Recent Progress on Development of Near-Field Structures for Radio-Frequency Front-End Antennas

This paper investigates the challenges of developing a multi-frequency radio frequency interference (RFI) monitoring and characterization system that is optimized for ease of deployment and operation as well as low per unit cost. To achieve this, we explore the design and development of a multiband global navigation satellite system (GNSS) front-end which is intrinsically capable of synchronizing side channel information from non-RF sensors, such as inertial measurement units and integrated power meters, to allow the simultaneous production of substantial amounts of sampled spectrum while also allowing low-cost, real-time monitoring and logging of detected RFI events. While the inertial measurement unit and barometer are not used in the RFI investigation discussed, the design features that provide for their precise synchronization with the RF sample stream are presented as design elements worth consideration. The designed system, referred to as Four Independent Tuners with Data-packing (FITWD), was utilized in a data collection campaign over multiple European and Scandinavian countries in support of the determination of the relative occurrence rates of L1/E1 and L5/E5a interference events and intensities where it proved itself a successful alternative to larger and more expensive commercial solutions. The dual conclusions reached were that it was possible to develop a compact low-cost, multi-channel radio frequency (RF) front-end that implicitly supported external data source synchronization, and that such monitoring systems or similar capabilities integrated within receivers are likely to be needed in the future due to the increasing occurrence rates of GNSS RFI events.

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Uses of radio emission spectroscopy for non-contact and in situ diagnostics of low pressure radio frequency plasma processing

10.21203/rs.3.rs-678053/v1 ◽

2021 ◽

Author(s):

Rajani K. Vijayaraghavan ◽

Sean Kelly ◽

David Coates ◽

Cezar Gaman ◽

Niall MacGearailt ◽

...

Keyword(s):

Radio Emission ◽

Radio Frequency ◽

Emission Spectroscopy ◽

Near Field ◽

Plasma Processing ◽

Diagnostic Technique ◽

Primary Source ◽

Low Pressure ◽

Chamber Pressure ◽

Rf Plasma

Abstract We demonstrate that a passive non-contact diagnostic technique, radio emission spectroscopy (RES), provides a sensitive monitor of currents in a low pressure radio frequency (RF) plasma. A near field magnetic loop antenna was used to capture RF emissions from the plasma without perturbing it. The analysis was implemented for a capacitively coupled RF plasma with an RF supply at a frequency of 13.56 MHz. Real-time measurements are captured in scenarios relevant to contemporary challenges faced during semiconductor fabrication (e.g. window coating and wall disturbance). Exploration of the technique for key equipment parameters including applied RF power, chamber pressure, RF bias frequencies and chamber wall cleanliness shows sensitive and repeatable function. In particular, the induced RES signal was found to vary sensitively to pressure changes and we were able to detect pressure and power variations as low as ~2.5 %/mtorr and ~3.5 %/watt, respectively, during the plasma processing during a trial generic plasma process. Finally, we explored the ability of RES to monitor the operation of a multiple frequency low-pressure RF plasma system (f1 = 2 MHz, f2 = 162 MHz) and intermixing products which suggests strongly that the plasma sheaths are the primary source of this non-linear diode mixing effect.

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Design and Development Of Lecturer Attendance System Using Radio Frequency Identification (RFID)

International Journal of Computer Science Engineering ◽

10.21817/ijcsenet/2021/v10i1/211001010 ◽

2021 ◽

Vol 10 (1) ◽

pp. 15-27

Author(s):

I Gede Sujana Eka Putra ◽

Anthony Lee ◽

I Made Tirta Mahayana ◽

I Gede Agung Wicaksono Dharmayasa

Keyword(s):

Radio Frequency ◽

Radio Frequency Identification ◽

Web Application ◽

Academic Staff ◽

Near Field ◽

Literature Study ◽

Master Data ◽

Presence Data ◽

Frequency Identification ◽

The University

Lecturer attendance record is required by the university to know the presence of lecturers in teaching in class. In general condition, lecturer attendance is recorded on the attendance sheet, or input to web application accessed on a class computer. However, there are some problems in its implementation so that at the end, lecturer presence is carried out using a manual form where the academic staff needs to re-enter the lecturer attendance data into the applications. Based on the above, the authors designed and developed a lecturer attendance information system to record lecturers' attendance using radio frequency identification technology by implementing a near field communication card (NFC Card). The device used to record and read presence data during lectures, by tapping an Mi-fare NFC card to an NFC reader / writer device. The flow of this research method begins with a literature study of NFC card, observe the flow of lecture attendance process and data recorded into lecturer attendance sheet, analyzing the database design, the system design which has compatible with NFC reader and writer devices, designed system interface and continue to develop system. The result is system consists of master data, system attendance, verification and reporting module. The results show that NFC card implementation is more practical for lecturers in conducting lecture attendance and NFC card could be tapped out into an NFC device at a maximum distance up to 7 cm with the reading angle relative to NFC reader/writer with range 00 until 300 can read NFC Card.

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Adjustable Radio Frequency Front End Receiver for SDR and CR Applications Employing Noise Cancelling

2019 IEEE 62nd International Midwest Symposium on Circuits and Systems (MWSCAS) ◽

10.1109/mwscas.2019.8884957 ◽

2019 ◽

Author(s):

Ahmed Hussein Ahmed AbdelRahman ◽

Mohamed El-Nozahi ◽

Hani Fikry Ragai

Keyword(s):

Radio Frequency ◽

Front End ◽

Noise Cancelling

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High precision epidermal radio frequency antenna via nanofiber network for wireless stretchable multifunction electronics

Nature Communications ◽

10.1038/s41467-020-19367-8 ◽

2020 ◽

Vol 11 (1) ◽

Author(s):

Yufei Zhang ◽

Zhihao Huo ◽

Xiandi Wang ◽

Xun Han ◽

Wenqiang Wu ◽

...

Keyword(s):

Radio Frequency ◽

Near Field ◽

Transmission Efficiency ◽

Stretchable Electronics ◽

Information Communication ◽

Long Distance ◽

Human Machine Interaction ◽

Natural Systems ◽

Content Recognition ◽

Healthcare Monitoring

Abstract Recently, stretchable electronics combined with wireless technology have been crucial for realizing efficient human-machine interaction. Here, we demonstrate highly stretchable transparent wireless electronics composed of Ag nanofibers coils and functional electronic components for power transfer and information communication. Inspired by natural systems, various patterned Ag nanofibers electrodes with a net structure are fabricated via using lithography and wet etching. The device design is optimized by analyzing the quality factor and radio frequency properties of the coil, considering the effects of strain. Particularly, the wireless transmission efficiency of a five-turn coil drops by approximately only 50% at 10 MHz with the strain of 100%. Moreover, various complex functional wireless electronics are developed using near-field communication and frequency modulation technology for applications in content recognition and long-distance transmission (>1 m), respectively. In summary, the proposed device has considerable potential for applications in artificial electronic skins, human healthcare monitoring and soft robotics.

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A Baseband Wireless Spectrum Hypervisor for Multiplexing Concurrent OFDM Signals

Sensors ◽

10.3390/s20041101 ◽

2020 ◽

Vol 20 (4) ◽

pp. 1101

Author(s):

Felipe A. P. de Figueiredo ◽

Ruben Mennes ◽

Irfan Jabandžić ◽

Xianjun Jiao ◽

Ingrid Moerman

Keyword(s):

Radio Frequency ◽

Mobile Networks ◽

Spectral Efficiency ◽

Base Stations ◽

Traffic Load ◽

Front End ◽

Rf Front End ◽

Radio Access ◽

Wireless Spectrum ◽

Arbitrary Frequency

The next generation of wireless and mobile networks will have to handle a significant increase in traffic load compared to the current ones. This situation calls for novel ways to increase the spectral efficiency. Therefore, in this paper, we propose a wireless spectrum hypervisor architecture that abstracts a radio frequency (RF) front-end into a configurable number of virtual RF front ends. The proposed architecture has the ability to enable flexible spectrum access in existing wireless and mobile networks, which is a challenging task due to the limited spectrum programmability, i.e., the capability a system has to change the spectral properties of a given signal to fit an arbitrary frequency allocation. The proposed architecture is a non-intrusive and highly optimized wireless hypervisor that multiplexes the signals of several different and concurrent multi-carrier-based radio access technologies with numerologies that are multiple integers of one another, which are also referred in our work as radio access technologies with correlated numerology. For example, the proposed architecture can multiplex the signals of several Wi-Fi access points, several LTE base stations, several WiMAX base stations, etc. As it able to multiplex the signals of radio access technologies with correlated numerology, it can, for instance, multiplex the signals of LTE, 5G-NR and NB-IoT base stations. It abstracts a radio frequency front-end into a configurable number of virtual RF front ends, making it possible for such different technologies to share the same RF front-end and consequently reduce the costs and increasing the spectral efficiency by employing densification, once several networks share the same infrastructure or by dynamically accessing free chunks of spectrum. Therefore, the main goal of the proposed approach is to improve spectral efficiency by efficiently using vacant gaps in congested spectrum bandwidths or adopting network densification through infrastructure sharing. We demonstrate mathematically how our proposed approach works and present several simulation results proving its functionality and efficiency. Additionally, we designed and implemented an open-source and free proof of concept prototype of the proposed architecture, which can be used by researchers and developers to run experiments or extend the concept to other applications. We present several experimental results used to validate the proposed prototype. We demonstrate that the prototype can easily handle up to 12 concurrent physical layers.

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On the nature of the microwave field emerging from a composite pupil

Modern Physics Letters B ◽

10.1142/s0217984920502474 ◽

2020 ◽

Vol 34 (24) ◽

pp. 2050247

Author(s):

Ilaria Cacciari ◽

Daniela Mugnai ◽

Anedio Ranfagni

Keyword(s):

Wave Propagation ◽

Stochastic Model ◽

Radio Frequency ◽

Delay Time ◽

Microwave Field ◽

Near Field ◽

Phase Variation ◽

Experimental Investigations ◽

Frequency Signal ◽

Made In

Further experimental investigations in the microwave field emerging from a composite pupil are reported in order to determine the nature of the wave propagation. The experiments consisted of delay-time measurements as a function of the distance of the detector from the pupil under test, as well as of the phase variation of a radio-frequency signal at 35 MHz that modulated the same microwave carrier at 9.33 GHz. In addition, measurements employing an admittance comparator were made in order to determine the character of the propagation impedance. All results obtained confirmed superluminal behavior in the near field, up to a distance of about 40 cm. These results were then interpreted within the framework of a stochastic model.

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