Electronics

Research

15 pages, 42374 KiB

Open AccessArticle

Twelve-Element MIMO Wideband Antenna Array Operating at 3.3 GHz for 5G Smartphone Applications

by Hehe Yu, Xinwen Shang, Qianzhong Xue, Haibing Ding, Jing Wang, Weiwei Lv and Yuanzhe Luo

Electronics 2024, 13(18), 3585; https://doi.org/10.3390/electronics13183585 - 10 Sep 2024

Viewed by 768

This work presents a 12-element multiple-input–multiple-output (MIMO) wideband antenna array for mobile smartphones. The antenna element is mainly composed of two parts, greatly improving the antenna array bandwidth: one is a meandering, looped radiating element and the other is a U-shaped slot. For [...] Read more.

This work presents a 12-element multiple-input–multiple-output (MIMO) wideband antenna array for mobile smartphones. The antenna element is mainly composed of two parts, greatly improving the antenna array bandwidth: one is a meandering, looped radiating element and the other is a U-shaped slot. For the antenna element design, the meandering, looped radiating element measures 12.95 × 6 mm², while the U-shaped slot has a size of 15 × 3 mm². Meanwhile, the reflection coefficient indicates that the designed antenna array operates at 3.3 GHz with a bandwidth of 500 MHz; the transmission coefficient shows that the isolation between the antenna elements is better than 12 dB. In addition, more antenna array performances are presented, including nearly omnidirectional radiation characteristics, antenna efficiency ranging from approximately 17 to 60%, envelope correlation coefficients (ECCs) below 0.065, and diversity gain (DG) values of the MIMO antenna system close to 10 dB. The measurement results are highly consistent with the simulation results of the designed wideband antenna array, indicating its great potential for future practical engineering applications. Full article

(This article belongs to the Special Issue Antenna Design and Its Applications)

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20 pages, 11618 KiB

Open AccessArticle

MmWave Tx-Rx Self-Interference Suppression through a High Impedance Surface Stacked EBG

by Adewale K. Oladeinde, Ehsan Aryafar and Branimir Pejcinovic

Electronics 2024, 13(15), 3067; https://doi.org/10.3390/electronics13153067 - 2 Aug 2024

Viewed by 942

Abstract

This paper proposes a full-duplex (FD) antenna design with passive self-interference (SI) suppression for the 28 GHz mmWave band. The reduction in SI is achieved through the design of a novel configuration of stacked Electromagnetic Band Gap structures (EBGs), which create a high [...] Read more.

This paper proposes a full-duplex (FD) antenna design with passive self-interference (SI) suppression for the 28 GHz mmWave band. The reduction in SI is achieved through the design of a novel configuration of stacked Electromagnetic Band Gap structures (EBGs), which create a high impedance path to travelling electromagnetic waves between the transmit and receive antenna elements. The EBG is composed of stacked patches on layers 1 and 2 of a four-layer stack-up configuration. We present the design, optimization, and prototyping of unit antenna elements, stacked EBGs, and integration of stacked EBGs with antenna elements. We also evaluate the design through both HFSS (High Frequency Structure Simulator) and over-the-air measurements in an anechoic chamber. Through extensive evaluations, we show that (i) compared to an architecture that does not use EBGs, the proposed novel stacked EBG design provides an average of 25 dB of additional reduction in SI over 1 GHz of bandwidth, (ii) unit antenna element has over 1 GHz of bandwidth at −10 dB return loss, and (iii) HFSS simulations show close correlation with actual measurement results; however, measured results could still be several dB lower or higher than predicted simulation results. For example, the gap between simulated and measured antenna gains is less than 1 dB for 26–28 GHz and 28.5–30 GHz frequencies, but almost 3 dB for 28–28.5 GHz frequency band. Full article

(This article belongs to the Special Issue Antenna Design and Its Applications)

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10 pages, 3310 KiB

Open AccessCommunication

A Low-Profile Wide-Angle Coverage Antenna

by Jingli Guo, Huanhuan Zhang, Wenhao Liao, Youhuo Huang and Lanying Qu

Electronics 2024, 13(14), 2749; https://doi.org/10.3390/electronics13142749 - 12 Jul 2024

Viewed by 646

Abstract

A low-profile wide-angle coverage antenna for Ad Hoc communication networks is presented in this letter, which consists primarily of a rotationally symmetrical structure with a microstrip patch antenna positioned at its center. Utilizing two orthogonal coupling feeds, the microstrip antenna produces circularly polarized [...] Read more.

A low-profile wide-angle coverage antenna for Ad Hoc communication networks is presented in this letter, which consists primarily of a rotationally symmetrical structure with a microstrip patch antenna positioned at its center. Utilizing two orthogonal coupling feeds, the microstrip antenna produces circularly polarized radiation in the broadside direction. Meanwhile, the rotationally thin structure is driven by the coupling of the microstrip patch, and a linearly polarized radiation out of the range of ±15° is generated. Due to this parasitic structure, the radiation of the whole antenna at the upper hemisphere is balanced greatly, which leads to the wide-angle coverage ability enhancement of the low-profile antenna. A prototype operating at 2.7 GHz is fabricated and tested, demonstrating an impedance bandwidth of 15% (2.4 to 2.8 GHz). Measurement results show a 6 dB difference between the maximum and minimum gain in the upper hemisphere. With an overall antenna height of just 6 mm, all gains in the upper hemisphere exceed −3.5 dB. Full article

(This article belongs to the Special Issue Antenna Design and Its Applications)

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10 pages, 722 KiB

Open AccessArticle

Effects of Fractional Time Delay as a Low-Power True Time Delay Digital Beamforming Architecture

by Zachary Liebold, Bob Broughton and Corey Shemelya

Electronics 2024, 13(14), 2723; https://doi.org/10.3390/electronics13142723 - 11 Jul 2024

Viewed by 1061

Abstract

True time delay digital beamforming enables large squint-free bandwidths and high beamcounts, ideal for Low Earth Orbit (LEO) satellite communication links. This work proposes a true time delay architecture using Variable Fractional Delay (VFD). True time delay eliminates many analog beamforming performance constraints [...] Read more.

True time delay digital beamforming enables large squint-free bandwidths and high beamcounts, ideal for Low Earth Orbit (LEO) satellite communication links. This work proposes a true time delay architecture using Variable Fractional Delay (VFD). True time delay eliminates many analog beamforming performance constraints including inaccurate beam steering and limited beamcounts, while managing system quantization error. This article presents a method of implementing true time delay using a VFD digital filter with sufficient time resolution to minimize quantization error and enable both gigahertz bandwidths and sampling frequencies. Simulations of antenna patterns utilizing the proposed VFD digital filters demonstrate satisfactory LEO beamforming performance with only a 29-tap filter. The VFD filter was implemented using a Xilinx Virtex Ultrascale FPGA and demonstrated a 1077% reduction in dynamic power and a minimum 498% reduction in logic resources, with only a modest increase in multipliers required when compared to Farrow-based architectures previously proposed in the literature. Full article

(This article belongs to the Special Issue Antenna Design and Its Applications)

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(a): Antenna patterns for two independent systems steering to <math display="inline"><semantics> <msub> <mi>θ</mi> <mrow> <mi>R</mi> <mi>E</mi> <mi>S</mi> </mrow> </msub> </semantics></math>, 10 GHz <math display="inline"><semantics> <msub> <mi>F</mi> <mi>s</mi> </msub> </semantics></math>, and 4 GHz signal. Ideal fractional delay (orange) vs. integer only delays (blue), and (b): FIR impulse response with 0 sample fractional delay (top) vs. 0.4 sample fractional delay (bottom). Full article ">Figure 2
(a): Group delay response for an FIR filter of <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>=</mo> <mn>5</mn> </mrow> </semantics></math>. Solid trace represents 0 fractional delay and dashed traces represent <math display="inline"><semantics> <mrow> <mo>±</mo> <mn>0.5</mn> </mrow> </semantics></math> sample fractional delay. Arrow denotes sign reversal of the implemented fractional delay. Black dashed line denotes desired functional bandwidth. Red dashed line denotes filter cutoff frequency. (b): Left: filter group delay for a +0.5 sample filter for a range of N. Right: range of fractional group delay values from −0.5 to +0.5 samples for a range of N. Full article ">Figure 3
Block diagram of proposed architecture. Full article ">Figure 4
Implemented architecture in SIMULINK. Full article ">Figure 5
Antenna pattern of proposed architecture when steering to <math display="inline"><semantics> <msub> <mi>θ</mi> <mrow> <mi>Q</mi> <mi>S</mi> <mi>L</mi> <mi>L</mi> </mrow> </msub> </semantics></math>. Arrow denotes worst-case quantization sidelobe. Full article ">Figure 6
Beamsquint investigation of the proposed architecture. Full article ">

11 pages, 3972 KiB

Open AccessArticle

Folded Narrow-Band and Wide-Band Monopole Antennas with In-Plane and Vertical Grounds for Wireless Sensor Nodes in Smart Home IoT Applications

by Mohammad Mahdi Honari, Seyed Parsa Javadi and Rashid Mirzavand

Electronics 2024, 13(12), 2262; https://doi.org/10.3390/electronics13122262 - 8 Jun 2024

Viewed by 1148

Abstract

This article presents two monopole antennas with an endfire radiation pattern in the UHF band that can be installed on dry walls or metallic cabinets as a part of wireless sensor nodes, making them a suitable choice for smart home applications, such as [...] Read more.

This article presents two monopole antennas with an endfire radiation pattern in the UHF band that can be installed on dry walls or metallic cabinets as a part of wireless sensor nodes, making them a suitable choice for smart home applications, such as the wireless remote control of house appliances. Two different antennas are proposed to cover the RFID bands of North America (902–928 MHz) and worldwide (860–960 MHz). The antennas have wide horizontal radiation patterns that provide great reading coverage in their communication with a base station placed at a certain distance from the antennas. The structures have two ground planes, one in-plane and the other vertical. The vertical ground helps the antenna to have a directive radiation and also makes it easily installed on walls. The antenna feeding line lies over the vertical ground substrate. The maximum dimensions of the narrow-band antenna are L × W = 0.3

λ \times

0.14

λ

, and those for the wide-band antenna are L × W = 0.39

λ \times

0.14

λ

. The measured results show that the bandwidth of the proposed antennas for the North America and worldwide RFID bands are from 902 MHz to 939 MHz and 822 MHz to 961 MHz, with maximum gains of 4.2 dBi and 4.9 dBi, respectively. Full article

(This article belongs to the Special Issue Antenna Design and Its Applications)

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An array of sensors connected to a central hub, forming a smart home network. Full article ">Figure 2
Monopole antennas with sensing circuits: (a) antenna with in-plane ground, and (b) antenna with vertical ground. Full article ">Figure 3
Proposed antenna structures, (a) narrowband antenna, and (b) wideband antenna. Full article ">Figure 4
The Effect of length of ground plane on resonant frequency in designing narrow-band antenna, (a) different Ls while L = 100 mm, and (b) different L and Ls while L − Ls = 81.5 mm. Full article ">Figure 5
The effect of length of the antenna trace on resonant frequency in designing wideband antenna, (a) different Lf while L = 130 mm, Lt1 = 122 mm, and Lt2 = 82 mm, and (b) different Lt2 while L = 130 mm, Lt1 = 122 mm, and Lf = 86 mm. Full article ">Figure 6
Surface current of the wide-band monopole antenna at (a) first resonant frequency (873 MHz) and (b) second resonant frequency (938 MHz). Full article ">Figure 7
Radiation efficiency of both narrow-band and wide-band antennas. Full article ">Figure 8
(a) Fabricated narrow-band and wide-band monopole antennas and (b) antenna pattern measurement setup. Full article ">Figure 9
Reflection coefficient and antenna gain of the proposed antennas, (a) narrow-band monopole antenna, and (b) wide-band monopole antenna. Full article ">Figure 10
Radiation patterns of the proposed antennas at 915 MHz, (a) narrow-band monopole antenna, and (b) wide-band monopole antenna. Full article ">

16 pages, 6827 KiB

Open AccessArticle

Frequency Diversity Arc Array with Angle-Distance Two-Dimensional Broadening Null Steering for Sidelobe Suppression

by Wei Xu, Ying Tian, Pingping Huang, Weixian Tan and Yaolong Qi

Electronics 2024, 13(9), 1640; https://doi.org/10.3390/electronics13091640 - 24 Apr 2024

Cited by 1 | Viewed by 774

Abstract

The frequency diversity arc array (FDAA) improves the structure of the traditional frequency diversity array (FDA) from a linear array structure to an arc array structure, so that the FDAA not only has the advantages of the FDA but also has a large [...] Read more.

The frequency diversity arc array (FDAA) improves the structure of the traditional frequency diversity array (FDA) from a linear array structure to an arc array structure, so that the FDAA not only has the advantages of the FDA but also has a large angle and omnidirectional scanning capability. However, when it is equivalent to a linear array, this arc-shaped structure will lead to the phenomenon of inverse density weighting, which leads to a higher sidelobe level of the FDAA beam pattern. In order to solve the problem of a high sidelobe level at a certain position of the FDAA, a frequency diversity arc array with angle-distance two-dimensional broadening null steering is proposed for sidelobe suppression. Using a structural model of the FDAA, the problem of the high sidelobe was analyzed. The linear constrained minimum variance (LCMV) method was used to generate a null with a certain width at the position of the fixed strong sidelobe level in the angle domain and the distance domain of the FDAA beam pattern, to reduce the FDAA sidelobe level. Then, the angle domain and distance domain fixed positions of the FDAA were simulated to generate the null beam pattern. The simulation results verified the effectiveness of this method for reducing the sidelobe level. Full article

(This article belongs to the Special Issue Antenna Design and Its Applications)

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20 pages, 22893 KiB

Open AccessArticle

Dual-Band 2 × 1 Monopole Antenna Array and Its MIMO Configuration for WiMAX, Sub-6 GHz, and Sub-7 GHz Applications

by Sanaa Iriqat, Sibel Yenikaya and Mustafa Secmen

Electronics 2024, 13(8), 1502; https://doi.org/10.3390/electronics13081502 - 15 Apr 2024

Cited by 5 | Viewed by 1617

Abstract

This study introduces a cost-effective monopole antenna array and its MIMO configuration. The single element consists of a rectangular patch monopole featuring five circular slots at the center, accompanied by two thin slots at the top, offering a wide bandwidth (2–7.62 GHz) and [...] Read more.

This study introduces a cost-effective monopole antenna array and its MIMO configuration. The single element consists of a rectangular patch monopole featuring five circular slots at the center, accompanied by two thin slots at the top, offering a wide bandwidth (2–7.62 GHz) and a peak gain of 3.8 dBi. For gain improvement, a 2 × 1 antenna array is demonstrated. This antenna array exhibits dual-band behavior; spans from 2 to 3.71 GHz and from 5.9 to 7.54 GHz; covers the 2.5 GHz band (2.3–2.7 GHz), a significant portion of the n78 band (3.3–3.71 GHz), and the n96 band (5.925–7.125 GHz); and is assigned to WiMAX, sub-6 GHz, and sub-7 GHz applications, respectively. The antenna array achieves a peak gain of 6.47 dBi. Lastly, a two-element MIMO configuration derived from the 2 × 1 array is designed. Implementing a defected ground structure (DGS) on the ground plane plays a crucial role in enhancing the isolation from 7 dB to 20 dB. The presented MIMO antenna covers the desired frequency bands of 2.5 GHz, n78, and n96 with a peak gain of 7.5 dBi and high radiation efficiency (<99%), which qualifies it for WiMAX, sub-6 GHz, and sub-7 GHz applications. Full article

(This article belongs to the Special Issue Antenna Design and Its Applications)

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17 pages, 12998 KiB

Open AccessArticle

Multipolar Photoconductive Antennas for THz Emission Driven by a Dual-Frequency Laser Based on Transverse Modes

by Alaeddine Abbes, Annick Pénarier, Philippe Nouvel, Arnaud Garnache and Stéphane Blin

Electronics 2023, 12(22), 4679; https://doi.org/10.3390/electronics12224679 - 17 Nov 2023

Viewed by 1355

Abstract

Continuous-wave tunable photonics-based THz sources present limited output power due to the restricted input optical power accepted by photomixers, along with reduced radiation resulting from low paraxial field amplitude. Here, we investigate multipolar antenna designs to increase the available continuous-wave THz output power [...] Read more.

Continuous-wave tunable photonics-based THz sources present limited output power due to the restricted input optical power accepted by photomixers, along with reduced radiation resulting from low paraxial field amplitude. Here, we investigate multipolar antenna designs to increase the available continuous-wave THz output power by incorporating more photomixers. For this purpose, the spatial structures of the optical and THz E-fields are designed to enhance THz power and radiation in the far field. Simulations of 2 to 4 dipole antennas are conducted, demonstrating an improvement in antenna gain compared to standard dipole antennas. This is in addition to a potential increase in THz power and radiation for photomixing applications. Such work also paves the way for functionalizing the spatial structure of THz light for advanced applications. Full article

(This article belongs to the Special Issue Antenna Design and Its Applications)

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9 pages, 4004 KiB

Open AccessCommunication

A Novel Unit Classification Method for Fast and Accurate Calculation of Radiation Patterns

by Hao Zhou, Jiren Li and Kun Wei

Electronics 2023, 12(16), 3512; https://doi.org/10.3390/electronics12163512 - 19 Aug 2023

Cited by 1 | Viewed by 1337

Abstract

This paper proposes a novel unit classification technique to enhance the accuracy of the conventional pattern multiplication method by taking the mutual coupling effect and edge effect into consideration. The proposed technique classifies antenna elements into different groups based on their positions in [...] Read more.

This paper proposes a novel unit classification technique to enhance the accuracy of the conventional pattern multiplication method by taking the mutual coupling effect and edge effect into consideration. The proposed technique classifies antenna elements into different groups based on their positions in arrays, specifically corner, edge, and inner groups. By simulating the radiation patterns of antenna elements with different boundary conditions, the pattern multiplication method is then used to calculate the radiation pattern of the antenna array based on the simulated results. Several numerical examples, including a square array, a hexagonal array, and a phased array, are provided to validate the effectiveness of the proposed method. The numerical results demonstrate that the proposed method not only reduces the computational time and memory usage but also significantly improves the accuracy. The proposed method provides a powerful tool for synthesizing and predicting the radiation pattern of array antennas and offers new avenues for optimizing array antennas and phased array antennas. Full article

(This article belongs to the Special Issue Antenna Design and Its Applications)

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20 pages, 7031 KiB

Open AccessArticle

Bifocal Dual Reflectarray with Curved Main Surface

by Antonio Pino, Yolanda Rodriguez-Vaqueiro, Eduardo Martinez-de-Rioja, Daniel Martinez-de-Rioja, Borja González-Valdés, Marcos Arias, Oscar Rubiños, José Antonio Encinar and Giovanni Toso

Electronics 2023, 12(12), 2619; https://doi.org/10.3390/electronics12122619 - 10 Jun 2023

Cited by 1 | Viewed by 1218

Abstract

This paper presents a novel approach to synthesizing curved reflectarrays using Geometrical Optics (GO). It introduces the concepts of virtual normal and path length shift, which enable a vector-based formulation of the problem that can be solved using ray tracing techniques. The formulation [...] Read more.

This paper presents a novel approach to synthesizing curved reflectarrays using Geometrical Optics (GO). It introduces the concepts of virtual normal and path length shift, which enable a vector-based formulation of the problem that can be solved using ray tracing techniques. The formulation is applied for the design of two different versions of a Dual Bifocal Reflectarray with a parabolic main surface and a flat subreflectarray. The first version aims to enhance the performance of the multibeam antenna by providing a focal ring located at the feed cluster plane. The second version focuses on improving the scanning characteristics of the antenna in the horizontal plane by incorporating two foci. The synthesis procedure yields samples of the path length shift or its derivatives. To reconstruct the phase distribution, an interpolation scheme is employed and described in this paper. Numerical results are presented for both the focal-ring and two-foci configurations, demonstrating the feasibility of this solution for multibeam or scanning satellite antennas operating in the Ka. Full article

(This article belongs to the Special Issue Antenna Design and Its Applications)

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15 pages, 5163 KiB

Open AccessArticle

Beampattern Synthesis and Optimization for Frequency Diverse Arc Array Based on the Virtual Element

by Wei Xu, Zhuo Deng, Pingping Huang, Weixian Tan and Zhiqi Gao

Electronics 2023, 12(10), 2231; https://doi.org/10.3390/electronics12102231 - 14 May 2023

Cited by 5 | Viewed by 1645

Abstract

With its special, arch-shaped array structure, a frequency diverse arc array (FDAA) can perform beam scanning in 360 degrees in azimuth and in arbitrary ranges by selectively activating array elements in different positions, utilizing array element phase compensation, and adopting a frequency offset [...] Read more.

With its special, arch-shaped array structure, a frequency diverse arc array (FDAA) can perform beam scanning in 360 degrees in azimuth and in arbitrary ranges by selectively activating array elements in different positions, utilizing array element phase compensation, and adopting a frequency offset design. In this paper, a beampattern synthesis and optimization method for FDDA using the virtual array element based on the geometric configuration of FDDA is proposed. First, the position of the virtual array element is determined by the direction of the target, and then activated array elements are selected. Afterwards, the frequency offset of each array element is set up on the equiphase surface to obtain the dot-shaped beampattern. Finally, amplitude weighting is introduced to suppress the increased sidelobe level of the dot-shaped beampattern, which is caused by inverse density weighting of the arch-shaped array structure. Simulation results validate the proposed method for beampattern synthesis and optimization in FDAA. Full article

(This article belongs to the Special Issue Antenna Design and Its Applications)

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13 pages, 2639 KiB

Open AccessArticle

Data-Driven Surrogate-Assisted Optimization of Metamaterial-Based Filtenna Using Deep Learning

by Peyman Mahouti, Aysu Belen, Ozlem Tari, Mehmet Ali Belen, Serdal Karahan and Slawomir Koziel

Electronics 2023, 12(7), 1584; https://doi.org/10.3390/electronics12071584 - 28 Mar 2023

Cited by 15 | Viewed by 2611

Abstract

In this work, a computationally efficient method based on data-driven surrogate models is proposed for the design optimization procedure of a Frequency Selective Surface (FSS)-based filtering antenna (Filtenna). A Filtenna acts as a module that simultaneously pre-filters unwanted signals, and enhances the desired [...] Read more.

In this work, a computationally efficient method based on data-driven surrogate models is proposed for the design optimization procedure of a Frequency Selective Surface (FSS)-based filtering antenna (Filtenna). A Filtenna acts as a module that simultaneously pre-filters unwanted signals, and enhances the desired signals at the operating frequency. However, due to a typically large number of design variables of FSS unit elements, and their complex interrelations affecting the scattering response, FSS optimization is a challenging task. Herein, a deep-learning-based algorithm, Modified-Multi-Layer-Perceptron (M2LP), is developed to render an accurate behavioral model of the unit cell. Subsequently, the M2LP model is applied to optimize FSS elements being parts of the Filtenna under design. The exemplary device operates at 5 GHz to 7 GHz band. The numerical results demonstrate that the presented approach allows for an almost 90% reduction of the computational cost of the optimization process as compared to direct EM-driven design. At the same time, physical measurements of the fabricated Filtenna prototype corroborate the relevance of the proposed methodology. One of the important advantages of our technique is that the unit cell model can be re-used to design FSS and Filtenna operating various operating bands without incurring any extra computational expenses. Full article

(This article belongs to the Special Issue Antenna Design and Its Applications)

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