Research

The thesis focuses on designing RF/Microwave resonators based on capacitive coupling principle that can produce dynamic range of frequency signatures for angular rotation. These resonators are implemented as the sensing element in rotation sensors and in realizing programmable chipless RFID tags with a frequency signature.

The project focussed on designing an angularly stable FSS using round robin structure of split ring resonators that can produce a bandstop response for varying angles of incidence. An improved design by altering the current path is devised. The new design achieves miniaturization and stable angular response for both TE and TM mode incidence.

My responsibilities include performing reviews and investigations of Biomedical Sensors and designing RF and microwave sensors for biomedical applications. The sensing technique employed varies from resonant to broadband.

A crowd counting system was designed using RFID tags and antennas where the crowd need not be tagged. Two algorithms using Neural Network and waveform matching technique were developed and implemented in MATLAB. The system could estimate the number of people crossing the designated path with reasonably good accuracy. It was tested in an indoor environment for a continuously moving crowd of up to 75 persons, and the count estimation with 90% accuracy was achieved.

With the proliferation of item-level tagging using RFID tags, which are usually linearly polarized, an RFID system was used to detect the orientation of the tags and hence that of the object to which the tag is attached. LabVIEW was used to process the tag reads using various filtering techniques on the RSSI data.

SAR was calculated using an 835MHz microstrip patch antenna simulating an RF device using COMSOL. The change in the total SAR in the human head for different orientations of the antenna were studied. It was found that the temperature rise/fall on the surface of the exposed area of the head significantly depends on the angle of rotation of the radiating device. The SAR in simulation results were found to be always below the FCC threshold of 1.6 W/kg.