scholarly journals Liquid-Based Reconfigurable Antenna Technology: Recent Developments, Challenges and Future

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 827
Author(s):  
Habshah Abu Bakar ◽  
Rosemizi Abd Rahim ◽  
Ping Jack Soh ◽  
Prayoot Akkaraekthalin
Keyword(s):  
High Frequency ◽  
Communication Systems ◽  
Room Temperature ◽  
State Of The Art ◽  
Reconfigurable Antennas ◽  
Wireless Communication Systems ◽  
Dielectric Resonators ◽  
Different Types ◽  
Recent Developments ◽  
Basic Approaches

Advances in reconfigurable liquid-based reconfigurable antennas are enabling new possibilities to fulfil the requirements of more advanced wireless communication systems. In this review, a comparative analysis of various state-of-the-art concepts and techniques for designing reconfigurable antennas using liquid is presented. First, the electrical properties of different liquids at room temperature commonly used in reconfigurable antennas are identified. This is followed by a discussion of various liquid actuation techniques in enabling high frequency reconfigurability. Next, the liquid-based reconfigurable antennas in literature used to achieve the different types of reconfiguration will be critically reviewed. These include frequency-, polarization-, radiation pattern-, and compound reconfigurability. The current concepts of liquid-based reconfigurable antennas can be classified broadly into three basic approaches: altering the physical (and electrical) dimensions of antennas using liquid; applying liquid-based sections as reactive loads; implementation of liquids as dielectric resonators. Each concept and their design approaches will be examined, outlining their benefits, limitations, and possible future improvements.

scholarly journals Liquid-Based Reconfigurable Antenna Technology: Recent Developments, Challenges and Future

2020 ◽  
Author(s):  
Habshah Abu Bakar ◽  
Rosemizi Abd Rahim ◽  
Ping Jack Soh ◽  
Prayoot Akkaraekthalin
Keyword(s):  
High Frequency ◽  
Communication Systems ◽  
Room Temperature ◽  
State Of The Art ◽  
Reconfigurable Antennas ◽  
Wireless Communication Systems ◽  
Dielectric Resonators ◽  
Different Types ◽  
Recent Developments ◽  
Basic Approaches

Advances in reconfigurable liquid-based reconfigurable antennas are enabling new possibilities to fulfil the requirements of more advanced wireless communication systems. In this review, a comparative analysis of various state-of-the-art concepts and techniques for designing reconfigurable antennas using liquid is presented. First, the electrical properties of different liquids at room temperature commonly used in reconfigurable antennas are identified. This is followed by a discussion of various liquid actuation techniques in enabling high frequency reconfigurability. Next, liquid-based reconfigurable antennas in literature used to achieve the different types of reconfiguration will be critically reviewed. These include frequency-, polarization-, radiation pattern- and compound reconfigurability. The current concepts of liquid-based reconfigurable antennas can be classified broadly into three basic approaches: altering the physical (and electrical) dimensions of antennas using liquid, applying liquid-based sections as reactive loads; and implementation of liquids as dielectric resonators. Each concept and their design approaches will be examined, outlining their benefits, limitations, and possible future improvements.

Methods for improving the accuracy of frequency shift estimation in 5G NR

2021 ◽  
Author(s):  
Vladimir Sergeevich Milyutin ◽  
Eugeniy Vasilevich Rogozhnikov ◽  
Kirill Petrovskiy ◽  
Dmitriy Pokamestov ◽  
Edgar Dmitriyev ◽  
...  
Keyword(s):  
Frequency Shift ◽  
High Frequency ◽  
Communication Systems ◽  
Wide Frequency Range ◽  
Wireless Communication Systems ◽  
Frequency Synchronization ◽  
Frequency Range ◽  
Transmission Rates ◽  
Synchronization Accuracy ◽  
High Order Modulation

Abstract Frequency synchronization is a necessary operation for all wireless communication systems. Due to the wide frequency range defined for 5G NR systems, this procedure becomes critical. To ensure high transmission rates and the use of high-order modulation, up to 256 QAM for 5G communication systems, it is necessary to ensure high frequency synchronization accuracy. In this article, we have reviewed various approaches to implementing frequency synchronization and proposed, in our opinion, the most effective method for correcting the frequency shift of the signal.

Reconfigurable Antenna

2016 ◽  
pp. 237-263
Author(s):  
Mohamad Kamal A Rahim ◽  
Huda A. A. Majid ◽  
Mohamad Rijal Hamid
Keyword(s):  
Communication Systems ◽  
Low Cost ◽  
Wireless Systems ◽  
Reconfigurable Antennas ◽  
Effective Length ◽  
Slot Antenna ◽  
Wireless Communication Systems ◽  
Reconfigurable Antenna ◽  
5 Ghz ◽  
Narrow Bands

Reconfigurable antennas have attracted a lot of attention especially in future wireless communication systems. Superior features such as reconfigurable capability, low cost, multi-purpose functions and size miniaturization have given reconfigurable antennas advantage to be integrated into a wireless systems. In this chapter, two types of reconfigurable antennas are discussed. First, frequency reconfigurable narrowband microstrip slot antenna (FRSA) is presented. The proposed antenna is designed to operate at six reconfigurable frequency bands from 2 GHz to 5 GHz with bidirectional radiation pattern. The second antenna design is frequency reconfigurable narrowband patch-slot antenna (FRPSA) is presented. The antenna is a combination of a microstrip patch and slot antenna. Nine different narrow bands are produced by tuning the effective length of the slot. The performances of the antenna in term of simulated and measured results are presented. In conclusion, good agreement between the simulated and measured results has been attained.

scholarly journals Direct Transmission of Digital Message via Programmable Coding Metasurface

Research ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Tie Jun Cui ◽  
Shuo Liu ◽  
Guo Dong Bai ◽  
Qian Ma
Keyword(s):  
Wireless Communications ◽  
High Frequency ◽  
Communication Systems ◽  
Wireless Communication Systems ◽  
Digital Information ◽  
Direct Transmission ◽  
The Past ◽  
Multiple Receivers ◽  
High Frequency Microwave ◽  
Passive Microwave Devices

In modern wireless communications, digital information is firstly converted to analog signal by a digital-analog convertor, which is then mixed to high-frequency microwave to be transmitted through a series of devices including modulator, mixer, amplifier, filter, and antenna and is finally received by terminals via a reversed process. Although the wireless communication systems have evolved significantly over the past thirty years, the basic architecture has not been challenged. Here, we propose a method to transmit digital information directly via programmable coding metasurface. Since the coding metasurface is composed of ‘0’ and ‘1’ digital units with opposite phase responses, the digital information can be directly modulated to the metasurface with certain coding sequences and sent to space under the illumination of feeding antenna. The information, being modulated in radiation patterns of the metasurface, can be correctly received by multiple receivers distributed in different locations. This method provides a completely new architecture for wireless communications without using complicated digital-analog convertor and a series of active/passive microwave devices. We build up a prototype to validate the new architecture experimentally, which may find promising applications where information security is highly demanded.

scholarly journals Machine Learning in Beyond 5G/6G Networks—State-of-the-Art and Future Trends

Electronics ◽  
2021 ◽  
Vol 10 (22) ◽  
pp. 2786
Author(s):  
Vasileios P. Rekkas ◽  
Sotirios Sotiroudis ◽  
Panagiotis Sarigiannidis ◽  
Shaohua Wan ◽  
George K. Karagiannidis ◽  
...  
Keyword(s):  
Artificial Intelligence ◽  
Machine Learning ◽  
Wireless Communications ◽  
Wireless Communication ◽  
Communication Systems ◽  
State Of The Art ◽  
Wireless Communication Systems ◽  
Future Trends ◽  
Network Applications ◽  
Open Issues

Artificial Intelligence (AI) and especially Machine Learning (ML) can play a very important role in realizing and optimizing 6G network applications. In this paper, we present a brief summary of ML methods, as well as an up-to-date review of ML approaches in 6G wireless communication systems. These methods include supervised, unsupervised and reinforcement techniques. Additionally, we discuss open issues in the field of ML for 6G networks and wireless communications in general, as well as some potential future trends to motivate further research into this area.

Biological or Chemico-Physical Landfill Leachate Purification - An Alternative or a Useful Combination

1992 ◽  
Vol 26 (1-2) ◽  
pp. 137-145 ◽  
Author(s):  
J. T. Kettern
Keyword(s):  
Landfill Leachate ◽  
State Of The Art ◽  
Engineering Practice ◽  
Treatment Technology ◽  
Leachate Treatment ◽  
Different Types ◽  
Recent Developments ◽  
Minimum Requirements

The passing of the “General Administrative Regulations on Minimum Requirements for the Discharge of Sewage to Waters”, and particularly Annex 51, has far-reaching implications for landfill leachate treatment. The administrative regulations prescribe limits which entail treatment according to good engineering practice and state-of-the-art technology. The paper describes leachates from different types of landfill, discusses state-of-the-art leachate treatment technology and presents some recent developments.

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