Design and prototype development of motion and shock sensing rf tags.
Akbar, Muhammad Bashir
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Since the inception of the backscatter-radio technology, this field has continually evolved. As a result, this technology is used for a multitude of applications like personnel identification, logistics and assets management and military purposes etc. Radio Frequency Identification (RFID) technology works in several ISM-frequency bands. This work pertains to the design and development of an RF tag that uses 5.8 GHz ISM band for backscatter. This frequency band has many inherent advantages like higher gain antennas, smaller sized tags, increased immunity to conductive object losses, and larger RF bandwidth. The objective of this research is design and prototype development of an RF tag capable of sensing acceleration, angular motion, and shock experienced by an object on which it is installed. The sensed information is modulated onto an incident continuous wave (CW) and backscattered to the reader. Literature research suggested that such work has not been done previously using an RFID platform. The challenges include integration of the sensor, antenna and other electronics to efficiently backscatter the information to the receiver, designing a suitable planar antenna, realtime backscattering of the sensed information, and low power consumption. As a further step, it is required to design and integrate two antennas on RF tag to simultaneously backscatter the same information; and to measure and compare its effect with single antenna tag. The sensed impact/shock and rotational movement information from the inertial sensors (accelerometer and gyroscope) was backscattered instantly and displayed on the custom developed graphical user interface. The development of GUI was not part of this project and was developed by another lab member. RF Tags with single and dual antenna configurations were designed and tested. It was observed that by increasing the number of antennas higher read range can be achieved. Moreover, by doubling the antennas the radar cross-section for the tag was approximately doubled.