Micromachines

Editorial

6 pages, 203 KiB

Open AccessEditorial

Editorial for the Special Issue on the New Trends in Microwave/Millimeter Antennas/Filters: From Fundamental Research to Applications

by Ahmed A. Ibrahim and Syed Muzahir Abbas

Micromachines 2023, 14(11), 2019; https://doi.org/10.3390/mi14112019 - 30 Oct 2023

Viewed by 1038

Abstract

The rapid growth of wireless communication systems has led to high demand for the design of microwave/millimeter components with multiband characteristics, high performance, and ease of integration with other devices [...] Full article

(This article belongs to the Special Issue New Trends in Microwave/Millimeter Antennas/Filters: From Fundamental Research to Applications)

Research

Jump to: Editorial

12 pages, 4428 KiB

Open AccessArticle

Designing a Compact Filtering Quasi-Yagi Antenna with Multiple Radiation Nulls Using Embedded Resistor-Loaded Arms

by Lipeng Zhai, Yi Guo, Zongming Xu, Xuefeng Zhang, Yanyun Chen and Jin Shi

Micromachines 2023, 14(7), 1445; https://doi.org/10.3390/mi14071445 - 19 Jul 2023

Cited by 3 | Viewed by 1569

Abstract

In this paper, a compact quasi-Yagi antenna with embedded resistor-loaded arms is proposed to obtain a filtering response with four radiation nulls. The embedded resistor-loaded arms achieve two additional radiation nulls caused by reverse currents and absorb the unwanted out-of-band resonant points brought [...] Read more.

In this paper, a compact quasi-Yagi antenna with embedded resistor-loaded arms is proposed to obtain a filtering response with four radiation nulls. The embedded resistor-loaded arms achieve two additional radiation nulls caused by reverse currents and absorb the unwanted out-of-band resonant points brought by themselves. The director close to the driver provides a resonant point and a radiation null caused by opposite currents between the driver and the director. Compared with other filtering quasi-Yagi antennas, the proposed one can achieve a filtering response with a compact size along the endfire direction. For demonstration, a balun-integrated prototype covering the 5G band N78 (3.3–3.8 GHz) is designed with the size along the endfire direction (without ground) of 0.13 λ₀ (λ₀ is the wavelength in the free space at center frequency), and the measured results show a 10 dB impedance-matching bandwidth of 22.9% (3.21–4.04 GHz), four radiation nulls, and a peak gain of 4.73 dBi. Full article

(This article belongs to the Special Issue New Trends in Microwave/Millimeter Antennas/Filters: From Fundamental Research to Applications)

► Show Figures

Figure 1

13 pages, 12509 KiB

Open AccessArticle

Wide Dual-Band Circularly Polarized Diecletric Resonator: Innovative Integration of a Single Hybrid Feed and Thin Grounded Metasurface

by Arslan Kiyani, Mohsen Asadnia, Syed Muzahir Abbas, Karu P. Esselle and Abdelhady Mahmoud

Micromachines 2023, 14(7), 1432; https://doi.org/10.3390/mi14071432 - 16 Jul 2023

Cited by 2 | Viewed by 1401

Abstract

This article presents an application of a grounded substrate-based metasurface for hosting dielectric resonators (DRs), enabling a wide dual-band circularly polarized (CP) operation. The antenna structure comprises centrally positioned rectangular DRs, one above the other, along with a 7 × 7 square-slotted metasurface. [...] Read more.

This article presents an application of a grounded substrate-based metasurface for hosting dielectric resonators (DRs), enabling a wide dual-band circularly polarized (CP) operation. The antenna structure comprises centrally positioned rectangular DRs, one above the other, along with a 7 × 7 square-slotted metasurface. The metasurface and DRs are hosted above a grounded substrate, which is fed through a single coaxial feed placed at a specific angle, employing a modified upper probe of the coaxial feed. The proposed hybrid technique utilizes the combined benefits of the feed angle and a well-matched metasurface, resulting in performance improvement. Notably, a measured impedance bandwidth of 88.1% for

| S_{11} |

is achieved within the frequency range of 4.0 GHz to 10.3 GHz. Furthermore, the antenna design exhibits two overlapping measured 3-dB axial ratio (AR) bandwidths: 23.62% from 4.25 GHz to 5.4 GHz and 5.12% from 7.6 GHz to 8 GHz. The peak gain of the antenna is measured at 8.4 dBic. Consequently, this innovative single-feed antenna design, characterized by its compact profile, holds significant potential for realizing multi-band operations. Furthermore, the developed antenna is well-suited for deployment in indoor radio links and INSAT applications. Full article

(This article belongs to the Special Issue New Trends in Microwave/Millimeter Antennas/Filters: From Fundamental Research to Applications)

► Show Figures

Figure 1

24 pages, 13244 KiB

Open AccessArticle

Investigation of Parallel and Orthogonal MIMO Antennas with Two-Notched Structures for Ultra-Wideband Application

by Liang Wang, Ziwei Li and Hongxing Zheng

Micromachines 2023, 14(7), 1406; https://doi.org/10.3390/mi14071406 - 11 Jul 2023

Cited by 1 | Viewed by 1433

Abstract

Ultra-wideband (UWB) technology is widely used in many communication scenarios. However, narrowband systems can easily interfere with the UWB system, which generates multipath fading. In order to solve these interferences and meet the design requirements of high isolation of multiple-input multiple-output (MIMO) antennas, [...] Read more.

Ultra-wideband (UWB) technology is widely used in many communication scenarios. However, narrowband systems can easily interfere with the UWB system, which generates multipath fading. In order to solve these interferences and meet the design requirements of high isolation of multiple-input multiple-output (MIMO) antennas, two MIMO antennas with double-notch structures are designed. Firstly, two U-shaped slots are etched on the radiating patch and feeder to achieve notch characteristics in WiMAX and ITU bands. Using this antenna element, a two-element antenna is put symmetrically in parallel, and two rectangular branches are loaded to improve the isolation. The size is 0.57λ × 0.32λ × 0.013λ (at 2.5 GHz). Then, a four-element antenna is designed to meet the requirements for another application; here, each element is placed orthogonally to each other, and the isolation is improved through loading a cross-shaped branch in the middle of these elements. The size is 0.57λ × 0.57λ × 0.013λ. Both antenna samples are tested to verify the design. Measurement results show that the working bandwidth is 2.45–14.88 GHz and 2.14–14.95 GHz, the isolation is greater than 17 and 20 dB, and the peak gain is 5.7 and 5.9 dBi for the two- and four-element MIMO antenna, respectively. Compared to the references, the designed antennas have a wider bandwidth and a higher gain and radiation efficiency. They are well-suited for diverse wireless applications. Full article

(This article belongs to the Special Issue New Trends in Microwave/Millimeter Antennas/Filters: From Fundamental Research to Applications)

► Show Figures

Figure 1

8 pages, 3357 KiB

Open AccessCommunication

A Bandpass Filter Realized by Using Pixel Structure and Genetic Algorithm Optimization

by Yangyang He, Yi-Feng Cheng and Jiang Luo

Micromachines 2023, 14(7), 1389; https://doi.org/10.3390/mi14071389 - 7 Jul 2023

Viewed by 1186

Abstract

This paper presents a flexible method for designing a bandpass filter (BPF) using pixel structure and genetic algorithm (GA) optimization. The pixel structure is made up of a grid of metallic microstrip stubs, and the GA is utilized to determine the connections between [...] Read more.

This paper presents a flexible method for designing a bandpass filter (BPF) using pixel structure and genetic algorithm (GA) optimization. The pixel structure is made up of a grid of metallic microstrip stubs, and the GA is utilized to determine the connections between these stubs. The pixel structure enables the construction of step impedance and shunt branches, which are used to design a traditional BPF. To enhance the design freedom, one side of the discrete grids is connected to the ground via metallic holes. For verification, a BPF was designed, simulated, and measured. The experimental results showed that the 10 dB return loss bandwidth ranges from 1.1 to 1.9 GHz and the insertion loss is approximately 2.5 dB. There is good agreement between the calculation, EM simulation, and measurement results. The proposed GA-based design method offers significant advantages in terms of one-time EM simulation, feasibility, and labor time savings, making it more convenient than the traditional design method. Full article

(This article belongs to the Special Issue New Trends in Microwave/Millimeter Antennas/Filters: From Fundamental Research to Applications)

► Show Figures

Figure 1

14 pages, 5934 KiB

Open AccessArticle

Improved Stable Read Range of the RFID Tag Using Slot Apertures and Capacitive Gaps for Outdoor Localization Applications

by Redouane Jouali, Hassan Ouahmane, Jalal Khan, Maryam Liaqat, Azize Bhaij, Sarosh Ahmad, Abderrahim Haddad and Mohssin Aoutoul

Micromachines 2023, 14(7), 1364; https://doi.org/10.3390/mi14071364 - 30 Jun 2023

Cited by 3 | Viewed by 1464

Abstract

This paper proposes a small-size UHF RFID tag antenna, which was designed to function in the frequency interval of 860–960 MHz, with a large-read range of up to 17 m. In this work, the effects of capacitive slots and gaps on the impedance [...] Read more.

This paper proposes a small-size UHF RFID tag antenna, which was designed to function in the frequency interval of 860–960 MHz, with a large-read range of up to 17 m. In this work, the effects of capacitive slots and gaps on the impedance matching between conventional industrial chips and a designed RFID antenna was investigated. Simulated and measured results provided a clear indication that these two techniques can efficiently improve the return loss parameter and the antenna impedance matching behavior at the UHF band. Three-dimensional electromagnetic (EM) simulations results further proved that a better impedance matching between an industrial chip and a proposed RFID antenna occurs at 870 MHz, where the estimated input antenna impedance was about Z_a = 16 + j184 (Ω), and the calculated read range reached a value of up to 17 m with a measured return loss value of –14 dB. The proposed RFID antenna can almost maintain the same read range value over a 180 degree angle variations on the horizontal plane owing to its omnidirectional radiation pattern. The fabrication and test stages of the antenna prototype were scheduled to validate the simulated characteristics. Experimental results confirmed the performances of our proposed RFID tag antenna and proved its potential ability for localization applications. EM simulations have been performed using the well-known commercial EM software simulator CST MWS. Full article

(This article belongs to the Special Issue New Trends in Microwave/Millimeter Antennas/Filters: From Fundamental Research to Applications)

► Show Figures

Figure 1

18 pages, 21352 KiB

Open AccessArticle

Ultra-Wideband and High-Gain Vivaldi Antenna with Artificial Electromagnetic Materials

by Ruiyue Hu, Feng Zhang, Shengbo Ye and Guangyou Fang

Micromachines 2023, 14(7), 1329; https://doi.org/10.3390/mi14071329 - 29 Jun 2023

Cited by 6 | Viewed by 2840

Abstract

An ultra-wideband and high-gain Vivaldi antenna with artificial electromagnetic material, suitable for ground-penetrating radar (GPR) systems, is proposed. Directors loaded inside the antenna gradient slot direct electromagnetic waves by inducing current to improve gain. The artificial electromagnetic material, also called metamaterial, is composed [...] Read more.

An ultra-wideband and high-gain Vivaldi antenna with artificial electromagnetic material, suitable for ground-penetrating radar (GPR) systems, is proposed. Directors loaded inside the antenna gradient slot direct electromagnetic waves by inducing current to improve gain. The artificial electromagnetic material, also called metamaterial, is composed of multiple “H”-shaped units arranged in a certain regular pattern, loaded at the antenna aperture. The artificial electromagnetic units affect the antenna radiation waves by changing the refractive index to improve radiation directivity. The four Vivaldi units are arranged into a horn-shaped array, and each two units are orthogonally fed to realize dual polarization. Experimental results demonstrate that the antenna has good impedance matching of

S_{11} \leq - 10

dB in 0.9–4 GHz, and the maximum realized gain can reach 15.2 dBi. Full article

(This article belongs to the Special Issue New Trends in Microwave/Millimeter Antennas/Filters: From Fundamental Research to Applications)

► Show Figures

Figure 1

14 pages, 7295 KiB

Open AccessArticle

A 12-Port MIMO Antenna System for 5G/WLAN Applications

by Wenshi You, Zhonggen Wang, Wenyan Nie and Weidong Mu

Micromachines 2023, 14(6), 1196; https://doi.org/10.3390/mi14061196 - 5 Jun 2023

Cited by 1 | Viewed by 1933

Abstract

In this paper, a 12-port MIMO antenna system for 5G/WLAN applications is proposed. The proposed antenna system consists of two types of antenna modules: an L-shaped antenna module covering the C-band (3.4–3.6 GHz) for 5G mobile applications and a folded monopole module for [...] Read more.

In this paper, a 12-port MIMO antenna system for 5G/WLAN applications is proposed. The proposed antenna system consists of two types of antenna modules: an L-shaped antenna module covering the C-band (3.4–3.6 GHz) for 5G mobile applications and a folded monopole module for the 5G/WLAN mobile application band (4.5–5.9 GHz). Each two antennas form a pair, six pairs in total, forming a 12 × 12 MIMO antenna array, and the elements between the antenna pairs can achieve an isolation of 11 dB or more without additional decoupling structures. Experimental results show that the antenna can cover the 3.3–3.6 GHz and 4.5–5.9 GHz bands with an overall efficiency greater than 75% and an envelope correlation coefficient less than 0.04. Finally, the one-hand holding mode and two-hand holding mode are discussed to demonstrate their stability in practical applications, and the results show that they still exhibit good radiation and MIMO performance when operating in both modes. Full article

(This article belongs to the Special Issue New Trends in Microwave/Millimeter Antennas/Filters: From Fundamental Research to Applications)

► Show Figures

Figure 1

16 pages, 9344 KiB

Open AccessArticle

A Compact MIMO Multiband Antenna for 5G/WLAN/WIFI-6 Devices

by Ayyaz Ali, Mehr E Munir, Mohamed Marey, Hala Mostafa, Zahriladha Zakaria, Ahmed Jamal Abdullah Al-Gburi and Farooq Ahmed Bhatti

Micromachines 2023, 14(6), 1153; https://doi.org/10.3390/mi14061153 - 30 May 2023

Cited by 17 | Viewed by 2784

Abstract

This research work presents a compact design of a Multiple-Input Multiple-Output (MIMO) multiband antenna along with high-isolation characteristics. The presented antenna was designed for 3.50 GHz, 5.50 GHz, and 6.50 GHz frequencies for 5G cellular, 5G WiFi, and WiFi-6, respectively. The fabrication of [...] Read more.

This research work presents a compact design of a Multiple-Input Multiple-Output (MIMO) multiband antenna along with high-isolation characteristics. The presented antenna was designed for 3.50 GHz, 5.50 GHz, and 6.50 GHz frequencies for 5G cellular, 5G WiFi, and WiFi-6, respectively. The fabrication of the aforementioned design was undertaken using FR-4 (1.6 mm thickness) substrate material with a loss tangent and relative permittivity of about 0.025 and 4.30, respectively. The two-element MIMO multiband antenna was miniaturized to 16 × 28 × 1.6 mm³, making it desirable for devices operating in 5G bands. High isolation (>15 dB) was attained with thorough testing without employing a decoupling scheme in the design. Laboratory measurements resulted in a peak gain of 3.49 dBi and an efficiency of around 80% in the entire operating band. The evaluation of the presented MIMO multiband antenna was carried out in terms of the envelope correlation coefficient (ECC), diversity gain (DG), total active reflection coefficient (TARC), and Channel Capacity Loss (CCL). The measured ECC was less than 0.04, and the DG was well above 9.50. The observed TARC was also lower than −10 dB, and the CCL was below 0.4 bits/s/Hz in the entire operating band. The presented MIMO multiband antenna was analyzed and simulated using CST Studio Suite 2020. Full article

(This article belongs to the Special Issue New Trends in Microwave/Millimeter Antennas/Filters: From Fundamental Research to Applications)

► Show Figures

Figure 1

13 pages, 4961 KiB

Open AccessArticle

A Compact-Size Multiple-Band Planar Inverted L-C Implantable Antenna Used for Biomedical Applications

by Sanaa Salama, D. Zyoud and A. Abuelhaija

Micromachines 2023, 14(5), 1021; https://doi.org/10.3390/mi14051021 - 10 May 2023

Cited by 2 | Viewed by 1588

Abstract

In this paper, a compact-size multiple-band planar inverted L-C implantable antenna is proposed. The compact antenna has a size of 20 mm × 12 mm × 2.2 mm and consists of planar inverted C-shaped and L-shaped radiating patches. The designed antenna is employed [...] Read more.

In this paper, a compact-size multiple-band planar inverted L-C implantable antenna is proposed. The compact antenna has a size of 20 mm × 12 mm × 2.2 mm and consists of planar inverted C-shaped and L-shaped radiating patches. The designed antenna is employed on the RO3010 substrate (ε_r = 10.2, tanδ = 0.0023, and thickness = 2 mm). An alumina layer with a thickness of 0.177 mm (ε_r = 9.4 and tanδ = 0.006) is used as the superstrate. The designed antenna operates at triple-frequency bands with a return loss of −46 dB at 402.5 MHz, −33.55 dB at 2.45 GHz, and −41.4 dB at 2.95 GHz, and provides a size reduction of 51% compared with the conventional dual-band planar inverted F-L implant antenna designed in our previous study. In addition, the SAR values are within the safety limits with a maximum allowable input power (8.43 mW (1 g) and 47.5 mW (10 g) at 402.5 MHz; 12.85 mW (1 g) and 47.8 mW (10 g) at 2.45 GHz; and 11 mW (1 g) and 50.5 mW (10 g) at 2.95 GHz). The proposed antenna operates at low power levels and supports an energy-efficient solution. The simulated gain values are −29.7 dB, −3.1 dB, and −7.3 dB, respectively. The suggested antenna is fabricated and the return loss is measured. Our findings are then compared with the simulated results. Full article

(This article belongs to the Special Issue New Trends in Microwave/Millimeter Antennas/Filters: From Fundamental Research to Applications)

► Show Figures

Figure 1

12 pages, 5011 KiB

Open AccessArticle

A Wideband GRIN Dielectric Lens Antenna for 5G Applications

by Khaled Aljaloud, Yosef T. Aladadi, Majeed A. S. Alkanhal, Wazie M. Abdulkawi and Rifaqat Hussain

Micromachines 2023, 14(5), 997; https://doi.org/10.3390/mi14050997 - 3 May 2023

Cited by 3 | Viewed by 2280

Abstract

This paper proposes a graded effective refractive indexes (GRIN) dielectric lens for 5G applications. The inhomogeneous holes in the dielectric plate are perforated to provide GRIN in the proposed lens. The constructed lens employs a collection of slabs that correspond to the specified [...] Read more.

This paper proposes a graded effective refractive indexes (GRIN) dielectric lens for 5G applications. The inhomogeneous holes in the dielectric plate are perforated to provide GRIN in the proposed lens. The constructed lens employs a collection of slabs that correspond to the specified graded effective refractive index. The thickness and the whole lens dimensions are optimized based on designing a compact lens with optimum lens antenna performance (impedance matching bandwidth, gain, 3 dB beamwidth, and sidelobe level). A wideband (WB) microstrip patch antenna is designed to be operated over the entire band of interest from 26 GHz to 30.5 GHz. For the 5G mm-wave band of operation, the behavior of the proposed lens along with a microstrip patch antenna is analyzed at 28 GHz for various performance parameters, including impedance matching bandwidth, 3 dB beamwidth, maximum gain, and sidelobe level. It has been observed that the antenna exhibits good performance over the entire band of interest in terms of gain, 3 dB beamwidth, and sidelobe level. The numerical simulation results are validated using two different simulation solvers. The proposed unique and innovative configuration is well-suited for 5G high gain antenna solutions with a low-cost and lightweight antenna structure. Full article

(This article belongs to the Special Issue New Trends in Microwave/Millimeter Antennas/Filters: From Fundamental Research to Applications)

► Show Figures

Figure 1

10 pages, 7105 KiB

Open AccessArticle

A Multi-Frequency Omnidirectional Antenna Based on a Ring-Shaped Structure

by Honglei Guo, Yu Chen, Qiannan Wu, Jianyang Wang, Yu He, Yonghong Cao and Mengwei Li

Micromachines 2023, 14(5), 994; https://doi.org/10.3390/mi14050994 - 3 May 2023

Viewed by 2250

Abstract

A multi-frequency microstrip antenna loaded with a ring-like structure has been proposed. The radiating patch on the antenna surface consists of three split-ring resonator structures, and the ground plate consists of a bottom metal strip and three ring-shaped metals with regular cuts to [...] Read more.

A multi-frequency microstrip antenna loaded with a ring-like structure has been proposed. The radiating patch on the antenna surface consists of three split-ring resonator structures, and the ground plate consists of a bottom metal strip and three ring-shaped metals with regular cuts to form a defective ground structure. The proposed antenna works in six different frequency bands covering 1.10, 1.33, 1.63, 1.97, 2.08, and 2.69 GHz and works entirely when connected to 5G NR (FR1, 0.45–3 GHz), 4GLTE (1.6265–1.6605 GHz), Personal Communication System (1.85–1.99 GHz), Universal Mobile Telecommunications System (1.92–2.176 GHz), WiMAX (2.5–2.69 GHz), and other communications frequency bands. Moreover, such antennas also have stable omnidirectional radiation properties across different operating frequency bands. This antenna meets the needs of portable multi-frequency mobile devices and provides a theoretical approach for the development of multi-frequency antennas. Full article

(This article belongs to the Special Issue New Trends in Microwave/Millimeter Antennas/Filters: From Fundamental Research to Applications)

► Show Figures

Figure 1

14 pages, 7782 KiB

Open AccessArticle

A Novel Design of Spike-Shaped Miniaturized 4 × 4 MIMO Antenna for Wireless UWB Network Applications Using Characteristic Mode Analysis

by Ankireddy Chandra Suresh, Thatiparthi Sreenivasulu Reddy, Boddapati Taraka Phani Madhav, Samah Alshathri, Walid El-Shafai, Sudipta Das and Vishal Sorathiya

Micromachines 2023, 14(3), 612; https://doi.org/10.3390/mi14030612 - 7 Mar 2023

Cited by 7 | Viewed by 2456

Abstract

In this article, a 4 × 4 miniaturized UWB-MIMO antenna with reduced isolation is designed and analyzed using a unique methodology known as characteristic mode analysis. To minimize the antenna’s physical size and to improve the isolation, an arrangement of four symmetrical radiating [...] Read more.

In this article, a 4 × 4 miniaturized UWB-MIMO antenna with reduced isolation is designed and analyzed using a unique methodology known as characteristic mode analysis. To minimize the antenna’s physical size and to improve the isolation, an arrangement of four symmetrical radiating elements is positioned orthogonally. The antenna dimension is 40 mm × 40 mm (0.42λ₀

\times

0.42λ₀) (λ₀ is the wavelength at first lower frequency), which is printed on FR-4 material with a width of 1.6 mm and

ε_{r}

= 4.3. A square-shaped defected ground framework was placed on the ground to improve the isolation. Etching square-shaped slots on the ground plane achieved the return losses S₁₁ < −10 dB and isolation 26 dB in the entire operating band 3.2 GHz–12.44 GHz (UWB (3.1–10.6 GHz) and X-band (8 GHz–12 GHz) spectrum and achieved good isolation bandwidth of 118.15%. The outcomes of estimated and observed values are examined for MIMO inclusion factors such as DG, ECC, CCL, and MEG. The antenna’s performances, including radiation efficiency and gain, are remarkable for this antenna design. The designed antenna is successfully tested in a cutting-edge laboratory. The measured outcomes are quite similar to the modeled outcomes. This antenna is ideal for WLAN and Wi-Max applications. Full article

(This article belongs to the Special Issue New Trends in Microwave/Millimeter Antennas/Filters: From Fundamental Research to Applications)

► Show Figures

Figure 1

11 pages, 4244 KiB

Open AccessArticle

A Compact UWB Monopole Antenna with Triple Band Notches

by Han Lin, Zhongyuan Lu, Zhonggen Wang and Weidong Mu

Micromachines 2023, 14(3), 518; https://doi.org/10.3390/mi14030518 - 23 Feb 2023

Cited by 8 | Viewed by 2069

Abstract

This article presents an ultra-wideband (UWB) monopole antenna with triple band notch characteristics. The proposed antenna consists of an octagonal patch, fed with a 50 Ω line, which occupies a compact size of 40 mm × 29 mm (0.36λ × 0.26λ, λ is [...] Read more.

This article presents an ultra-wideband (UWB) monopole antenna with triple band notch characteristics. The proposed antenna consists of an octagonal patch, fed with a 50 Ω line, which occupies a compact size of 40 mm × 29 mm (0.36λ × 0.26λ, λ is computed using 2.7 GHz frequency) and resonances at a relatively low frequency (2.94 GHz). Specifically, an L-shaped stub, an inverted C-shaped slot, and a pair of U-shaped resonating structures are introduced into the design, which allow antenna to generate three band notches at 3.22–3.83 GHz, 4.49–5.05 GHz and 7.49–8.02 GHz, corresponding to WiMAX band, Indian national satellite (INSAT) band, and X-band satellite frequencies, respectively. In the center of the notched band, the antenna has lower efficiency and gain, essentially indicating that the antenna has good interference rejection performance. To evaluate its performance, the proposed antenna has been fabricated and measured, and the relevant functional parameters, such as S-parameters, voltage standing wave ratio (VSWR) and radiation property, have been studied. Full article

(This article belongs to the Special Issue New Trends in Microwave/Millimeter Antennas/Filters: From Fundamental Research to Applications)

► Show Figures

Figure 1

16 pages, 6912 KiB

Open AccessArticle

A Novel Low-Cost Compact High-Performance Flower-Shaped Radiator Design for Modern Smartphone Applications

by Zaheer Ahmed Dayo, Muhammad Aamir, Ziaur Rahman, Imran A. Khoso, Mir Muhammad Lodro, Shoaib Ahmed Dayo, Permanand Soothar, Muhammad Salman Pathan, Ahmed Jamal Abdullah Al-Gburi, Aftab Ahmed Memon and Bhawani Shankar Chowdhry

Micromachines 2023, 14(2), 463; https://doi.org/10.3390/mi14020463 - 16 Feb 2023

Cited by 1 | Viewed by 2211

Abstract

This manuscript examines the design principle and real-world validation of a new miniaturized high-performance flower-shaped radiator (FSR). The antenna prototype consists of an ultracompact square metallic patch of 0.116λ₀ × 0.116λ₀ (λ₀ is the free space wavelength at 3.67 GHz), [...] Read more.

This manuscript examines the design principle and real-world validation of a new miniaturized high-performance flower-shaped radiator (FSR). The antenna prototype consists of an ultracompact square metallic patch of 0.116λ₀ × 0.116λ₀ (λ₀ is the free space wavelength at 3.67 GHz), a rectangular microstrip feed network, and a partial metal ground plane. A novel, effective, and efficient approach based on open circuit loaded stubs is employed to achieve the antenna’s optimal performance features. Rectangular, triangular, and circular disc stubs were added to the simple structure of the square radiator, and hence, the FSR configuration was formed. The proposed antenna was imprinted on a low-cost F4B laminate with low profile thickness of 0.018λ₀, relative permittivity ε_r = 2.55, and dielectric loss tangent δ = 0.0018. The designed radiator has an overall small size of 0.256λ₀ × 0.354λ₀. The parameter study of multiple variables and their influence on the performance results has been extensively studied. Moreover, the impact of different substrate materials, impedance bandwidths, resonance tuning, and impedance matching has also been analyzed. The proposed antenna model has been designed, simulated, and fabricated. The designed antenna exhibits a wide bandwidth of 5.33 GHz ranging from 3.67 to 9.0 GHz at 10 dB return loss, which resulted in an 83.6% fractional impedance bandwidth; a maximum gain of 7.3 dBi at 8.625 GHz; optimal radiation efficiency of 89% at 4.5 GHz; strong intensity current flow across the radiator; and stable monopole-like far-field radiation patterns. Finally, a comparison between the scientific results and newly published research has been provided. The antenna’s high-performance simulated and measured results are in a good agreement; hence, they make the proposed antenna an excellent choice for modern smartphones’ connectivity with the sub-6 GHz frequency spectrum of modern fifth-generation (5G) mobile communication application. Full article

(This article belongs to the Special Issue New Trends in Microwave/Millimeter Antennas/Filters: From Fundamental Research to Applications)

► Show Figures

Figure 1

16 pages, 2139 KiB

Open AccessArticle

Wideband Circularly Polarized Millimeter Wave Hemispherical Dielectric Resonator Antenna

by Meshari D. Alanazi and Salam K. Khamas

Micromachines 2023, 14(2), 436; https://doi.org/10.3390/mi14020436 - 12 Feb 2023

Cited by 3 | Viewed by 1872

Abstract

A novel approach is proposed to design a circularly polarized (CP) hemispherical dielectric resonator antenna (DRA) with a wide axial ratio (AR) bandwidth by incorporating an additional dielectric substrate between the antenna and the ground plane. This is in addition to the lower [...] Read more.

A novel approach is proposed to design a circularly polarized (CP) hemispherical dielectric resonator antenna (DRA) with a wide axial ratio (AR) bandwidth by incorporating an additional dielectric substrate between the antenna and the ground plane. This is in addition to the lower feeding substrate that is located between the ground plane on one side and the feeding microstrip line on the other side. Adding another substrate on top of the ground plane provided an additional degree of freedom in the design that facilitated the achievement of ab 18% AR bandwidth. In addition, an integrated hemispherical DRA and perforated substrate configuration was utilized to achieve optimum effective substrate permittivity and overcome the DRA alignment and assembly challenges while maintaining the achieved wide CP bandwidth. A close agreement was achieved between measurements and simulations. Full article

(This article belongs to the Special Issue New Trends in Microwave/Millimeter Antennas/Filters: From Fundamental Research to Applications)

► Show Figures

Figure 1

13 pages, 4165 KiB

Open AccessArticle

Filtenna with Frequency Reconfigurable Operation for Cognitive Radio and Wireless Applications

by Mahmoud A. Abdelghany, Wael A. E. Ali, Hesham A. Mohamed and Ahmed A. Ibrahim

Micromachines 2023, 14(1), 160; https://doi.org/10.3390/mi14010160 - 8 Jan 2023

Cited by 7 | Viewed by 2196

Abstract

A reconfigurable wideband monopole antenna is introduced in this paper for cognitive radio and wireless applications. The reconfigurability was achieved by four varactor diodes embedded in the band pass filter (BPF) structure which was integrated with the suggested antenna through its feed line. [...] Read more.

A reconfigurable wideband monopole antenna is introduced in this paper for cognitive radio and wireless applications. The reconfigurability was achieved by four varactor diodes embedded in the band pass filter (BPF) structure which was integrated with the suggested antenna through its feed line. The simulated impedance characteristics coped with the measured ones after fabricating the suggested model with/without the reconfigurable BPF. Furthermore, the model achieved the desired radiation characteristics in terms of radiation pattern with acceptable gain values at the selected frequencies within the achieved frequency range (1.3–3 GHz). Full article

(This article belongs to the Special Issue New Trends in Microwave/Millimeter Antennas/Filters: From Fundamental Research to Applications)

► Show Figures

Figure 1

14 pages, 3828 KiB

Open AccessArticle

A Printed Reconfigurable Monopole Antenna Based on a Novel Metamaterial Structures for 5G Applications

by Saba T. Al-Hadeethi, Taha A. Elwi and Abdullahi A. Ibrahim

Micromachines 2023, 14(1), 131; https://doi.org/10.3390/mi14010131 - 3 Jan 2023

Cited by 13 | Viewed by 2195

Abstract

A novel antenna structure is constructed from cascading multi-stage metamaterial (MTM) unit cells-based printed monopole antenna for 5G mobile communication networks. The proposed antenna is constructed from a printed conductive trace that fetches four MTM unit cells through four T-Resonators (TR) structures. Such [...] Read more.

A novel antenna structure is constructed from cascading multi-stage metamaterial (MTM) unit cells-based printed monopole antenna for 5G mobile communication networks. The proposed antenna is constructed from a printed conductive trace that fetches four MTM unit cells through four T-Resonators (TR) structures. Such a combination is introduced to enhance the antenna gain-bandwidth products at sub-6GHz bands after exiting the antenna with a coplanar waveguide (CPW) feed. The antenna circuitry is fabricated by etching a copper layer that is mounted on Taconic RF-43 substrate. Therefore, the proposed antenna occupies an effective area of 51 × 24 mm². The proposed antenna provides an acceptable matching impedance with S₁₁ ≤ −10 dB at 3.7 GHz, 4.6 GHz, 5.2 GHz, and 5.9 GHz. The antenna radiation patterns are evaluated at the frequency bands of interest with a gain average of 9.1–11.6 dBi. Later, to control the antenna performance, four optical switches based on LDR resistors are applied to control the antenna gain at 5.85 GHz, which is found to vary from 2 dBi to 11.6 dBi after varying the value of the LDR resistance from 700 Ω to 0 Ω, in descending manner. It is found that the proposed antenna provides an acceptable bit error rate (BER) with varying the antenna gain in a very acceptable manner in comparison to the ideal performance. Finally, the proposed antenna is fabricated to be tested experimentally in in free space and in close to the human body for portable applications. Full article

(This article belongs to the Special Issue New Trends in Microwave/Millimeter Antennas/Filters: From Fundamental Research to Applications)

► Show Figures

Figure 1

17 pages, 6671 KiB

Open AccessArticle

Optically Remote Control of Miniaturized 3D Reconfigurable CRLH Printed Self-Powered MIMO Antenna Array for 5G Applications

by Hayder H. Al-khaylani, Taha A. Elwi and Abdullahi A. Ibrahim

Micromachines 2022, 13(12), 2061; https://doi.org/10.3390/mi13122061 - 24 Nov 2022

Cited by 11 | Viewed by 1963

Abstract

A novel design of a reconfigurable MIMO antenna array of a 3D geometry-based solar cell integration that is operating at sub-6 GHz for self-power applications in a 5G modern wireless communication network. The proposed antenna array provides three main frequency bands around 3.6 [...] Read more.

A novel design of a reconfigurable MIMO antenna array of a 3D geometry-based solar cell integration that is operating at sub-6 GHz for self-power applications in a 5G modern wireless communication network. The proposed antenna array provides three main frequency bands around 3.6 GHz, 3.9 GHz, and 4.9 GHz, with excellent matching impedance of S₁₁ ≤ −10 dB. The proposed MIMO array is constructed from four antenna elements arranged on a cubical structure to provide a low mutual coupling, below −20 dB, over all frequency bands of interest. Each antenna element is excited with a coplanar waveguide (CPW). The proposed radiation patterns are controlled with two optical switches of Light Dependent Resistors (LDRs). The proposed antenna array is fabricated and tested experimentally in terms of S-parameters, gain and radiation patterns. The maximum gain is found to be 3.6 dBi, 6.9 dBi, and 3.5 dBi at 3.6 GHz, 3.9 GHz, and 4.9 GHz, respectively. It is realized that the proposed array realizes a significant beam forming by splitting the antenna beam and changing the main lobe direction at 3.9 GHz after changing LDR switching statuses. Such an antenna array is found to be very applicable for femtocell wireless communication networks in the 5G systems. Full article

(This article belongs to the Special Issue New Trends in Microwave/Millimeter Antennas/Filters: From Fundamental Research to Applications)

► Show Figures

Figure 1

18 pages, 14826 KiB

Open AccessArticle

Design of Wideband Decoupling Antenna Pairs for 5G Portable Devices at N77/N78/N79 Bands

by Kaiwen Du, Yongshun Wang, Lijun Zhang and Yao Hu

Micromachines 2022, 13(11), 1964; https://doi.org/10.3390/mi13111964 - 12 Nov 2022

Cited by 2 | Viewed by 1812

Abstract

We proposed an antenna pair that is applicable for mobile terminals: a type of coupling feed planar antenna that has a size of

28 \times 6 {mm}^{2}

, a wide band, coupling suppression and compact size. Different from the conventional antenna [...] Read more.

We proposed an antenna pair that is applicable for mobile terminals: a type of coupling feed planar antenna that has a size of

28 \times 6 {mm}^{2}

, a wide band, coupling suppression and compact size. Different from the conventional antenna design, the process of band expansion comes from a dual-band antenna pair and is based on characteristic modes theory (CMA). By observing characteristic current distributions, the optimization emphasis is placed on current sensitive parts in antenna structures, which is an effective method to create or modify resonant points for exciting band potential. Meanwhile, the multiple defective ground structure (DGS) is introduced for isolation enhancement. The −10 dB bandwidth of 3.23–5.24 GHz can be realized, and the isolation of two antenna pairs with only 2 mm spacing is lower (−17.34 dB). The eight-port MIMO system constructed by four proposed antenna pairs has been fabricated. The simulated and measured results of MIMO indicate that its −10 dB operating bandwidth can work at N77/N78/N79/WLAN 5 GHz bands. Moreover, a lower ECC of less than 0.04 and a high efficiency of more than 60% can be obtained, which confirms that it is capable of excellent data transmission as a terminal MIMO antenna system. Full article

(This article belongs to the Special Issue New Trends in Microwave/Millimeter Antennas/Filters: From Fundamental Research to Applications)

► Show Figures

Figure 1

Journal Menu

Journal Browser

New Trends in Microwave/Millimeter Antennas/Filters: From Fundamental Research to Applications

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Benefits of Publishing in a Special Issue

Published Papers (20 papers)

Editorial

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI