Miniaturized Microwave Components and Devices

A special issue of Micromachines (ISSN 2072-666X). This special issue belongs to the section "E:Engineering and Technology".

Deadline for manuscript submissions: closed (30 March 2022) | Viewed by 42887

Special Issue Editor


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Guest Editor
Faculty of Electronics, Telecommunications and Informatics, Gdansk University of Technology, 80-233 Gdansk, Poland
Interests: microwave/RF circuit miniaturization, surrogate-based modeling and optimization, engineering design automation, computer-aided design, antenna engineering

Special Issue Information

Dear Colleagues,

Size reduction is an important prerequisite for the development of modern microwave circuits and components. This topic has attracted much attention in recent years due to the rapid expansion of commercial, industrial, and military markets aimed at low-cost, small-size, high-performance microwave devices. The diversity of their applications includes—but is not limited to—mobile communication, telemedicine, remote sensing, defense electronics, and portable measurement equipment. Miniaturization has been a prevailing trend in the electronics industry for several decades now and a catalyst for persistent technological innovation worldwide. Unfortunately, Moore’s Law, which can be applied to describe the tremendous integration capabilities of semiconductor devices, does not apply to many areas of microwave engineering. This is because a proper operation of a system that heavily relies on wave phenomena cannot be achieved by replacing its distributed components with lumped elements. The longitudinal dimensions of the distributed components must remain fixed with respect to the guided wavelength to preserve functionality. With the ubiquitous downshifting of the operating frequency spectrum, handling large layouts of conventional microwave structures has become more challenging than ever. For the reasons above, the development of efficient miniaturization schemes represents an important research direction with the potential to contribute to the progress in applied microwave technologies.

 

The objective of this Special Issue is to report on new technologies that allow obtaining compact microwave components and devices; innovative miniaturization methods of conventional microwave circuits in standard technologies; and customized computer-aided design and optimization methodologies specifically tailored to address modeling, design, and prototyping challenges pertinent to compact microwave components and devices.

Dr. Piotr Kurgan
Guest Editor

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Keywords

  • Miniaturization of microwave circuits and components
  • Computer-aided design of compact microwave devices
  • Efficient modeling and design optimization of miniaturized microwave components and devices

Published Papers (16 papers)

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8 pages, 2518 KiB  
Article
Design of Quad-Band Bandpass Filter Using Dual-Mode SLRs and Coupled-Line for DCS/WLAN/WiMAX and 5G Applications
by Sugchai Tantiviwat, Siti Zuraidah Ibrahim, Mohammad Shahrazel Razalli and Ping Jack Soh
Micromachines 2022, 13(5), 700; https://doi.org/10.3390/mi13050700 - 29 Apr 2022
Cited by 3 | Viewed by 1231
Abstract
A design of a microstrip quad-band BPF with flexibly controlled bandwidth is presented in this paper. Two dual-mode short-circuited SLRs with a common via-hole are proposed, which are utilized to obtain the first and second passband, while the third passband is generated by [...] Read more.
A design of a microstrip quad-band BPF with flexibly controlled bandwidth is presented in this paper. Two dual-mode short-circuited SLRs with a common via-hole are proposed, which are utilized to obtain the first and second passband, while the third passband is generated by implementing the second-order half-wavelength coupled-line resonator. Another dual-mode open-circuited SLR can be operated at the fourth passband. The proposed quad-band BPF is centered at 1.80/2.45/3.50/4.90 GHz for DCS/WLAN/WiMAX and 5G applications. By appropriately choosing the lengths of the four sets of resonators, all passbands can be fully varied independently with minimal effect on other passbands. Moreover, the bandwidth of each passband can be flexibly controlled by tuning the coupling parameters. The dimension of the fabricated proposed filter is about 0.12 × 0.20 λg, indicating the compactness of the design, whereas the measurements are in good agreement with the simulated results. The measured S11 are at least 12 dB in the four passbands. The passbands S21 are approximately 0.65, 1.42, 0.78, and 1.20 dB, which exhibit low insertion loss at the passband frequency of the first, second, third, and fourth passband, respectively. Full article
(This article belongs to the Special Issue Miniaturized Microwave Components and Devices)
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18 pages, 7037 KiB  
Article
An Oval-Square Shaped Split Ring Resonator Based Left-Handed Metamaterial for Satellite Communications and Radar Applications
by Ismatul Nisak Idrus, Mohammad Rashed Iqbal Faruque, Sabirin Abdullah, Mayeen Uddin Khandaker, Nissren Tamam and Abdelmoneim Sulieman
Micromachines 2022, 13(4), 578; https://doi.org/10.3390/mi13040578 - 07 Apr 2022
Cited by 11 | Viewed by 2418
Abstract
Development of satellite and radar applications has been continuously studied to reach the demand in the recent communication technology. In this study, a new oval-square-shaped split-ring resonator with left-handed metamaterial properties was developed for C-band and X-band applications. The proposed metamaterial was fabricated [...] Read more.
Development of satellite and radar applications has been continuously studied to reach the demand in the recent communication technology. In this study, a new oval-square-shaped split-ring resonator with left-handed metamaterial properties was developed for C-band and X-band applications. The proposed metamaterial was fabricated on 9 × 9 × 0.508 mm3 size of Rogers RO4003C substrate. The proposed metamaterial structure was designed and simulated using Computer Simulation Technique (CST) Microwave Studio with the frequency ranging between 0 to 12 GHz. The simulated result of the proposed design indicated dual resonance frequency at 5.52 GHz (C-band) and 8.81 GHz (X-band). Meanwhile, the experimental result of the proposed design demonstrated dual resonance frequency at 5.53 GHz (C-band) and 8.31 GHz (X-band). Therefore, with a slight difference in the dual resonance frequency, the simulated result corresponded to the experimental result. Additionally, the proposed design exhibited the ideal properties of electromagnetic which is left-handed metamaterial (LHM) behavior. Hence, the metamaterial structure is highly recommended for satellite and radar applications. Full article
(This article belongs to the Special Issue Miniaturized Microwave Components and Devices)
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13 pages, 3121 KiB  
Article
Optimized Super-Wideband MIMO Antenna with High Isolation for IoT Applications
by Adnan Khurshid, Jian Dong, Mir Swad Ahmad and Ronghua Shi
Micromachines 2022, 13(4), 514; https://doi.org/10.3390/mi13040514 - 25 Mar 2022
Cited by 15 | Viewed by 2159
Abstract
A compact, low profile, multiple-input–multiple-output (MIMO) diversity antenna with super-wideband (SWB) characteristics has been proposed. The proposed antenna comprises four symmetric monopole-radiating elements printed on low-cost FR4 substrate with the slotted ground plane. The single antenna of a monopole structure and a quad-port [...] Read more.
A compact, low profile, multiple-input–multiple-output (MIMO) diversity antenna with super-wideband (SWB) characteristics has been proposed. The proposed antenna comprises four symmetric monopole-radiating elements printed on low-cost FR4 substrate with the slotted ground plane. The single antenna of a monopole structure and a quad-port MIMO antenna, with the dimensions of 30 × 20 mm2 and 60 × 55 mm2, respectively, are ideal for IoT and high-speed data applications. The proposed MIMO antenna has a high diversity gain and low envelope correlation coefficient (ECC) within the frequency range. Simulated results demonstrate the performance of the MIMO-SWB antenna, which operates from 2.3 to 23 GHz, with a high isolation level over 20 dB in the achieved frequency band. Moreover, the proposed MIMO antenna has been investigated with mirror fashion and orthogonal structure. Both structures provide similar results except for mutual coupling performance. The orthogonal adjustment for high isolation achieves better results with the proposed model. Further, the prototype of the proposed antenna is fabricated and measured effectively. Simulated and measured results show good agreement for super-wideband applications. Full article
(This article belongs to the Special Issue Miniaturized Microwave Components and Devices)
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9 pages, 6531 KiB  
Article
Miniaturized Band Pass Filter Design Using Half Mode Substrate Integrated Coaxial Resonators
by Min-Hua Ho, Chung-I G. Hsu, Kun-Hua Tang and Wanchu Hong
Micromachines 2022, 13(3), 389; https://doi.org/10.3390/mi13030389 - 28 Feb 2022
Cited by 4 | Viewed by 2066
Abstract
The contribution of this work is to propose a half-mode substrate integrated coaxial resonator (HMSICR) and its application in bandpass filter (BPF) design. The proposed HMSICR is formed by evenly bisecting a square substrate integrated coaxial resonator (SICR), which is a cavity composed [...] Read more.
The contribution of this work is to propose a half-mode substrate integrated coaxial resonator (HMSICR) and its application in bandpass filter (BPF) design. The proposed HMSICR is formed by evenly bisecting a square substrate integrated coaxial resonator (SICR), which is a cavity composed of two dielectric substrates and three metal layers. The SICR’s sidewalls are mimicked by periodically spaced thru-via arrays, and a circular patch is embedded in the middle metal layer of the SICR with the patch shorted to the cavity’s bottom wall by a circular array of blind vias. This HMSICR can drastically lower the cavity’s resonance frequency. The achieved frequency reduction rate of the proposed HMSICR, as compared with that of its conventional substrate integrated waveguide (SIW) cavity counterpart, reaches 70%. A sample four-HMSICR BPF is built for the circuit verification measurement. To further reduce the sample filter’s area, the composing HMSICRs are vertically stacked in a back-to-back configuration. We believe that its obtained size-reduction rate reaches the highest record. Full article
(This article belongs to the Special Issue Miniaturized Microwave Components and Devices)
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16 pages, 5938 KiB  
Article
Metamaterial-Inspired Electrically Compact Triangular Antennas Loaded with CSRR and 3 × 3 Cross-Slots for 5G Indoor Distributed Antenna Systems
by Arshad Karimbu Vallappil, Bilal A. Khawaja, Mohamad Kamal A. Rahim, Muhammad Naeem Iqbal and Hassan T. Chattha
Micromachines 2022, 13(2), 198; https://doi.org/10.3390/mi13020198 - 27 Jan 2022
Cited by 11 | Viewed by 3104
Abstract
In this article, two distinct kinds of metamaterial (MTM) antennas are proposed for fifth-generation (5G) indoor distributed antenna systems (IDAS). Both antennas operate in the sub-6 GHz 5G band, i.e., 3.5 GHz. The antenna’s radiating structure is based on a combination of triangular [...] Read more.
In this article, two distinct kinds of metamaterial (MTM) antennas are proposed for fifth-generation (5G) indoor distributed antenna systems (IDAS). Both antennas operate in the sub-6 GHz 5G band, i.e., 3.5 GHz. The antenna’s radiating structure is based on a combination of triangular and rectangular patches, as well as two complementary split-ring resonators (CSRR) unit-cells etched on the top layer. The bottom layer of the first MTM antenna is a complete ground plane, while the bottom layer of the second MTM antenna is etched by a 3 × 3 cross-slot MTM structure on the ground plane. The use of these structures on the ground plane improves the antenna bandwidth. The proposed antennas are designed using two different substrates i.e., a high-end Rogers thermoset microwave materials (TMM4) substrate (h = 1.524 mm/εr = 4.5/tan δ = 0.002) and a low-end flame-resistant (FR4) epoxy glass substrate (h = 1.6 mm/εr = 4.3/tan δ = 0.025), respectively. The antenna designs are simulated using CST microwave studio, and in the end, the antenna fabrication is performed using FR4 substrate, and the results are compared. Furthermore, parametric analysis and comparative studies are carried out to investigate the performance of the designed antennas. The simulated and measured results are presented for various parameters such as return-loss, gain, and radiation pattern. The two MTM antennas have an overall dimension of 18 × 34 mm2, demonstrating that the proposed design is 60 percent smaller than a standard microstrip patch antenna (MPA). The two proposed MTM antenna designs with complete ground plane and 3 × 3 cross-slot MTM on the bottom layer using FR4 substrate have a measured gain/bandwidth characteristic of 100 MHz/2.6 dBi and 700 MHz/2.3 dBi, respectively. Full article
(This article belongs to the Special Issue Miniaturized Microwave Components and Devices)
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14 pages, 5988 KiB  
Article
A New Octagonal Close Ring Resonator Based Dumbbell-Shaped Tuning Fork Perfect Metamaterial Absorber for C- and Ku-Band Applications
by Md Salah Uddin Afsar, Mohammad Rashed Iqbal Faruque, Md Bellal Hossain, Air Mohammad Siddiky, Mayeen Uddin Khandaker, Amal Alqahtani and D. A. Bradley
Micromachines 2022, 13(2), 162; https://doi.org/10.3390/mi13020162 - 22 Jan 2022
Cited by 15 | Viewed by 2577
Abstract
In this paper, a new octagonal close ring resonator (OCRR)-based dumbbell-shaped tuning fork perfect metamaterial absorber for C- and Ku-band applications is presented. This design is a new combination of an octagonal ring close ring resonator with two dumbbell-shaped tuning forks metal strips [...] Read more.
In this paper, a new octagonal close ring resonator (OCRR)-based dumbbell-shaped tuning fork perfect metamaterial absorber for C- and Ku-band applications is presented. This design is a new combination of an octagonal ring close ring resonator with two dumbbell-shaped tuning forks metal strips integrated on epoxy resin dielectric substrate. The proposed perfect metamaterial absorber (PMA) is assessed by finite-integration technique (FIT)-based electromagnetic simulator-Computer simulation technology (CST) software. The anticipated assembly reveals dual resonance frequencies of 6.45 GHz and 14.89 GHz at 99.15% and 99.76% absorption, respectively, for TE incidence. The projected design is augmented through various types of parametric studies, such as design optimization, the effect of the octagonal ring resonator width, and varying the split gap of the double tuning fork. The numerical results are also investigated and verified using the equivalent circuit model, another electromagnetic simulator high frequency structural simulator (HFSS), and different array combinations that showed very negligible disparity. The TE polarization wave is applied to analyze the absorption separately and oblique incidence angle showing polarization insensitivity up to 30° and wide incident angle up to 60°. The presented metamaterial absorber is suitable for satellite communication bands, stealth-coating technology, and defense and security applications. Full article
(This article belongs to the Special Issue Miniaturized Microwave Components and Devices)
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26 pages, 33679 KiB  
Article
A Compact Dual-Band Notched UWB Antenna for Wireless Applications
by Om Prakash Kumar, Pramod Kumar and Tanweer Ali
Micromachines 2022, 13(1), 12; https://doi.org/10.3390/mi13010012 - 23 Dec 2021
Cited by 22 | Viewed by 3819
Abstract
This article presents the design and analysis of a V-shaped ultrawideband (UWB) antenna and dual-band UWB notch antenna. A rectangular slot is cut into a semicircular partial ground plane of the antenna to achieve ultrawide bandwidth. A U-shape slot is etched on a [...] Read more.
This article presents the design and analysis of a V-shaped ultrawideband (UWB) antenna and dual-band UWB notch antenna. A rectangular slot is cut into a semicircular partial ground plane of the antenna to achieve ultrawide bandwidth. A U-shape slot is etched on a V-shaped patch that radiates, and an inverted U-shape parasitic resonator is placed beside the feedline to generate dual-band notch characteristics. The overall dimension of the proposed antenna is 28×23 mm2. The proposed UWB antenna has a gain of 9.8 dB, S11 < −10 dB, impedance bandwidth in the range of 3.4 to 12.3 GHz, response with a linear phase, group delay <1 ns, and stable radiation pattern. The UWB notch antenna shows strong rejection in the WLAN band from 5.15 to 5.8 GHz with a notch at 5.6 GHz and X band from 9.1 to 10.5 GHz with a sharp notch at 9.6 GHz, having a S11 < −10 dB impedance bandwidth ranging from 3.2 to 11.7 GHz. This antenna also exhibits a stable radiation pattern, group delay <1 ns, and linear phase response throughout the bandwidth except at the rejection frequencies. Full article
(This article belongs to the Special Issue Miniaturized Microwave Components and Devices)
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14 pages, 39715 KiB  
Article
A 20–44 GHz Wideband LNA Design Using the SiGe Technology for 5G Millimeter-Wave Applications
by Warsha Balani, Mrinal Sarvagya, Tanweer Ali, Ajit Samasgikar, Pradeep Kumar, Sameena Pathan and Manohara Pai M M
Micromachines 2021, 12(12), 1520; https://doi.org/10.3390/mi12121520 - 07 Dec 2021
Cited by 2 | Viewed by 2665
Abstract
This paper presents the design and implementation of a low-noise amplifier (LNA) for millimeter-wave (mm-Wave) 5G wireless applications. The LNA was based on a common-emitter configuration with cascode amplifier topology using an IHP’s 0.13 μm Silicon Germanium (SiGe) heterojunction bipolar transistor (HBT) [...] Read more.
This paper presents the design and implementation of a low-noise amplifier (LNA) for millimeter-wave (mm-Wave) 5G wireless applications. The LNA was based on a common-emitter configuration with cascode amplifier topology using an IHP’s 0.13 μm Silicon Germanium (SiGe) heterojunction bipolar transistor (HBT) whose f_T/f_MAX/gate-delay is 360/450 GHz/2.0 ps, utilizing transmission lines for simultaneous noise and input matching. A noise figure of 3.02–3.4 dB was obtained for the entire wide bandwidth from 20 to 44 GHz. The designed LNA exhibited a gain (S_21) greater than 20 dB across the 20–44 GHz frequency range and dissipated 9.6 mW power from a 1.2 V supply. The input reflection coefficient (S_11) and output reflection coefficient (S_22) were below −10 dB, and reverse isolation (S_12) was below −55 dB for the 20–44 GHz frequency band. The input 1 dB (P1dB) compression point of −18 dBm at 34.5 GHz was obtained. The proposed LNA occupies only a 0.715 mm2 area, with input and output RF (Radio Frequency) bond pads. To the authors’ knowledge, this work evidences the lowest noise figure, lowest power consumption with reasonable highest gain, and highest bandwidth attained so far at this frequency band in any silicon-based technology. Full article
(This article belongs to the Special Issue Miniaturized Microwave Components and Devices)
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17 pages, 2832 KiB  
Article
Efficient Surrogate Modeling and Design Optimization of Compact Integrated On-Chip Inductors Based on Multi-Fidelity EM Simulation Models
by Piotr Kurgan
Micromachines 2021, 12(11), 1341; https://doi.org/10.3390/mi12111341 - 30 Oct 2021
Cited by 3 | Viewed by 1689
Abstract
High-performance and small-size on-chip inductors play a critical role in contemporary radio-frequency integrated circuits. This work presents a reliable surrogate modeling technique combining low-fidelity EM simulation models, response surface approximations based on kriging interpolation, and space mapping technology. The reported method is useful [...] Read more.
High-performance and small-size on-chip inductors play a critical role in contemporary radio-frequency integrated circuits. This work presents a reliable surrogate modeling technique combining low-fidelity EM simulation models, response surface approximations based on kriging interpolation, and space mapping technology. The reported method is useful for the development of broadband and highly accurate data-driven models of integrated inductors within a practical timeframe, especially in terms of the computational expense of training data acquisition. Application of the constructed surrogate model for rapid design optimization of a compact on-chip inductor is demonstrated. The optimized EM-validated design solution can be reached at a low computational cost, which is a considerable improvement over existing approaches. In addition, this work provides a description and illustrates the usefulness of a multi-fidelity design optimization method incorporating EM computational models of graduated complexity and local polynomial approximations managed by an output space mapping optimization framework. As shown by the application example, the final design solution is obtained at the cost of a few high-fidelity EM simulations of a small-size integrated coil. A supplementary description of variable-fidelity EM computational models and a trade-off between model accuracy and its processing time complements the work. Full article
(This article belongs to the Special Issue Miniaturized Microwave Components and Devices)
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15 pages, 9547 KiB  
Article
A Miniaturized Quad-Stopband Frequency Selective Surface with Convoluted and Interdigitated Stripe Based on Equivalent Circuit Model Analysis
by Jian Dong, Yan Ma, Zhuangzhuang Li and Jinjun Mo
Micromachines 2021, 12(9), 1027; https://doi.org/10.3390/mi12091027 - 27 Aug 2021
Cited by 13 | Viewed by 2564
Abstract
This paper presents a miniaturized frequency selective surface (FSS) based on the convoluted and interdigitated stripe with multiple narrow passbands/wide stopbands in the L-/S-/C-/X-/Ku-/K-band. By using the convoluted and interdigitated stripe, the coupling inside is well controlled, so that the spatial efficiency is [...] Read more.
This paper presents a miniaturized frequency selective surface (FSS) based on the convoluted and interdigitated stripe with multiple narrow passbands/wide stopbands in the L-/S-/C-/X-/Ku-/K-band. By using the convoluted and interdigitated stripe, the coupling inside is well controlled, so that the spatial efficiency is maximized to provide a high miniaturization. An equivalent circuit model is presented to reveal the working mechanism of the proposed FSS. The proposed structure forms four transmission band rejections of 3 dB in 1–6.65 GHz, 8.35–16.9 GHz, 18.0–24 GHz, and 24.50–27.84 GHz. The size of the unit cell is 0.09λ0 × 0.09λ0, where λ0 is the wavelength of the first resonance frequency. The proposed FSS has a good angle stability and polarization stability in a scanning range up to 60°. For verification, an FSS prototype has been fabricated and measured. The measured results were in agreement with the simulated results. The proposed FSS can be used in practical applications such as radomes, antenna reflectors, and spatial filters. Full article
(This article belongs to the Special Issue Miniaturized Microwave Components and Devices)
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15 pages, 5764 KiB  
Article
Modified Hexagonal Split Ring Resonator Based on an Epsilon-Negative Metamaterial for Triple-Band Satellite Communication
by Salah Uddin Afsar, Mohammad Rashed Iqbal Faruque, Mohammad Jakir Hossain, Mayeen Uddin Khandaker, Hamid Osman and Sultan Alamri
Micromachines 2021, 12(8), 878; https://doi.org/10.3390/mi12080878 - 26 Jul 2021
Cited by 18 | Viewed by 3291
Abstract
A triple-band epsilon-negative (ENG) metamaterial based on a split ring resonator (SSR) with a modified hexagonal-shaped metal strip proposed in this study is a new combination of a single slit square resonator and a modified hexagonal-shaped metal strip. The desired unit cell FR-4 [...] Read more.
A triple-band epsilon-negative (ENG) metamaterial based on a split ring resonator (SSR) with a modified hexagonal-shaped metal strip proposed in this study is a new combination of a single slit square resonator and a modified hexagonal-shaped metal strip. The desired unit cell FR-4 (lossy) that was selected as the substrate was 1.6 mm thick. Following the assessment of the unit cell, a high-frequency electromagnetic simulator like the computer simulation technology (CST) microwave studio was applied to assess the S-parameters. The proposed design exhibited resonance at 2.89, 9.42, and 15.16 GHz. The unit cell also demonstrated negative permittivity in the frequency ranges 2.912–3.728 GHz, 9.552–10.144 GHz, and 15.216–17.328 GHz, along with a negative refractive index. An effective medium ratio (EMR) of 11.53 is an indicator of the goodness of the metamaterial unit cell. It is deliberate at the lowermost resonance frequency of 2.89 GHz. Moreover, the simulated results that were validated using HFSS and equivalent circuit model indicated slight variations. The proposed design was finalised based on several parametric studies, including design optimisation, different unit cell sizes, various substrate materials, and different electromagnetic (EM) field propagations. The proposed triple band (S, X, and Ku bands) negative permittivity metamaterial unit cell can be utilised for various wireless applications, such as microwave communication, satellite communication, and long-distance radio communication. Full article
(This article belongs to the Special Issue Miniaturized Microwave Components and Devices)
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12 pages, 7301 KiB  
Article
Slotted E-Shaped Meta-Material Decoupling Slab for Densely Packed MIMO Antenna Arrays
by Karim H. Moussa, Ahmed S. I. Amar, Mohamed Mabrouk and Heba G. Mohamed
Micromachines 2021, 12(8), 873; https://doi.org/10.3390/mi12080873 - 25 Jul 2021
Cited by 10 | Viewed by 2090
Abstract
In contemporary wireless communication systems, the multiple-input and multiple-output systems are extensively utilized due to their enhanced spectral efficiency and diversity. Densely packed antenna arrays play an important role in such systems to enhance their spatial diversity, array gain, and beam scanning capabilities. [...] Read more.
In contemporary wireless communication systems, the multiple-input and multiple-output systems are extensively utilized due to their enhanced spectral efficiency and diversity. Densely packed antenna arrays play an important role in such systems to enhance their spatial diversity, array gain, and beam scanning capabilities. In this article, a slotted meta-material decoupling slab (S-MTM-DS) with dual reflexes slotted E-shapes and an inductive stub is proposed. Its function was validated when located between two microstrip patch antenna elements to reduce the inter-element spacing, the mutual coupling, the return losses, and manufacturing costs due to size reduction. A prototype is simply fabricated in a volume of 67.41 × 33.49 × 1.6 mm3 and frequency-span measured from 8.4:11 GHz. At 9.4 GHz frequency, the spaces between the transmitting elements are decreased to 0.57 of the free space wavelength. When the proposed isolation S-MTM-DS is applied, the average isolation among them is measured to be −36 dB, the operational bandwidth is enhanced to be 1.512 GHz, the fractional bandwidth improved to be 16.04%, and the return losses are decreased to be −26.5 dB at 9.4 GHz center frequency. Consequently, the proposed design has the potential to be implemented simply in wireless contemporary communication schemes. Full article
(This article belongs to the Special Issue Miniaturized Microwave Components and Devices)
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10 pages, 16865 KiB  
Article
Compact Full Ka-Band Waveguide Directional Coupler Based on Rectangular Aperture Array with Stairs
by Xida Deng, Ge Dong, Xuan Dai and Jinxiang Deng
Micromachines 2021, 12(7), 745; https://doi.org/10.3390/mi12070745 - 25 Jun 2021
Cited by 2 | Viewed by 2538
Abstract
This article presents a compact 3 dB waveguide directional coupler with full waveguide bandwidth. It consists of a pair of rectangular waveguides with stairs structures in the coupling region. The waveguides are placed parallel to each other along their broad wall, which has [...] Read more.
This article presents a compact 3 dB waveguide directional coupler with full waveguide bandwidth. It consists of a pair of rectangular waveguides with stairs structures in the coupling region. The waveguides are placed parallel to each other along their broad wall, which has a rectangular aperture array. The compact size, broad bandwidth, good in-band coupling flatness, and good return loss are achieved by using the proposed structure. For verification purposes, a prototype of the proposed coupler was designed, manufactured, and measured. The experimental results show that over the full waveguide bandwidth a return loss of input port better than 17.46 dB, coupling strength varying between −2.74 dB and −3.80 dB, power-split unbalance within 0.76 dB, and an isolation better than 20.82 dB were obtained. The length of the coupling region was only 15.82 mm. Full article
(This article belongs to the Special Issue Miniaturized Microwave Components and Devices)
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8 pages, 3149 KiB  
Article
A Compact Planar Dual-Band Multiple-Input and Multiple-Output Antenna with High Isolation for 5G and 4G Applications
by Rong Yang, Shuqi Xi, Qibo Cai, Zhizhou Chen, Xiaohang Wang and Gui Liu
Micromachines 2021, 12(5), 544; https://doi.org/10.3390/mi12050544 - 10 May 2021
Cited by 26 | Viewed by 2238
Abstract
In this paper, a compact planar dual-band multiple-input and multiple-output (MIMO) antenna with high isolation is presented to satisfy the increasing requirements of wireless communication. The proposed antenna array consists of two identical radiating elements which are fed through micro-strip lines. A rectangular [...] Read more.
In this paper, a compact planar dual-band multiple-input and multiple-output (MIMO) antenna with high isolation is presented to satisfy the increasing requirements of wireless communication. The proposed antenna array consists of two identical radiating elements which are fed through micro-strip lines. A rectangular micro-strip stub with defected ground plane is employed to achieve a high isolation which is less than −15 dB between the two antenna elements. The size of the entire MIMO antenna is 32 × 32 × 1.59 mm3, which is printed on an FR4 substrate. The proposed MIMO antenna is optimized to operate in 2.36–2.59 GHz and 3.17–3.77 GHz bands, which can cover the fifth-generation (5G) n7 (2.5–2.57 GHz) and the fourth-generation (4G) Long Term Evolution (LTE) band 42 (3.4–3.6 GHz). The proposed MIMO antenna is feasible for the 5G and 4G applications. Full article
(This article belongs to the Special Issue Miniaturized Microwave Components and Devices)
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12 pages, 35415 KiB  
Article
Dual-Band MIMO Antenna for 5G/WLAN Mobile Terminals
by Jianlin Huang, Guiting Dong, Qibo Cai, Zhizhou Chen, Limin Li and Gui Liu
Micromachines 2021, 12(5), 489; https://doi.org/10.3390/mi12050489 - 26 Apr 2021
Cited by 29 | Viewed by 3201
Abstract
This paper presents a dual-band four-element multiple-input-multiple-output (MIMO) array for the fifth generation (5G) mobile communication. The proposed antenna is composed of an open-loop ring resonator feeding element and a T-shaped radiating element. The utilization of the open-loop ring resonator not only reduces [...] Read more.
This paper presents a dual-band four-element multiple-input-multiple-output (MIMO) array for the fifth generation (5G) mobile communication. The proposed antenna is composed of an open-loop ring resonator feeding element and a T-shaped radiating element. The utilization of the open-loop ring resonator not only reduces the size of the antenna element, but also provides positive cross-coupling. The dimension of a single antenna element is 14.9 mm × 7 mm (0.27λ × 0.13λ, where λ is the wavelength of 5.5 GHz). The MIMO antenna exhibits a dual-band feature from 3.3 to 3.84 GHz and 4.61 to 5.91 GHz, which can cover 5G New Radio N78 (3.3–3.8 GHz), 5G China Band N79 (4.8–5 GHz), and IEEE 802.11 ac (5.15–5.35 GHz, 5.725–5.85 GHz). The measured total efficiency and isolation are better than 70% and 15 dB, respectively. The calculated envelope correlation coefficient (ECC) is less than 0.02. The measured results are in good agreement with the simulated results. Full article
(This article belongs to the Special Issue Miniaturized Microwave Components and Devices)
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45 pages, 19519 KiB  
Review
Ultrawideband Antennas: Growth and Evolution
by Om Prakash Kumar, Pramod Kumar, Tanweer Ali, Pradeep Kumar and Shweta Vincent
Micromachines 2022, 13(1), 60; https://doi.org/10.3390/mi13010060 - 30 Dec 2021
Cited by 36 | Viewed by 3383
Abstract
Narrowband antennas fail to radiate short pulses of nano- or picosecond length over the broader band of frequencies. Therefore, Ultrawideband (UWB) technology has gained momentum over the past couple of years as it utilizes a wide range of frequencies, typically between 3.1–10.6 GHz. [...] Read more.
Narrowband antennas fail to radiate short pulses of nano- or picosecond length over the broader band of frequencies. Therefore, Ultrawideband (UWB) technology has gained momentum over the past couple of years as it utilizes a wide range of frequencies, typically between 3.1–10.6 GHz. UWB antennas have been utilized for various applications such as ground-penetrating radars, disaster management through detection of unexploded mines, medical diagnostics, and commercial applications ranging from USB dongles to detection of cracks in highways and bridges. In the first section of the manuscript, UWB technology is detailed with its importance for future wireless communications systems. In the next section various types of UWB antennas and their design methodology are reviewed, and their important characteristics are highlighted. In section four the concept of a UWB notch antenna is presented. Here various methods to obtain the notch, such as slots, parasitic resonators, metamaterials, and filters are discussed in detail. In addition, various types of important notch antenna design with their technical specifications, advantages, and disadvantages are presented. Finally, the need of reconfigurable UWB notch antennas is discussed in the next section. Here various insight to the design of frequency reconfigurable notch antennas is discussed and presented. Overall, this article aims to showcase the beginnings of UWB technology, the reason for the emergence of notching in specific frequency bands, and ultimately the need for reconfiguring UWB antennas along with their usage. Full article
(This article belongs to the Special Issue Miniaturized Microwave Components and Devices)
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