The review focuses on the emergence of 5G wireless communication and the need for multiple-input multiple-output antennas to support high-speed communication systems. The article discusses the ...advantages of MIMO antennas, including increased channel capacity and the ability to focus radio frequency energy on specific users. However, the challenges of creating compact MIMO antennas with ideal isolation are addressed, including short wavelengths, connection losses, constrained bandwidth, and path losses in the millimeter-wave range. Design techniques and methods to enhance the performance of conventional antennas for 5G applications are discussed, along with potential solutions for upcoming challenges. The article provides an overview of MIMO antennas for 5G applications, covering frequency bands, system architecture, advantages, challenges, advancements, performance enhancement techniques, design techniques, and state-of-the-art developments.
An approach is presented to enhance the isolation of a two-port Multiple Input Multiple Output (MIMO) antenna using a decoupling structure and a common defected ground structure (DGS) that physically ...separates the antennas from each other. The antenna operates in the 24 to 40 GHz frequency range. The innovation in the presented MIMO antenna design involves the novel integration of two arc-shaped symmetrical elements with dimensions of 35 × 35 × 1.6 mm3 placed perpendicular to each other. The benefits of employing an antenna with elements arranged perpendicularly are exemplified by the enhancement of its overall performance metrics. These elements incorporate a microstrip feed featuring a quarter-wave transformer (QWT). This concept synergizes with decoupling techniques and a defected ground structure to significantly enhance isolation in a millimeter wave (mm wave) MIMO antenna. These methods collectively achieve an impressively wide bandwidth. Efficient decoupling methodologies have been implemented, yielding a notable increase of 5 dB in isolation performance. The antenna exhibits 10 dB impedance matching, with a 15 GHz (46.87%) wide bandwidth, excellent isolation of more than 28 dB, and a desirable gain of 4.6 dB. Antennas have been analyzed to improve their performance in mm wave applications by evaluating diversity parameters such as envelope correlation coefficient (ECC) and diversity gain (DG), with achieved values of 0.0016 and 9.992 dB, respectively. The simulation is conducted using CST software. To validate the findings, experimental investigations have been conducted, affirming the accuracy of the simulations.
Presented work describes the symmetrical quad-element Multiple-Input Multiple-Output (MIMO) antenna operating at 28 GHz for Fifth generation (5G) millimeter-wave (mm-wave) spectrum. The core of this ...antenna system features a stepped-shaped patch radiator precisely tuned to 28 GHz, effectively broadening its resonance across the desired operational frequency band. To improve isolation, an Isolating Metallic Sheet (IMS) is precisely placed between the patch radiators of projected antenna. Rogers RT5880 substrate is used to fabricate with dimensions of 20.48 × 20.48 mm2, thickness of 1.6 mm, and dielectric constant of 2.2. Both simulationand measurement outcomesindicate that the antenna has a bandwidth of 7.13 GHz, covering frequencies ranging from 25.21 GHz to 32.34 GHz, for a fractional bandwidth of 24.78 %. Key antenna performance measurements include a peak amplitude of up to 53 dB and a significant port-to-port isolation of more than 20 dB. Ithasbeen carefully examined revealing a minimum channel capacity loss of 0.135 bits/s/Hz, a mean effectivegain of −3 dB, a diversity gain of around 10 dB, a total active reflection coefficient of −10 dB, and an envelope correlation coefficient of less than 0.005. Presentedantenna meets industrial requirementsfor high-speed mm-wave communications in 28 GHz 5G networks.
A compact MIMO antenna has been designed explicitly for Ka-band for 5G wireless networks. The antenna uses four P-shaped radiating patches in E-shaped slots for polarization variety in the 20-40 GHz ...frequency band. The Rogers RT/duroid 5880 substrate (26 × 25 × 1.6) supports each patch and defective ground for each element. Polarization diversity lowers radiating element interference, making this antenna design advantageous. Therefore, the antenna has a wide bandwidth of 20 GHz. A high isolation level of over -20 dB has been attained by carefully examining the mutual connection between antenna radiators. After a detailed analysis of the radiation patterns, a gain of 17.6 dBi is found. Both total and radiating efficiency exceed 87% and 91%. MIMO system dependability is evaluated by assessing diversity characteristics including ECC, DG, CCL, MEG, and TARC, yielding findings of 0.0035, 9.98 dB, 0.013 bits/sec/Hz, -3 dB, and -10 dB. Simulations and observations show a significant agrement.
This article presents a simple planar millimeter-wave (mm-wave) multiple input multiple output (MIMO) antenna with four closely spaced radiating elements. The antenna is intended to enhance the ...bandwidth for 5G new radio (NR) applications and also cover the industrial Ka-band (26.5-40 GHz), Q-band (30-50 GHz), and U-band (40-60 GHz) frequency ranges. The antenna is designed using Rogers RT/duroid 5880 substrate with a size of 25×26×1.6 mm3. The proposed antenna consists of four identical radiating elements with two of them positioned in a linear configuration facing each other, while the other two elements are placed opposite to the first two, which improves isolation between the elements. Across the entire operating frequency range (26-60 GHz), the antenna demonstrated excellent performance, including 34 GHz wide bandwidth, high isolation of >25 dB, nearly omnidirectional radiation patterns, high gain of 11.1 dB with a high radiation efficiency of 94%, low envelope correlation coefficient (ECC) of 0.0068, and high diversity gain (DG) of 9.967 dB. The simulated findings exhibit a strong positive correlation with the experimental results. The proposed MIMO antenna design is a promising solution for 5G NR applications.
Inductive output tube (IOT) - a review Kaushik, Meenu; Joshi, L.M.
Journal of electromagnetic waves and applications,
10/2015, Volume:
29, Issue:
15
Journal Article
Peer reviewed
This study is all about the evolution of inductive output tube (IOT) and its significance in the current scenario. The historical review with timeline is briefly discussed. The basic design ...considerations and operating principle of IOT have been described. This tube is opted for many applications these days over other conventional vacuum tubes for various advantages. Initially used for television transmitters, this tube is now well recognized for other industrial applications also which are discussed in the study. A comparative review of IOT over other conventional tubes is also given wherever required. The current state of the art of the tube is described to convey the present needs of the device.
The paper reports the theoretical approach and computer-aided design results for a 350 MHz, 100 kW (CW) inductive output tube. The design considerations and methodologies employed for electromagnetic ...simulation of individual electron gun and RF cavity assemblies and that of their combined assembly were presented. The electron gun parameters namely the beam radius, perveance and electrodes dimensions were optimized. The input cavity was designed and the parameters, namely the resonant frequency, radius and length of the cavity with respect to the desired propagating mode were characterized. The combined integrated model demonstrates the RF input cavity placed onto the gun structure. The interaction of electron beam (40 kV, 3.5 A) and applied input RF signal of 400 W produces an RF current of ~ 85 A in the interaction gap (i.e. cathode-grid spacing). The focusing structure of the device necessary for getting the efficient amplification has also been designed and optimized. The simulations presented in the paper are carried out using CST, MAGIC2D and TRAK codes.
In this study, a novel dual-port rectangular patch antenna is presented that provides triple-band operation across three distinct frequency subranges:15.25-15.6THz, 16.3-18.2THz, and 19.03-19. ...7THz.The antenna functions within the frequency range of 15 THz to 20 THz. The findings of the research highlight the antenna's efficient operation of important parameters such as reflection coefficient, VSWR, bandwidth, and gain. Remarkably, the suggested antenna design has many uses. In addition to the previously specified performance metrics, simulated results show that the antenna remains isolated ablest an19dB over the entire operating frequency range, which is additional evidence of its reliable operation and compliance with conventional antenna standards.
This works describes the design of a highly isolated wideband two-element semi-circular shaped patch with rectangular dielectric resonator antenna (RDRA). The antenna is operated at (24GHz - 40 GHz) ...that covers Ka-band (27 GHz -40GHz). Dielectric resonator antenna (DRA) is positioned perpendicular to one another in order to accomplish the desired wide-band functioning with good impedance matching, increased gain, and bandwidth. To improve the isolation between antenna elements, diamond shape slot is etched in the ground plane. The DRA configuration provides a higher gain of approximately 7.8 dB and nearly omnidirectional radiation patterns. In addition, the recommended DRA MIMO performance parameters are examined and reported. The results indicate that the suggested DRA MIMO antenna is considered a suitable contender for 5G millimeter wave-based applications.
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