Microwave Antennas: Theory, Material, Technology, Design and Application

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Electrical, Electronics and Communications Engineering".

Deadline for manuscript submissions: closed (31 October 2023) | Viewed by 13193

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School of Information and Commnuications Engineering, Xi’an Jiaotong University, Xi’an 710049, China
Interests: multi-functional microwave; mmWave passive components; wireless power transfer
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The Key Laboratory of RF Circuits and System of Ministry of Education, Hangzhou Dianzi University, Hangzhou, 310018, China
Interests: millimeter-wave antenna array; multi-beam antenna array; wideband antenna
Special Issues, Collections and Topics in MDPI journals

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Division of Medical Engineering Research, National Institute of Rehabilitation-LGII, México City 14389, Mexico
Interests: antenna design; antennas; cancer; image processing; bone tumors; thermal treatment; thermal therapy; microwave ablation; FEM modeling

Special Issue Information

Dear Colleagues,

We are inviting submissions to the Special Issue on Microwave Antennas, including theory, material, technology, design, and application. Microwave antennas are indispensable hardware devices in wireless communication and detection systems. The theory of microwave antennas provides researchers and engineers with convenient and concise guidance. Not limited to traditional metal and dielectric substrates, the application of new materials can improve the performance of microwave antennas. Furthermore, PCB, 3D-printing, LTCC, and other fabrication technologies will unlock the full potential of microwave antennas. The integration of antennas with other devices, and the influence of application environment are the research hotspots as well. In this Special Issue, we invite submissions exploring cutting-edge research and recent advances in the fields of microwave antennas. Both theoretical and experimental studies are welcome, as well as comprehensive review and survey papers.

Dr. Jianxing Li
Dr. Kuikui Fan
Dr. Citlalli Jessica Trujillo-Romero
Guest Editors

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Published Papers (7 papers)

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Research

21 pages, 10180 KiB  
Article
High Gain Improved Planar Yagi Uda Antenna for 2.4 GHz Applications and Its Influence on Human Tissues
by Claudia Constantinescu, Claudia Pacurar, Adina Giurgiuman, Calin Munteanu, Sergiu Andreica and Marian Gliga
Appl. Sci. 2023, 13(11), 6678; https://doi.org/10.3390/app13116678 - 30 May 2023
Cited by 2 | Viewed by 2348
Abstract
Considering the technological enhancements nowadays, antennas tend to be smaller in order to be easily integrated in devices. The most used antennas today in small high-tech devices close to the human body are planar antennas. In this paper, a Yagi Uda planar antenna [...] Read more.
Considering the technological enhancements nowadays, antennas tend to be smaller in order to be easily integrated in devices. The most used antennas today in small high-tech devices close to the human body are planar antennas. In this paper, a Yagi Uda planar antenna operating at a frequency of 2.4 GHz is HF analyzed and optimized by increasing its bandwidth and gain while maintaining its initial dimensions. The methods used to optimize the antenna’s operation are the use of different dielectrics, different numbers of directors, and different dimensions for directors, placing new conductor elements, all while keeping the same dimensions for its implementation on the planar device. The optimized structure of the planar Yagi Uda antenna has a 10% increase in bandwidth and a 30% increase in gain, reaching a peak value of 4.84 dBi. In our daily activities, we use devices with such antennas very often, so an analysis of the antenna’s influence on the human body is performed: the SAR, electric and magnetic field and radiation power density are determined, represented and reported to the standards in force. For the frequency considered, the SAR should be below 4 W/kg for the head/torso when the exposure is more than six minutes, which is a value exceeded by the antenna in its near vicinity. The calculated maximum electric field limit is 0.349 V/m and the maximum magnetic field value is 28.441 V/m for an exposure between 6 and 30 min values, which is also exceeded in the immediate vicinity of the antenna. The results allow us to suggest that such an antenna should be placed further from the human body, or some protection should be placed between the body and the antenna. From the radiation power density point of view for the modeled antenna, it can be said that a distance from the antenna greater than 0.5 m is considered to be safe. Full article
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11 pages, 7617 KiB  
Communication
A Low-Profile Dual-Polarized Magneto-Electric Dipole Antenna for 5G Applications
by Yulong Zhu, Qingquan Tan and Kuikui Fan
Appl. Sci. 2023, 13(1), 530; https://doi.org/10.3390/app13010530 - 30 Dec 2022
Viewed by 1720
Abstract
A low-profile dual-polarized magneto-electric dipole (MED) is presented in this communication. The low profile was achieved using meander slots on the vertical magneto dipole, reducing the antenna height to 0.15λ0, where λ0 is the wavelength of the center frequency. Relatively, [...] Read more.
A low-profile dual-polarized magneto-electric dipole (MED) is presented in this communication. The low profile was achieved using meander slots on the vertical magneto dipole, reducing the antenna height to 0.15λ0, where λ0 is the wavelength of the center frequency. Relatively, the proposed MED structure is easier to process and more stable than the traditional low-profile MED structure. The broadband performance for 5G Applications was realized based on MED structure, and the dual-polarization structure has wider coverage area and lower multipath transmission losses. Moreover, the orthogonal feeding structure provides a satisfying isolation between two ports. To verify the simulation results, a prototype of the proposed antenna was fabricated and measured. The results show that the overlapped operating frequency bandwidth with |S11| ≤ −10 dB, |S12| ≤ −20 dB was 36.8% from 3.1 GHz to 4.5 GHz, the peak gain reached 10.2 dBi, and the average gain exceeded 8.5 dBi. The measured 3 dB beamwidth with more than 44 degrees beamwidth was realized in both E-plane and H-plane. In addition, cross-polarization levels below −22 dB that covered the above frequency band were achieved. Compared with other MED antennas, in addition to broadband and high gain, the proposed antenna has the advantages of a low profile, easy processing, and low cost, which make it a competitive candidate for 5G applications. Full article
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10 pages, 4964 KiB  
Communication
A Wideband Microstrip-to-Waveguide Transition Using E-Plane Probe with Parasitic Patch for W-Band Application
by Min Han, Chengzhi Wang, Chao Liu, Shuwen Xiao, Jianguang Ma and Hui Sun
Appl. Sci. 2022, 12(23), 12162; https://doi.org/10.3390/app122312162 - 28 Nov 2022
Cited by 1 | Viewed by 1935
Abstract
The hollow metal waveguides are attractive components for millimeter-wave circuits owing to low loss. To integrate with the front-end circuit, a transition from microstrip line to waveguide is required. In this article, a microstrip-to-waveguide transition is presented in the W-band by using an [...] Read more.
The hollow metal waveguides are attractive components for millimeter-wave circuits owing to low loss. To integrate with the front-end circuit, a transition from microstrip line to waveguide is required. In this article, a microstrip-to-waveguide transition is presented in the W-band by using an E-plane probe with a parasitic patch. The probe is embedded into the waveguide along the center of the broad wall to excite the TE10 mode. A backshort-circuited waveguide with a quarter wavelength is used to obtain sufficient energy coupling and achieve good impedance matching. The additional parasitic patch can introduce a new resonance at a low frequency to enhance the working bandwidth. Hence, the proposed transition achieves wide working bandwidth and low insertion loss. For verification, a back-to-back transition is constructed and measured. The measured results indicate that the proposed transition has a wide working bandwidth covering the entire W-band. The measured reflection coefficient is below −13 dB from 70 to 110 GHz and the average insert loss is 1.1 dB. Attributed to wide working bandwidth and simple structure, the proposed transition is attractive for W-band circuit systems. Full article
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15 pages, 2098 KiB  
Article
Performance Investigation of Linearly Arranged Circular, Circular Planer, Rectangular, and Concentric Circular Antenna Arrays Using Robust NVL Techniques
by Imteaz Rahaman, Md. Shakiul Jafor, Narinderjit Singh Sawaran Singh, Md Ashraful Haque, Antar Kumar Biswas, Md Afzalur Rahman, M Azman B Zakariya, Ghulam E Mustafa Abro and Nayan Sarker
Appl. Sci. 2022, 12(22), 11481; https://doi.org/10.3390/app122211481 - 11 Nov 2022
Cited by 1 | Viewed by 1165
Abstract
In this research, linearly arranged circular antenna array (LCAA), linearly arranged circular planer antenna array (LCPAA), linearly arranged rectangular antenna array (LRAA), and linearly arranged concentric circular antenna array (LCCAA) are analyzed using robust techniques. These four antenna arrays are briefly investigated to [...] Read more.
In this research, linearly arranged circular antenna array (LCAA), linearly arranged circular planer antenna array (LCPAA), linearly arranged rectangular antenna array (LRAA), and linearly arranged concentric circular antenna array (LCCAA) are analyzed using robust techniques. These four antenna arrays are briefly investigated to evaluate their beam width performance, ability to detect a false signal, and SINR power pattern performances. Robust techniques—fixed diagonal loading (FDL), optimal diagonal loading (ODL), variable diagonal loading (VDL), and new variable loading (NVL) techniques—are applied, and the NVL technique is found to be superior and provides the best performance with the proposed LCCAA beamformer. With an SINR of 40.45 dB, 40.29 dB, 40.18 dB, and 39.99 dB for 0°, 1°, 2°, and 3° disparity angles, respectively, and output powers of −0.019 dB, −0.076 dB, and −0.171 dB for 1°, 2°, and 3° disparity angles, respectively, LCCAA beamformers using the NVL technique outperform other beamformers with different robust approaches. Full article
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10 pages, 4839 KiB  
Communication
A Wideband Folded Dipole Antenna with an Improved Cross-Polarization Level for Millimeter-Wave Applications
by Lianpeng Xue, Qiangquan Tan, Ke Cheng and Kuikui Fan
Appl. Sci. 2022, 12(21), 11291; https://doi.org/10.3390/app122111291 - 07 Nov 2022
Cited by 1 | Viewed by 2798
Abstract
A low-profile planar millimeter-wave (MMW) folded dipole antenna fed by substrate integrated waveguide (SIW) is proposed in this letter. By etching the gaps at the proper position of 1.5λ dipole, an additional resonant mode is generated. Accordingly, the working bandwidth is greatly broadened. [...] Read more.
A low-profile planar millimeter-wave (MMW) folded dipole antenna fed by substrate integrated waveguide (SIW) is proposed in this letter. By etching the gaps at the proper position of 1.5λ dipole, an additional resonant mode is generated. Accordingly, the working bandwidth is greatly broadened. In addition, by appropriately adjusting the length of the dual-side parallel strip line (DSPSL), the radiated electric fields generated by the aperture of the feeding SIW and the connecting metallic vias of the folded dipole are designed with an out-of-phase potential. Hence, the cross-polarization of the presented folded dipole antenna is improved as well. As a demonstration, a prototype is fabricated and measured. The experimental results exhibit that the proposed folded dipole has a −10 dB impedance bandwidth of 58.5% (from 30.3 GHz to 53.7 GHz), a gain of around 5 dBi with more than 120 degrees beamwidth in H-plane, and a cross-polarization levels below −15 dB, covering the working frequency band. Compared with the up-to-date planar dipole antenna, the proposed folded dipole achieves the widest working bandwidth and low cross-polarization level. The proposed antenna can be used as the terminal antenna of the MMW communication system. Full article
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9 pages, 3650 KiB  
Communication
Wideband Three-Dimensional Absorber Based on Notch-Slot Resonator with Lossy Coupled Microstrip Line
by Yufeng Yu, Dayong Gong, Guotai Xie, Qi Liu and Liang Peng
Appl. Sci. 2022, 12(21), 11082; https://doi.org/10.3390/app122111082 - 01 Nov 2022
Cited by 2 | Viewed by 839
Abstract
A wideband three-dimensional (3D) absorber based on a notch-slot resonator is proposed in this paper. A lossy coupled microstrip line was applied to eliminate the reflection band of the original lossy notch-slot resonator, resulting in a wide absorption band. A single-polarized design was [...] Read more.
A wideband three-dimensional (3D) absorber based on a notch-slot resonator is proposed in this paper. A lossy coupled microstrip line was applied to eliminate the reflection band of the original lossy notch-slot resonator, resulting in a wide absorption band. A single-polarized design was first proposed, and the operating principle was demonstrated. Then, a dual-polarized design was presented, fabricated and measured. To eliminate the undesirable resonances caused by the securing slits cut between the two adjacent unit cells, some shorting pins were introduced. The measured results show that the dual-polarized absorber exhibits an absorption band from 2.74 GHz to 11.08 GHz (120.69% fractional bandwidth), and it is also stable under the incident angles up to 40° for both TE and TM polarizations. Full article
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9 pages, 4322 KiB  
Communication
Wideband Circularly Polarized Filtering Hybrid Antenna
by Yahui Qian and Shumin Xie
Appl. Sci. 2022, 12(21), 11018; https://doi.org/10.3390/app122111018 - 31 Oct 2022
Cited by 4 | Viewed by 1280
Abstract
In this paper, a wideband circularly polarized (CP) filtering hybrid antenna is presented. The liquid dielectric resonator (DR) is excited by a microstrip-coupled cross-slot to generate CP radiation. Four inverted L-shaped strips are loaded on the ground plane to introduce an additional CP [...] Read more.
In this paper, a wideband circularly polarized (CP) filtering hybrid antenna is presented. The liquid dielectric resonator (DR) is excited by a microstrip-coupled cross-slot to generate CP radiation. Four inverted L-shaped strips are loaded on the ground plane to introduce an additional CP resonant point, then two adjacent axial ratio (AR) minima are combined to improve the bandwidth of the single-feed CP antenna. By etching a U-shaped slot and loading a C-shaped microstrip stub on the microstrip line, two tunable radiation nulls near the edges of the working band can be obtained without any extra filtering circuits. To verify the design, a filtering CP antenna is designed, fabricated, and tested. Measured results show that the antenna provides wider 3-dB AR and an impedance bandwidth of 38.8% from 1.36 to 2.02 GHz and 39.4% from 1.37 to 2.04 GHz, respectively. The realized gain of the proposed antenna is stable at about 7.8 dBi within the whole working band. A reasonable agreement between measured and simulated results is observed. Full article
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