Research

10 pages, 7529 KiB

Open AccessArticle

Experimental Investigation of Reflectarray Antennas for High-Power Microwave Applications

by Jianing Zhao, Yongzhen Dong, Hao Li, Tianming Li, Wei Liu, Yihong Zhou, Haiyang Wang, Biao Hu, Fang Li, Keqiang Wang and Bin Qiu

Micromachines 2024, 15(3), 399; https://doi.org/10.3390/mi15030399 - 15 Mar 2024

Viewed by 594

Abstract

The power capacity of reflectarray antennas (RAs) is investigated through full-wave simulations and high-power microwave (HPM) experiments in this paper. In order to illustrate the results in detail, two RA elements are designed. The simulated power handling capacity of two RA elements are [...] Read more.

The power capacity of reflectarray antennas (RAs) is investigated through full-wave simulations and high-power microwave (HPM) experiments in this paper. In order to illustrate the results in detail, two RA elements are designed. The simulated power handling capacity of two RA elements are 7.17 MW/m² and 2.3 GW/m², respectively. To further study the HPM RA, two RA prototypes operating at 2.8 GHz are constructed with the aperture size of 1 m × 1 m. Simulations and experimental measurements are conducted for the two prototypes. The experimental results demonstrate that, even when subjected to 1 GW of power, the radiation beam of the RA with the second elements can still propagate in the intended direction. This research will establish a basis for advancing the practicality of RAs in HPM applications. Full article

(This article belongs to the Special Issue Advanced Antenna System: Structural Analysis, Design and Application)

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14 pages, 16838 KiB

Open AccessArticle

A Broadband Transmitarray Antenna Using a Metasurface-Based Element for Millimeter-Wave Applications

by Yue Cao, Miaojuan Zhang, Chong Fan and Jian-Xin Chen

Micromachines 2024, 15(3), 383; https://doi.org/10.3390/mi15030383 - 13 Mar 2024

Viewed by 642

Abstract

In this manuscript, a broadband transmitarray antenna (TA) using a metasurface-based element is presented for millimeter-wave communication applications. The metasurface-based TA element adopts a receiver–transmitter configuration: metasurfaces are applied as the receiver and transmitter, and slot-coupled differentially fed striplines are used as the [...] Read more.

In this manuscript, a broadband transmitarray antenna (TA) using a metasurface-based element is presented for millimeter-wave communication applications. The metasurface-based TA element adopts a receiver–transmitter configuration: metasurfaces are applied as the receiver and transmitter, and slot-coupled differentially fed striplines are used as the phase compensation. The designed TA element achieves good transmission performance with a more than 360° transmission phase shift range and less than 1-dB transmission insertion loss within a wide frequency range. To verify the proposed TA, a prototype is fabricated based on the conventional printed circuit board (PCB) process, and a pyramid horn is designed as the source. The measured results show that the proposed TA with the differential feed network presents a 1-dB gain bandwidth of 26.2% from 23.5 to 30.5 GHz and a peak gain of 24.5 dBi. The designed TA is a promising alternative for millimeter-wave communications applications because of its high gain, broad bandwidth, low costs, and convenient integration with other circuits. Full article

(This article belongs to the Special Issue Advanced Antenna System: Structural Analysis, Design and Application)

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12 pages, 13164 KiB

Open AccessArticle

Single-Layer Wide-Angle Scanning Linear Phased Arrays Based on Multimode Microstrip Patch Elements

by Dongsheng Li, Jie Yang, Jianing Zhao, Yongzhen Dong, Hao Li, Tianming Li, Haiyang Wang, Biao Hu, Yihong Zhou, Fang Li and Ruoyang Yang

Micromachines 2024, 15(1), 3; https://doi.org/10.3390/mi15010003 - 19 Dec 2023

Viewed by 734

Abstract

This paper introduces a novel single-layer microstrip patch element designed to achieve a wide beamwidth, in order to address the growing demand for wide-angle scanning capabilities in modern phased array systems. The proposed element, comprising a slot-etched circular patch and an array of [...] Read more.

This paper introduces a novel single-layer microstrip patch element designed to achieve a wide beamwidth, in order to address the growing demand for wide-angle scanning capabilities in modern phased array systems. The proposed element, comprising a slot-etched circular patch and an array of metallized holes arranged in square rings, offers a unique approach to beam shaping. By carefully adjusting parameters such as the slot structure and feeding position, our element is engineered to simultaneously excite both the TM₀₁ and TM₂₁ modes, a key feature that contributes to its wide beamwidth characteristics. Through the constructive interference of these modes, our element demonstrates a remarkable 3 dB beamwidth of approximately 150° in both principal planes, showcasing its potential for wide-angle scanning applications. To validate the practical performance of this proposed element, two linear phased arrays are manufactured and experimentally evaluated. The simulation results confirm the wide-angle scanning capability of the antennas in both the E-plane and H-plane. Furthermore, the experimental assessment demonstrates that these linear phased arrays can effectively generate scanning beams within a frequency range of 25 GHz to 28 GHz, covering a wide angular range from −60° to 60°, while maintaining a gain loss within 3 dB. This innovative design approach not only offers a promising solution for achieving a wide beamwidth in microstrip patch elements, but also holds significant potential for the development of cost-effective phased arrays with wide-angle scanning capabilities, making it a valuable contribution to the advancement of phased array technology. Full article

(This article belongs to the Special Issue Advanced Antenna System: Structural Analysis, Design and Application)

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14 pages, 5763 KiB

Open AccessArticle

Miniaturized Broadband Bi-Yagi Antenna Array for Ambient RF Energy Harvesting

by Zaed S. A. Abdulwali, Ali H. Alqahtani, Yosef T. Aladadi, Majeed A. S. Alkanhal, Yahya M. Al-Moliki, Khaled Aljaloud and Mohammed Thamer Alresheedi

Micromachines 2023, 14(12), 2181; https://doi.org/10.3390/mi14122181 - 30 Nov 2023

Viewed by 731

Abstract

This paper presents a miniaturized broadband Bi-Yagi antenna array that covers a bandwidth from 1.79 GHz to 2.56 GHz. The proposed antenna achieves a tradeoff between maximizing bandwidth, effective area, and gain while minimizing physical dimensions. The antenna design considers the coupling between [...] Read more.

This paper presents a miniaturized broadband Bi-Yagi antenna array that covers a bandwidth from 1.79 GHz to 2.56 GHz. The proposed antenna achieves a tradeoff between maximizing bandwidth, effective area, and gain while minimizing physical dimensions. The antenna design considers the coupling between the radiator and director elements, resulting in increased bandwidth as the resonating modes shift apart. Additionally, the proposed design optimizes element spacing and dimensions to achieve high gain, wide bandwidth, efficient radiation, and a minimum aperture size. The proposed antenna, with physical dimensions of 138.6 mm × 47.7 mm × 1.57 mm, demonstrates gains ranging from 6.2 dBi to 9.34 dBi across the frequency range, with a total efficiency between 88% and 98%. The proposed design is experimentally validated by measuring the reflection coefficients, input impedance, gain, and normalized radiation pattern. These features make the antenna well suited for capturing and harvesting electromagnetic waves in mobile wireless and Wi-Fi applications. Full article

(This article belongs to the Special Issue Advanced Antenna System: Structural Analysis, Design and Application)

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13 pages, 6278 KiB

Open AccessArticle

Active Adjustment of the Subreflector Shape for the Large Dual-Reflector Antenna

by Binbin Xiang, Tianxiang Zheng, Wei Wang, Peiyuan Lian, Guljaina Kazezkhan, Jianping Zhou and Kai Li

Micromachines 2023, 14(10), 1893; https://doi.org/10.3390/mi14101893 - 30 Sep 2023

Cited by 1 | Viewed by 896

Abstract

A shape adjustment method for subreflectors based on minimizing the residual wavefront error of the large dual-reflector antenna is presented. This method is used to compensate for the antenna structural deformation caused by environment loading. The shape of the subreflector is adjusted using [...] Read more.

A shape adjustment method for subreflectors based on minimizing the residual wavefront error of the large dual-reflector antenna is presented. This method is used to compensate for the antenna structural deformation caused by environment loading. The shape of the subreflector is adjusted using actuators fixed under the panels. The shape adjustment response function for the subreflector shape and the actuators’ adjustment amount is established, which is based on the inverse distance weighting function, and then the control function of the subreflector shape is obtained. The actuators’ adjustment amount can be calculated using the least squares matrix transformation with the minimum residual wavefront error. Analysis of the experiment’s results shows the residual wavefront error and primary aberration are greatly reduced under different elevation angles, and the effectiveness of the proposed method is verified. Full article

(This article belongs to the Special Issue Advanced Antenna System: Structural Analysis, Design and Application)

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12 pages, 5348 KiB

Open AccessArticle

Miniaturized Low-Frequency Communication System Based on the Magnetoelectric Effect

by Guohao Zi, Zhibo Ma, Yinan Wang, Yuanhang Wang, Ziqiang Jia, Shanlin Zhao, Dishu Huang and Tao Wang

Micromachines 2023, 14(10), 1830; https://doi.org/10.3390/mi14101830 - 26 Sep 2023

Cited by 1 | Viewed by 1055

Abstract

Recently, the realization of electromagnetic wave signal transmission and reception has been achieved through the utilization of the magnetoelectric effect, enabling the development of compact and portable low-frequency communication systems. In this paper, we present a miniaturized low-frequency communication system including a transmitter [...] Read more.

Recently, the realization of electromagnetic wave signal transmission and reception has been achieved through the utilization of the magnetoelectric effect, enabling the development of compact and portable low-frequency communication systems. In this paper, we present a miniaturized low-frequency communication system including a transmitter device and a receiver device, which operates at a frequency of 44.75 kHz, and the bandwidth is 1.1 kHz. The transmitter device employs a Terfenol-D (80 mm × 10 mm × 0.2 mm)/PZT (30 mm × 10 mm × 0.2 mm)/Terfenol-D glued composite heterojunction magnetoelectric antenna and the strongest radiation in the length direction, while the receiver device utilizes a manually crafted coil maximum size of 82 mm, yielding a minimum induced electromagnetic field of 1 pT at 44.75 kHz. With an input voltage of 150 V, the system effectively communicates over a distance of 16 m in air and achieves reception of electromagnetic wave signals within 1 m in simulated seawater with a salinity level of 35% at 25 °C. The miniaturized low-frequency communication system possesses wireless transmission capabilities, a compact size, and a rapid response, rendering it suitable for applications in mining communication, underwater communication, underwater wireless energy transmission, and underwater wireless sensor networks. Full article

(This article belongs to the Special Issue Advanced Antenna System: Structural Analysis, Design and Application)

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21 pages, 43028 KiB

Open AccessArticle

A Novel Swept-Back Fishnet-Embedded Microchannel Topology

by Yan Wang, Xiaoyue Zhang, Xing Yang, Zhiji Wang, Yuefei Yan, Biao Du, Jiliang Zhang and Congsi Wang

Micromachines 2023, 14(9), 1705; https://doi.org/10.3390/mi14091705 - 31 Aug 2023

Viewed by 865

Abstract

High in reliability, multi in function, and strong in tracking and detecting, active phased array antennas have been widely applied in radar systems. Heat dissipation is a major technological barrier preventing the realization of next-generation high-performance phased array antennas. As a result of [...] Read more.

High in reliability, multi in function, and strong in tracking and detecting, active phased array antennas have been widely applied in radar systems. Heat dissipation is a major technological barrier preventing the realization of next-generation high-performance phased array antennas. As a result of the advancement of miniaturization and the integration of microelectronics technology, the study and development of embedded direct cooling or heat dissipation has significantly enhanced the heat dissipation effect. In this paper, a novel swept-back fishnet-embedded microchannel topology (SBFEMCT) is designed, and various microchannel models with different fishnet runner mesh density ratios and different fishnet runner layers are established to characterize the chip Tmax, runner Pmax, and Vmax and analyze the thermal effect of SBFEMCT under these two operating conditions. The Pmax is reduced to 72.37% and 57.12% of the original at mesh density ratios of 0.5, 0.25, and 0.125, respectively. The maximum temperature reduction figures are average with little change in maximum velocity and a small increase in maximum pressure drop across the number of fishnet runner layers from 0 to 4. This paper provides a study of the latest embedded thermal dissipation from the dimension of a single chip to provide a certain degree of new ideas and references for solving the thermal technology bottleneck of next-generation high-performance phased array antennas. Full article

(This article belongs to the Special Issue Advanced Antenna System: Structural Analysis, Design and Application)

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14 pages, 6918 KiB

Open AccessArticle

Measurement and Correction of Pointing Error Caused by Radio Telescope Alidade Deformation based on Biaxial Inclination Sensor

by Qian Xu, Fei Xue, Hui Wang and Letian Yi

Micromachines 2023, 14(7), 1283; https://doi.org/10.3390/mi14071283 - 22 Jun 2023

Viewed by 1086

Abstract

One of the key reasons for the deterioration of antenna pointing accuracy for radio telescopes is the deformation and tilt of antenna alidades, which primarily result from track unevenness and thermal gradients. A high-precision inclinometer measurement system is installed to investigate the tilt [...] Read more.

One of the key reasons for the deterioration of antenna pointing accuracy for radio telescopes is the deformation and tilt of antenna alidades, which primarily result from track unevenness and thermal gradients. A high-precision inclinometer measurement system is installed to investigate the tilt of the antenna alidade and the pointing errors caused thermally. An environment control box with a leveling base was designed to reduce the interference of the external environment, which proved to be effective in guaranteeing the zero-point stability and repeat accuracy of the inclinometer. The tilt of the alidade caused by the track unevenness was measured by a test of slowly rotating the antenna along the azimuth at windless nighttime. A 5-day antenna stationary test and a 48 h astronomical pointing error measurement were performed, which proved the inclinometer measurement system is capable of measuring the thermally induced inclinations with acceptable accuracy. Through a preliminary compensation experiment, the pointing error is compensated from 37″ to 12″, which shows that the application of the system has a good effect on improving the pointing accuracy of the antenna. The system with high measurement accuracy, good system stability, and low computational complexity, proves an effective tool for the radio telescope to solve the problem of real-time measurement and compensation for antenna pointing errors. Full article

(This article belongs to the Special Issue Advanced Antenna System: Structural Analysis, Design and Application)

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11 pages, 5285 KiB

Open AccessArticle

Dual-Band Dielectric Resonator Antenna with Filtering Features for Microwave and Mm-Wave Applications

by Mohamed Sedigh Bizan, Hassan Naseri, Peyman Pourmohammadi, Noureddine Melouki, Amjad Iqbal and Tayeb A. Denidni

Micromachines 2023, 14(6), 1236; https://doi.org/10.3390/mi14061236 - 12 Jun 2023

Cited by 3 | Viewed by 1339

Abstract

This paper presents a new design for a dual-band double-cylinder dielectric resonator antenna (CDRA) capable of efficient operation in microwave and mm-wave frequencies for 5G applications. The novelty of this design lies in the antenna’s capability to suppress harmonics and higher-order modes, resulting [...] Read more.

This paper presents a new design for a dual-band double-cylinder dielectric resonator antenna (CDRA) capable of efficient operation in microwave and mm-wave frequencies for 5G applications. The novelty of this design lies in the antenna’s capability to suppress harmonics and higher-order modes, resulting in a significant improvement in antenna performance. Additionally, both resonators are made of dielectric materials with different relative permittivities. The design procedure involves the utilization of a larger cylinder-shaped dielectric resonator (D₁), which is fed by a vertically mounted copper microstrip securely attached to its outer surface. An air gap is created at the bottom of (D₁), and a smaller CDRA (D₂) is inserted inside this gap, with its exit facilitated by a coupling aperture slot etched on the ground plane. Furthermore, a low-pass filter (LPF) is added to the feeding line of D1 to eliminate undesirable harmonics in the mm-wave band. The larger CDRA (D₁) with a relative permittivity of 6 resonates at 2.4 GHz, achieving a realized gain of 6.7 dBi. On the other hand, the smaller CDRA (D₂) with a relative permittivity of 12 resonates at a frequency of 28 GHz, reaching a realized gain of 15.2 dBi. The dimensions of each dielectric resonator can be independently manipulated to control the two frequency bands. The antenna exhibits excellent isolation between its ports, with scattering parameters (S₁₂) and (S₂₁) falling below −72/−46 dBi at the microwave and mm-wave frequencies, respectively, and not exceeding −35 dBi for the entire frequency band. The experimental results of the proposed antenna’s prototype closely align with the simulated results, validating the design’s effectiveness. Overall, this antenna design is well-suited for 5G applications, offering the advantages of dual-band operation, harmonic suppression, frequency band versatility, and high isolation between ports. Full article

(This article belongs to the Special Issue Advanced Antenna System: Structural Analysis, Design and Application)

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20 pages, 6095 KiB

Open AccessArticle

A Novel Design of Complementary Split Ring Resonator Metamaterial-Based Low-Profile MIMO Antenna with Defected Ground Structure for S/C/X/Ka Band Applications

by Meshari Alsharari, Sunil Lavadiya, Khaled Aliqab, Ammar Armghan, Malek G. Daher and Shobhit K. Patel

Micromachines 2023, 14(6), 1232; https://doi.org/10.3390/mi14061232 - 11 Jun 2023

Cited by 6 | Viewed by 1379

Abstract

The article represents the design of two port-based printed MIMO antenna structures that have the advantages of low profile, simple structure, good isolation, peak gain, directive gain, and reflection coefficient. The performance characteristics are observed for the four design structures by cropping the [...] Read more.

The article represents the design of two port-based printed MIMO antenna structures that have the advantages of low profile, simple structure, good isolation, peak gain, directive gain, and reflection coefficient. The performance characteristics are observed for the four design structures by cropping the patch region, loading the slits near the hexagonal-shaped patch, and adding and removing the slots in the ground area. The antenna provides a least reflection coefficient of −39.44 dB, a maximum electric field of patch region of 33.3 V/cm, a total gain of 5.23 dB, and good values of total active reflection coefficient and diversity gain. The proposed design provides nine bands’ response, a peak bandwidth of 2.54 GHz, and a peak bandwidth of 26.127 dB. The four proposed structures are fabricated using a low-profile material to support mass production. The comparison among simulated and fabricated structures is included to check the authenticity of the work. The performance assessment of the proposed design with other published articles is carried out for the performance observation. The suggested technique is analyzed over the wideband of frequency region 1 GHz to 14 GHz. The multiple band responses make the proposed work suitable for wireless applications in S/C/X/Ka bands. Full article

(This article belongs to the Special Issue Advanced Antenna System: Structural Analysis, Design and Application)

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17 pages, 3417 KiB

Open AccessArticle

An Online Measurement and Calibration Method for a Radio Telescope Sub-Reflector Support Structure Using Fiber Bragg Grating

by Qian Xu and Hong Bao

Micromachines 2023, 14(5), 1093; https://doi.org/10.3390/mi14051093 - 22 May 2023

Viewed by 1051

Abstract

The position and altitude of a sub-reflector have an important influence on the pointing accuracy of a radio telescope. With the increase of the antenna aperture, the stiffness of the support structure for the sub-reflector decreases. This causes deformation of the support structure [...] Read more.

The position and altitude of a sub-reflector have an important influence on the pointing accuracy of a radio telescope. With the increase of the antenna aperture, the stiffness of the support structure for the sub-reflector decreases. This causes deformation of the support structure when environmental loads, such as gravity, temperature, and wind load, are applied to the sub-reflector, which will seriously influence antenna pointing accuracy. This paper proposes an online measurement and calibration method for assessing the deformation of the sub-reflector support structure based on the Fiber Bragg Grating (FBG) sensors. Firstly, a reconstruction model between the strain measurements and the deformation displacements of a sub-reflector support structure is established based on the inverse finite element method (iFEM). In addition, a temperature-compensating device with an FBG sensor is designed to eliminate the effects of temperature variations on strain measurements. Considering the lack of the trained original correction, a non-uniform rational B spline (NURBS) curve is built to extend the sample data set. Next, a self-structuring fuzzy network (SSFN) is designed for calibrating the reconstruction model, which can further improve the displacement reconstruction accuracy of the support structure. Finally, a full-day experiment was carried out using a sub-reflector support model to verify the effectiveness of the proposed method. Full article

(This article belongs to the Special Issue Advanced Antenna System: Structural Analysis, Design and Application)

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16 pages, 30694 KiB

Open AccessArticle

A Dual-Polarized Omnidirectional Rectenna Array for RF Energy Harvesting

by Yong Wang, Ningning Lu, Hucheng Sun and Rui Ren

Micromachines 2023, 14(5), 1071; https://doi.org/10.3390/mi14051071 - 18 May 2023

Cited by 4 | Viewed by 1343

Abstract

In this paper, a dual-polarized omnidirectional rectenna array using a hybrid power-combining scheme is proposed for the applications of RF energy harvesting. In the antenna design part, two omnidirectional antenna subarrays are created to receive horizontally polarized electromagnetic (EM) waves and a four-dipole [...] Read more.

In this paper, a dual-polarized omnidirectional rectenna array using a hybrid power-combining scheme is proposed for the applications of RF energy harvesting. In the antenna design part, two omnidirectional antenna subarrays are created to receive horizontally polarized electromagnetic (EM) waves and a four-dipole subarray is produced to receive vertically polarized incoming EM waves. The two antenna subarrays of different polarizations are combined and optimized, so as to reduce the mutual influence between them. In this way, a dual-polarized omnidirectional antenna array is realized. In the rectifier design part, a half-wave rectifying structure is adopted for converting the RF energy into DC energy. Based on the Wilkinson power divider and 3-dB hybrid coupler structure, a power-combining network is designed to connect the whole antenna array and rectifiers. The proposed rectenna array is fabricated and measured under different RF energy harvesting scenarios. All simulated and measured results are in good agreement, which verifies the capabilities of the designed rectenna array. Full article

(This article belongs to the Special Issue Advanced Antenna System: Structural Analysis, Design and Application)

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10 pages, 3186 KiB

Open AccessArticle

Low-Profile and Wider-Angle Beam Tilting Parasitic Array Resonator Antenna with Optimized Deflected Ground Plane on FR-4 Substrate

by Nur Ain Fatihah Mohd Zainudin, Mohamed Nasrun Osman, Thennarasan Sabapathy, Muzammil Jusoh, Mohd Najib Mohd Yasin and Mohamad Kamal A. Rahim

Micromachines 2023, 14(4), 834; https://doi.org/10.3390/mi14040834 - 11 Apr 2023

Cited by 1 | Viewed by 1216

Abstract

A low-profile and wide-angle radiation pattern reconfigurable antenna is designed, analyzed, and fabricated for wireless sensor network (WSN) applications, which operate at a 2.5-GHz frequency. This work aims to minimize the number of switches and optimize the parasitic size and ground plane to [...] Read more.

A low-profile and wide-angle radiation pattern reconfigurable antenna is designed, analyzed, and fabricated for wireless sensor network (WSN) applications, which operate at a 2.5-GHz frequency. This work aims to minimize the number of switches and optimize the parasitic size and ground plane to achieve a steering angle of more than 30° using a low cost-high loss FR-4 substrate. The radiation pattern reconfigurability is achieved by introducing four parasitic elements surrounding a driven element. In this work, the single driven element is fed by a coaxial feed, while other parasitic elements are integrated with the RF switches on the FR-4 as the substrate with dimensions of 150 × 100 mm (1.67 × 2.5 λ_o). The RF switches of the parasitic elements are surface mounted on the substrate. By truncating and modifying the ground plane, the beam steering can be achieved at more than 30° on the xz plane. Additionally, the proposed antenna can attain an average tilt angle of more than 10° on the yz plane. The antenna is also capable of attaining other important results, such as a fractional bandwidth of 4% at 2.5 GHz and an average gain of 2.3 dBi for all configurations. By adopting the ON/OFF condition on the embedded RF switches, the beam steering can be controlled at a certain angle, thus increasing the tilting angle of the wireless sensor networks. With such a good performance, the proposed antenna has high potential to serve as a base station in WSN applications. Full article

(This article belongs to the Special Issue Advanced Antenna System: Structural Analysis, Design and Application)

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14 pages, 4660 KiB

Open AccessArticle

A Compact Circular Rectenna for RF-Energy Harvesting at ISM Band

by Lalbabu Prashad, Harish Chandra Mohanta and Heba G. Mohamed

Micromachines 2023, 14(4), 825; https://doi.org/10.3390/mi14040825 - 08 Apr 2023

Cited by 7 | Viewed by 2248

Abstract

With low-power gadgets proliferating, the development of a small, effective rectenna is crucial for wirelessly energizing devices. A simple circular patch with a partial ground plane for RF-energy harvesting at ISM (2.45 GHz) band is proposed in this work. The simulated antenna resonates [...] Read more.

With low-power gadgets proliferating, the development of a small, effective rectenna is crucial for wirelessly energizing devices. A simple circular patch with a partial ground plane for RF-energy harvesting at ISM (2.45 GHz) band is proposed in this work. The simulated antenna resonates at 2.45 GHz with an input impedance of 50 Ω and a gain of 2.38 dBi. An L-section matching a circuit with a voltage doubler is proposed to provide excellent RF-to-DC transformation efficiency at low power input. The proposed rectenna is fabricated and the results show that the return loss and realized gain have good characteristics at the ISM band with 52% of RF-to-DC transformation efficiency, with an input of 0 dBm power. The projected rectenna is apt for power-up low sensor nodes in wireless sensor applications. Full article

(This article belongs to the Special Issue Advanced Antenna System: Structural Analysis, Design and Application)

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16 pages, 8978 KiB

Open AccessArticle

Compact Sub 6 GHz Slot Multiantenna System for 5G Laptops

by Shu-Chuan Chen, Chang-Sheng Wu, Shao-Hung Cheng and Chih-Chung Lin

Micromachines 2023, 14(3), 626; https://doi.org/10.3390/mi14030626 - 09 Mar 2023

Viewed by 1412

Abstract

A sub 6 GHz dual-band closed-slot multiantenna system for 5G laptops is proposed in this paper. It was installed in a clearance space, with dimensions og 217 × 3 mm² and 1 mm away from the upper edge of the screen ground [...] Read more.

A sub 6 GHz dual-band closed-slot multiantenna system for 5G laptops is proposed in this paper. It was installed in a clearance space, with dimensions og 217 × 3 mm² and 1 mm away from the upper edge of the screen ground plane. The dimensions of the clearance space were the same as those of a multisystem consisting of six antennas. The dimensions of the single closed-slot antenna were 32 × 3 mm² (0.368

λ

× 0.034

λ

, where

λ

equals the free-space wavelength of 3450 MHz. The antenna was coupled to an asymmetric T-shaped feed-in section equipped with a chip capacitor for exciting one-half and full wavelength resonance modes of the closed-slot to encompass sub 6 GHz 3300–3600 MHz and 4800–5000 MHz dual-band operations. The design of the antenna features a long and straight slot to generate the high-order mode of the closed slot in the high-frequency (4800–5000 MHz) band (not the low-frequency (3300–3600 MHz) multiplier band). Its structure is simple, and the width of its slot is only 3 mm. The antennas were arranged to be 5 mm apart in the same direction and in parallel to form a six-antenna system in order to utilize the weak electric fields located at the two closed ends of the closed-slot structure when the closed slot was excited. It showed excellent envelope correlation coefficients (ECCs) and isolation performance without the installation of isolation elements. The measured fractional bandwidth of the antenna was 10.15% and 6.73% at the center frequencies of 3450 MHz and 4900 MHz, respectively. Its measured isolation was always over 10 dB, and the efficiency was between 46% and 76%. The ECCs of the system calculated from the measured complex E-field radiation pattern were all below 0.2, which means that it is ideal for use in laptop devices with a high screen-to-body ratio and a metal back cover. Full article

(This article belongs to the Special Issue Advanced Antenna System: Structural Analysis, Design and Application)

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20 pages, 7036 KiB

Open AccessArticle

Design and Fabrication of Compact, Multiband, High Gain, High Isolation, Metamaterial-Based MIMO Antennas for Wireless Communication Systems

by Ammar Armghan, Shobhit K. Patel, Sunil Lavadiya, Salman Qamar, Meshari Alsharari, Malek G. Daher, Ayman A. Althuwayb, Fayadh Alenezi and Khaled Aliqab

Micromachines 2023, 14(2), 357; https://doi.org/10.3390/mi14020357 - 31 Jan 2023

Cited by 10 | Viewed by 1850

Abstract

We proposed a novel approach based on a complementary split-ring resonator metamaterial in a two-port MIMO antenna, giving high gain, multiband results with miniature size. We have also analyzed a circular disk metasurface design. The designs are also defected using ground structure by [...] Read more.

We proposed a novel approach based on a complementary split-ring resonator metamaterial in a two-port MIMO antenna, giving high gain, multiband results with miniature size. We have also analyzed a circular disk metasurface design. The designs are also defected using ground structure by reducing the width of the ground plane to 8 mm and etching all other parts of the ground plane. The electric length of the proposed design is 0.5λ × 0.35λ × 0.02λ. The design results are also investigated for a different variation of complementary split-ring resonator ring sizes. The inner and outer ring diameters are varied to find the optimized solution for enhanced output performance parameters. Good isolation is also achieved for both bands. The gain and directivity results are also presented. The results are compared for isolation, gain, structure size, and the number of ports. The compact, multiband, high gain and high isolation design can apply to WiMAX, WLAN, and satellite communication applications. Full article

(This article belongs to the Special Issue Advanced Antenna System: Structural Analysis, Design and Application)

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9 pages, 6757 KiB

Open AccessArticle

Compact Wideband Self-Decoupled MIMO Antenna for 5G Communications

by Qian Li, Chencheng Wan and Gangxiong Wu

Micromachines 2022, 13(12), 2180; https://doi.org/10.3390/mi13122180 - 08 Dec 2022

Cited by 3 | Viewed by 1058

Abstract

A compact wideband self-decoupled multiple-input and multiple-output (MIMO) antenna is presented in this paper. The proposed antenna contains a pair of horizontal back-to-back elliptical tapered slots and a vertical elliptical tapered slot, which are etched on the circular metal patch. Based on characteristic [...] Read more.

A compact wideband self-decoupled multiple-input and multiple-output (MIMO) antenna is presented in this paper. The proposed antenna contains a pair of horizontal back-to-back elliptical tapered slots and a vertical elliptical tapered slot, which are etched on the circular metal patch. Based on characteristic mode analysis (CMA) and a suitable feeding structure, two desired characteristic modes (CMs) are excited. Therefore, across the entire matched bandwidth, a high level of isolation is realized without external decoupling structures. For validation, a prototype is fabricated and measured, and the measured results demonstrate that an impedance bandwidth of 3000 MHz with isolation higher than 20dB is achieved. Due to its self-decoupled property, high isolation, wide bandwidth, and compact size, the proposed antenna has excellent potential for 5G antenna array applications. Full article

(This article belongs to the Special Issue Advanced Antenna System: Structural Analysis, Design and Application)

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