J Sabu

Bio: J Sabu is an academic researcher. The author has contributed to research in topics: Folded inverted conformal antenna & Antenna tuner. The author has an hindex of 1, co-authored 1 publications receiving 30 citations.

Circular microstrip patch antenna strain sensor for wireless structural health monitoring

Abstract: In this paper the feasibility of using a circular microstrip patch antenna to detect strain has been investigated. The theoretical model shows a linear relationship between strain and the shift in the resonant frequency of the antenna. A circular patch antenna has been designed and fabricated to work at 1.5GHz. Both Finite Element Analysis (FEA) and experimental tests have been undertaken to corroborate the relationship between strain and frequency shift. The ultimate intention of this work is to configure antennas or resonators for the detection of relatively small damage zones in structures and to do so wirelessly.

Wind Turbine Condition Monitoring: State-of-the-Art Review, New Trends, and Future Challenges

Abstract: As the demand for wind energy continues to grow at exponential rates, reducing operation and maintenance (OM) costs and improving reliability have become top priorities in wind turbine (WT) maintenance strategies. In addition to the development of more highly evolved WT designs intended to improve availability, the application of reliable and cost-effective condition-monitoring (CM) techniques offers an efficient approach to achieve this goal. This paper provides a general review and classification of wind turbine condition monitoring (WTCM) methods and techniques with a focus on trends and future challenges. After highlighting the relevant CM, diagnosis, and maintenance analysis, this work outlines the relationship between these concepts and related theories, and examines new trends and future challenges in the WTCM industry. Interesting insights from this research are used to point out strengths and weaknesses in today’s WTCM industry and define research priorities needed for the industry to meet the challenges in wind industry technological evolution and market growth.

Passive RFID Strain-Sensor Based on Meander-Line Antennas

Abstract: The processing of backscattered signals coming from RFID tags is potentially useful to detect the physical state of the tagged object. It is here shown how to design a completely passive UHF RFID sensor for strain monitoring starting from a flexible meander-line dipole whose shape factor and feed section are engineered to achieve the desired sensing resolution and dynamic range. This class of devices is low-cost, promises sub-millimeter resolution and may found interesting applications in the Structural Health Monitoring of damaged structures and vehicles as well as during extreme and adverse events.

Testing system with electrically coupled and wirelessly coupled probes

Abstract: Conductive electronic device structures such as a conductive housing member that forms part of an antenna may be tested during manufacturing. A test system may be provided that has a pair of pins or other contacts. Test equipment such as a network analyzer may provide radio-frequency test signals in a range of frequencies. The radio-frequency test signals may be applied to the conductive housing member or other conductive structures under test using the test probe contacts. An antenna may be used to gather corresponding wireless radio-frequency signal data. Forward transfer coefficient data may be computed from the transmitted and received radio-frequency signals. The forward transfer coefficient data or other test data may be compared to reference data to determine whether the conductive electronic device structures contain a fault.

Non-contact test system for determining whether electronic device structures contain manufacturing faults

Abstract: Electronic device structures such as structures containing antennas, connectors, welds, electronic device components, conductive housing structures, and other structures can be tested for faults using a non-contact test system. The test system may include a vector network analyzer or other test unit that generates radio-frequency tests signals in a range of frequencies. The radio-frequency test signals may be transmitted to electronic device structures under test using an antenna probe that has one or more test antennas. The antenna probe may receive corresponding radio-frequency signals. The transmitted and received radio-frequency test signals may be analyzed to determine whether the electronic device structures under test contain a fault.

A Review of Passive Wireless Sensors for Structural Health Monitoring

Abstract: Wireless sensors for Structural Health Monitoring (SHM) is an emerging new technology that promises to overcome many disadvantages pertinent to conventional, wired sensors. The broad field of SHM has experienced significant growth over the past two decades, with several notable developments in the area of sensors such as piezoelectric sensors and optical fibre sensors. Although significant improvements have been made on damage monitoring techniques using these smart sensors, wiring remains a significant challenge to the practical implementation of these technologies. Wireless SHM has recently attracted the attention of researchers towards un-powered and more effective passive wireless sensors. This article presents a review of some of the underlying technologies in the field of wireless sensors for SHM - with a focus on the research progress towards the development of simple, powerless, yet effective and robust wireless damage detection sensors. This review examines the development of passive wireless sensors in two different categories: (1) use of oscillating circuits with the help of inductors, capacitors and resistors for damage detection; and (2) use of antennas, Radio Frequency Identification (RFID) tags and metamaterial resonators as strain sensors for wireless damage monitoring. An assessment of these electromagnetic techniques is presented and the key issues involved in their respective design configurations are discussed.