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14 pages, 9136 KiB

Open AccessArticle

Millimeter-Wave High-Gain Dual-Polarized Flat Luneburg Lens Antenna with Reflection Cancellation

by Yan Zhang, Yinsen Luo and Ran Ji

Appl. Sci. 2023, 13(11), 6468; https://doi.org/10.3390/app13116468 - 25 May 2023

Cited by 1 | Viewed by 1726

Because of its good beam coverage and beam scanning abilities, the Luneburg lens (LL) is a promising multibeam antenna for the fifth-generation (5G) wireless communications. However, the conventional LL has a spherical formfactor, exhibiting a large volume, large weight, and curvature surface, all [...] Read more.

Because of its good beam coverage and beam scanning abilities, the Luneburg lens (LL) is a promising multibeam antenna for the fifth-generation (5G) wireless communications. However, the conventional LL has a spherical formfactor, exhibiting a large volume, large weight, and curvature surface, all of which limit the adoption of an LL in practice. To alleviate the problem, a flat LL is proposed, with transformation optics to convert the conventional spherical structure into a flat one. However, a high permittivity distribution is usually required in a transformed flat LL, causing of server reflections, which further degenerates the performance of the LL in terms of both gain and efficiency. In this article, a millimeter-wave dual-polarized flat Luneburg lens antenna (FLLA) is proposed following the transformation of optics, and implemented using multilayer PCBs, where a reflection cancellation method is introduced to optimize the multilayer structure to improve its gain and efficiency. The designed FLLA is exemplified in the Ka-band and fed using a dual-polarized patch antenna. The measured results show that the designed FLLA has an impedance bandwidth (|S₁₁| ≤ −10 dB) of 27.5–32.6 GHz, a gain of 16.8–18.8 dBi over the operating band, and a beam scanning range up to ±25°/±24° with a gain loss of 1.72 dB/1.7 dB in either E- or H-plane, respectively. Full article

(This article belongs to the Special Issue Emerging Antenna and Radiofrequency Technologies for 5G and 6G Wireless Communications)

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16 pages, 8357 KiB

Open AccessArticle

Highly Compact 4 × 4 Flower-Shaped MIMO Antenna for Wideband Communications

by Wael A. E. Ali and Rowan A. Ibrahim

Appl. Sci. 2023, 13(6), 3532; https://doi.org/10.3390/app13063532 - 10 Mar 2023

Cited by 3 | Viewed by 1304

Abstract

This paper introduces an MIMO antenna with a highly compact size of 30 mm width and 30 mm length. Four symmetrical MIMO antenna radiators are utilized with decoupling stubs in the top and bottom planes of the substrate to improve the isolation level. [...] Read more.

This paper introduces an MIMO antenna with a highly compact size of 30 mm width and 30 mm length. Four symmetrical MIMO antenna radiators are utilized with decoupling stubs in the top and bottom planes of the substrate to improve the isolation level. The simulated and measured outcomes are validated to investigate the impact of the suggested MIMO antenna for wideband applications. The suggested MIMO antenna has an impedance matching less than −10 dB from 5.8 GHz up to 11 GHz, and the isolation between the four radiators exceeds 20 dB over this band. Moreover, the antenna provides an envelope correlation coefficient not exceeding 0.004, a diversity gain above 9.97 dB, and a mean effective gain of ≤−3 dB over the achieved frequency range. The suggested MIMO antenna exhibits a nearly omnidirectional radiation pattern in one plane and a bi-directional radiation pattern in the other plane with an acceptable average value of the realized gain (4 dBi) over the achieved frequency band. A comparison with the state-of-the-art is tabulated to show the distinct performance of the suggested MIMO antenna for wideband applications. Full article

(This article belongs to the Special Issue Emerging Antenna and Radiofrequency Technologies for 5G and 6G Wireless Communications)

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13 pages, 362 KiB

Open AccessArticle

Intelligent-Reflecting-Surface-Assisted Multicasting with Joint Beamforming and Phase Adjustment

by Duckdong Hwang, Sung Sik Nam, Janghoon Yang and Hyoung-Kyu Song

Appl. Sci. 2023, 13(1), 386; https://doi.org/10.3390/app13010386 - 28 Dec 2022

Viewed by 1155

Abstract

In this paper, a set of transmission schemes are proposed for the delivery of multicast (MC) signals, in which an intelligent reflecting surface (IRS) assists the transmission from an access point (AP) to a set of multicast users. It is known that the [...] Read more.

In this paper, a set of transmission schemes are proposed for the delivery of multicast (MC) signals, in which an intelligent reflecting surface (IRS) assists the transmission from an access point (AP) to a set of multicast users. It is known that the large number of IRS reflecting elements have the potential to improve the transmission efficiency by forming an artificial signal path with strong channel gain. However, the joint optimization of the AP beamformer and the phases of the IRS reflecting elements is challenging due to the non-convex nature of the phase elements as well as the high computational complexity required for a large number of elements. A set composed of two AP beamformer schemes and a set with two IRS phase adjustment algorithms are proposed, which are sub-optimal but less computationally demanding. A semi-definite relaxation (SDR)-based scheme is considered along with a least squares (LS) based one for the AP beamformer design. For the IRS phase adjustment, an LS based optimization and a grouping method for the phase elements are suggested. From these two sets, four combinations of overall optimization can be built, and their performances can be compared with their merits and weaknesses revealed. The signal-to-interference-plus-noise power ratio (SINR) performance results are verified in various parameter conditions by simulation. Full article

(This article belongs to the Special Issue Emerging Antenna and Radiofrequency Technologies for 5G and 6G Wireless Communications)

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13 pages, 4979 KiB

Open AccessArticle

A Maximum Efficiency-86% Hybrid Power Modulator for 5G New Radio(NR) Applications

by Xingli Cui, Xin Qiu, Yongqing Leng, Xiaotian Liu and Tianyu Wu

Appl. Sci. 2022, 12(23), 12041; https://doi.org/10.3390/app122312041 - 25 Nov 2022

Viewed by 1530

Abstract

A hybrid power modulator is presented for the radio frequency (RF) power amplifiers of 5th generation mobile communication technology (5G) new radio (NR) applications. A hybrid power modulator utilizing a two-level switching converter and a broadband and high-efficiency linear amplifier is presented. A [...] Read more.

A hybrid power modulator is presented for the radio frequency (RF) power amplifiers of 5th generation mobile communication technology (5G) new radio (NR) applications. A hybrid power modulator utilizing a two-level switching converter and a broadband and high-efficiency linear amplifier is presented. A further improvement in the efficiency of the circuit is achieved by using an optimized supply voltage of the two-level switching converters of 4.5 V. In this way, the overall efficiency is improved by more than 5% compared to using a 5 V supply voltage. The linear amplifier consists of four stages. In order to improve bandwidth and circuit stability, a compensation circuit is added to the linear amplifier that eliminates the poles of the main amplifier by introducing additional zeros, indirectly pushing the pole distribution out of the bandwidth. Using this approach, the linear amplifier achieves a 3-dB bandwidth of 180 MHz and an efficiency of 51%. The hybrid power modulator achieves a maximum output power of 2.4 W and an efficiency of 86% when tracking a 100 MHz 5G-NR signal under a 4 Ω load in a 180 nm CMOS package. Full article

(This article belongs to the Special Issue Emerging Antenna and Radiofrequency Technologies for 5G and 6G Wireless Communications)

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14 pages, 4378 KiB

Open AccessArticle

Three-Level Hybrid Envelope Tracking Supply Modulator with High-Bandwidth Wide-Output-Swing

by Ke Yang, Yongqing Leng, Chengying Chen, Xin Qiu, Xingli Cui, Bo Xu and Ming Hui

Appl. Sci. 2022, 12(22), 11352; https://doi.org/10.3390/app122211352 - 9 Nov 2022

Viewed by 1716

Abstract

Envelope tracking is a dynamic supply modulation technique, which is mainly used to improve the efficiency of radio frequency power amplifier. For 5G NR mobile devices, this paper presents an envelope tracking supply modulator which is composed of a three-level switching converter and [...] Read more.

Envelope tracking is a dynamic supply modulation technique, which is mainly used to improve the efficiency of radio frequency power amplifier. For 5G NR mobile devices, this paper presents an envelope tracking supply modulator which is composed of a three-level switching converter and linear amplifier (LA) in parallel. The hysteresis control method is adopted in the supply modulator to improve the bandwidth of the switching converter and the loop response speed. At the same time, a rail-to-rail input-output class AB linear amplifier is designed to achieve a wide output swing and a super source follower is proposed to reduce the output impedance of LA. Designed with the 180 nm CMOS technology, the supply modulator operated at 5G NR 100 MHz envelope signal. The output power of the modulator reaches 1.5 W for a 6 Ω load resistor and the output swing is 4.3 V at 5.0 V supply, and the maximum efficiency reaches 85%. Full article

(This article belongs to the Special Issue Emerging Antenna and Radiofrequency Technologies for 5G and 6G Wireless Communications)

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13 pages, 6416 KiB

Open AccessArticle

Design of 2–16 GHz Non-Uniform Distributed GaN HEMT MMIC Power Amplifier with Harmonic Suppression Network

by Tongyao Luan, Yongqing Leng, Xin Qiu, Xingli Cui, Aizhen Hu, Bo Xu and Yatao Peng

Appl. Sci. 2022, 12(21), 11077; https://doi.org/10.3390/app122111077 - 1 Nov 2022

Viewed by 2332

Abstract

In this paper, an ultra-wideband (UWB) power amplifier (PA) on a 0.25 μm gallium-nitride (GaN) on silicon carbide (SiC) high-electron-mobility transistor (HEMT) process, operating in Ku-band, is presented. The broadband PA design is based on the four-stage non-uniform distributed amplifier structure. In order [...] Read more.

In this paper, an ultra-wideband (UWB) power amplifier (PA) on a 0.25 μm gallium-nitride (GaN) on silicon carbide (SiC) high-electron-mobility transistor (HEMT) process, operating in Ku-band, is presented. The broadband PA design is based on the four-stage non-uniform distributed amplifier structure. In order to improve the efficiency of the PA, a harmonic suppression network is added at the output of the drain artificial transmission line. At the same time, a capacitor is connected in series at the input of the gate, which is used to compensate for the phase offset of the gate and increase the cut-off frequency of the PA. The final gate width of the first stage is 0.56 μm, and the other three-stage gate widths are all 0.32 μm. Over the frequency range of 2–16 GHz, the simulated results of this NDPA exhibit a power-added efficiency (PAE) of 16.6–27%, a saturated continuous wave (CW) output power of 35–37 dBm, a small signal gain of 9.1–11.6 dB, and output return losses of 5–15 dB. Full article

(This article belongs to the Special Issue Emerging Antenna and Radiofrequency Technologies for 5G and 6G Wireless Communications)

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11 pages, 5344 KiB

Open AccessArticle

A 7–13 GHz 10 W High-Efficiency MMIC Power Amplifier in 0.25 µm GaN HEMT Process

by Aizhen Hu, Yongqing Leng, Xin Qiu, Tongyao Luan and Yatao Peng

Appl. Sci. 2022, 12(21), 10872; https://doi.org/10.3390/app122110872 - 26 Oct 2022

Cited by 1 | Viewed by 2019

Abstract

With the increase in applications of the millimeter wave spectrum for phased array radar systems, mobile 7–13 communication systems, and satellite systems, the demand for a wideband, high-efficiency, high-power monolithic microwave integrated circuit (MMIC) power amplifier (PA) is increasing. In this paper, a [...] Read more.

With the increase in applications of the millimeter wave spectrum for phased array radar systems, mobile 7–13 communication systems, and satellite systems, the demand for a wideband, high-efficiency, high-power monolithic microwave integrated circuit (MMIC) power amplifier (PA) is increasing. In this paper, a 7–13 GHz 10 W high-efficiency MMIC PA is designed. This amplifier consists of a two-stage circuit structure with two high electron mobility transistor (HEMT) cells for the driver stage and four HEMT cells for the power stage. To ensure high efficiency and a certain output power (

P_{o u t}

), both the driver–stage and power–stage transistors use a deep Class–AB bias. At the same time, in order to further improve the efficiency, low-loss and second–harmonic tuning techniques are used in the output and inter-stage matching networks, respectively. Finally, the electromagnetic simulation results show that within a frequency of 7–13 GHz, the amplifier achieves an average saturated continuous wave (CW)

P_{o u t}

of 40 dBm, a small signal gain of 14.5–15.5 dB, a power-added efficiency (PAE) of 30–46%, and the input and output return loss are better than 5 dB and 8 dB, respectively. Full article

(This article belongs to the Special Issue Emerging Antenna and Radiofrequency Technologies for 5G and 6G Wireless Communications)

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11 pages, 4789 KiB

Open AccessCommunication

T-Type Vertical Wall for Decoupling and Pattern Correction of Patch Antenna

by Yiying Wang, Shengfei Zhang, Bo Wang, Dun Lan, Xinhua Yu, Jinjun Mo and Ahmed A. Kishk

Appl. Sci. 2022, 12(21), 10732; https://doi.org/10.3390/app122110732 - 23 Oct 2022

Cited by 3 | Viewed by 1774

Abstract

The requirements of 5G/6G promote progress in the miniaturization of the antenna array, which promotes the development of a closely spaced decoupling technique. However, the present techniques face the common problem of beam tilt if the spacing is close. Thus, a pattern-corrected, closely-spaced [...] Read more.

The requirements of 5G/6G promote progress in the miniaturization of the antenna array, which promotes the development of a closely spaced decoupling technique. However, the present techniques face the common problem of beam tilt if the spacing is close. Thus, a pattern-corrected, closely-spaced technique is proposed in this paper for the two patch antennas with the λ₀/20 edge-to-edge distance of the H-plane. The corresponding structure, which is inserted at the center of the spacing, consists of a vertical wall with a single substrate and two symmetrical T-type metals, and a slot at the center is reserved to adequately accommodate the vertical wall. The vertical strip at the other end of the T-type metal is connected to the ground of the patch antenna, while the parallel strip is placed exactly above the patch substrate. After an exact analysis, a prototype was fabricated and measured, and the results showed that the measurements agreed well with those of the simulations, the decoupling coefficients in the 5.8 GHz band were below −20 dB, and the measured radiation pattern at 5.81 GHz was corrected to the broadside from 28° and the maximum realized gain was 5.30 dB. Full article

(This article belongs to the Special Issue Emerging Antenna and Radiofrequency Technologies for 5G and 6G Wireless Communications)

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9 pages, 2768 KiB

Open AccessCommunication

Analysis of Wideband Scattering from Antenna Based on RFGG-FG-FFT with Cube Polynomial Inter/Extrapolation Method

by Weibin Kong, Yongtao Zheng, Yubin Song, Zhongqing Fang, Xiaofang Yang and Haonan Zhang

Appl. Sci. 2022, 12(20), 10298; https://doi.org/10.3390/app122010298 - 13 Oct 2022

Cited by 1 | Viewed by 1114

Abstract

This paper presents an efficient real-coefficient fitting both Green’s function and its gradient with Fast Fourier Transform (RFGG-FG-FFT) with cube polynomial inter/extrapolation method (CPIE), which is established for the analysis of scattering from antenna over a wide frequency. To improve the computation efficiency, [...] Read more.

This paper presents an efficient real-coefficient fitting both Green’s function and its gradient with Fast Fourier Transform (RFGG-FG-FFT) with cube polynomial inter/extrapolation method (CPIE), which is established for the analysis of scattering from antenna over a wide frequency. To improve the computation efficiency, the CPIE is utilized. In order to reduce memory requirements and accelerate matrix vector multiplication, the RFGG-FG-FFT is adopted. The accuracy, correctness and efficiency of the new method are researched on some examples. Compared with the direct method, the examples show that the new method is superior in broadband without loss of accuracy. Full article

(This article belongs to the Special Issue Emerging Antenna and Radiofrequency Technologies for 5G and 6G Wireless Communications)

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11 pages, 31940 KiB

Open AccessCommunication

A Compact Broadband Planar Inverted-F Antenna with Dual-Resonant Modes

by Zhengya Qi, Xinhao Ding, Wenwen Yang and Jianxin Chen

Appl. Sci. 2022, 12(17), 8915; https://doi.org/10.3390/app12178915 - 5 Sep 2022

Cited by 3 | Viewed by 2317

Abstract

In this paper, a compact broadband planar inverted-F antenna (PIFA) with dual-resonant modes (TM_1/2,₂ and TM_3/2,₀) is proposed for 5G applications. By loading a pair of horizontal slots on the patch, the TM_3/2,0 mode can be shifted [...] Read more.

In this paper, a compact broadband planar inverted-F antenna (PIFA) with dual-resonant modes (TM_1/2,₂ and TM_3/2,₀) is proposed for 5G applications. By loading a pair of horizontal slots on the patch, the TM_3/2,0 mode can be shifted downward and combined with the TM_1/2,₂ mode, leading to a dual-mode operation. Meanwhile, another pair of slots, which are orthogonal to the previous pair, is introduced to improve the impedance matching of the antenna. Moreover, the substrate with a high dielectric constant is used in this design to achieve a compact antenna size. In order to verify the principle and the design method, an antenna prototype was fabricated and measured. Experimental results show that the PIFA has a good performance with a −10 dB impedance bandwidth of 14.5% (3.17–3.67 GHz), a peak gain of 6.23 dBi, a low cross-polarization level of −17.3 dB, and a compact size of 0.45 × 0.26 × 0.03 λ₀₁³ (λ₀₁ is the free-space wavelength at 3.5 GHz). The antenna is predicted to be suitable for 5G terminal applications. Full article

(This article belongs to the Special Issue Emerging Antenna and Radiofrequency Technologies for 5G and 6G Wireless Communications)

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