at 3.5 GHz band. This advancement contributes to the overall performance improvement of the MIMO antenna system. [ABSTRACT FROM AUTHOR]

This work proposes a new conception of the global microstrip rectenna system operating around 2.45 GHz. This improved rectenna system associates a receiving antenna with a rectifier circuit. This rectenna is printed on an FR4 substrate. The proposed antenna is a 1x4 microstrip antenna patch array with pentagonal patches using the defective ground structure method and operates with circular polarization. To show the effectiveness of this array, the results obtained by the computer simulation technology microwave studio (CST MWS) software prove that this array is good in terms of high gain, high directivity, high efficiency, wideband, small volume, and well-adaptation, and all these results are confirmed by another solver high-frequency structure simulator (HFSS). The improved rectifier is a microstrip rectifier that uses an HSMS2852 Schottky diode by using a series topology. The effectiveness of this rectifier is proved by the simulation results using advanced design system (ADS) software in terms of well-matching input impedance, high efficiency, and important output direct current (DC) voltage value. The proposed rectenna system is more efficient compared with the existing works and is very appropriate for several applications of wireless power transmission to power supply electronic instruments in various fields cleanly on our planet. [ABSTRACT FROM AUTHOR]

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