Sushim Mukul Roy

Quasi-static modeling of defected ground structure

A quasi-static equivalent-circuit model of a dumbbell-shaped defected ground structure is developed. The equivalent-circuit model is derived from the equivalent inductance and capacitance developed due to the perturbed return current path on the ground and the narrow gap, respectively. The theory is validated against the commercial full-wave solver CST Microwave Studio. Finally, the calculated results are compared with the measured results. Good agreement between the theory, the commercially available numerical analyses, and the experimental results validates the developed theoretical model.

Development of Smart Antenna for RFID Reader

Radio frequency identification (RFID) systems have many important applications in the 900 MHz frequency band. A 3x2-element planar smart antenna for RFID readers in a low cost compact package is developed. The smart antenna covers 860-960 MHz frequency band with more than 10 dB input return loss, 12 dBi broadside gain and up to 40deg elevation beam scanning with a 4-bit reflection type phase shifter array. Once implemented in the mass market, RFID smart antennas will contribute tremendously in the areas of RFID tag reading rates, collision mitigation, location finding of items and capacity improvement of the RFID system.

Novel N - way Power Divider and Array Configuration for RFID Readers operating at 5.8 GHz

A novel N - way power divider has been designed to be used in arrays for the development of readers in RFID systems. In contrast with the conventional power dividers, this power divider can accommodate any number of power division starting from 1 to 16 and higher from one central circular microstrip patch acting like a hub. Like other conventional power dividers, this power divider can also be put in cascade. The power divider is broadband in nature and greatly reduces space used by arrays compared to the conventional designs. Additionally, the scope of this power divider to be used in RFID systems is huge opening an entire new approach to tracking electronics.

Quasi-Static Analysis of Defected Ground Structure

A quasi-static equivalent circuit model of a dumbbell shaped defected ground structure (DGS) is developed. The equivalent circuit model is derived from the equivalent inductance and capacitance developed due to the perturbed returned current path on the ground and the narrow gap, respectively. The theory is validated against the commercial full-wave solver CST Microwave Studio. Finally, the calculated results are compared with the measured results. Good agreement between the theory, the commercially available numerical analyses and the experimental results validates the developed theoretical model.

Analysis of Different DGS Configurations in Terms of Microstrip Discontinuities

Defected ground structure (DGS) has been analysed in terms of various microstrip discontinuities (quasi static approach). It has been shown that the junction capacitance plays an equally important role in determining the position of attenuation pole of the unit cell DGS as the gap capacitance. Theory is validated against simulation results by commercially available MoM Solver CST design environment. Good agreements between simulated and calculated results validate the theory.

Study of Optical Frequency Multiplication for Radio-Over-Fiber Systems

We have studied and analyzed the optical frequency multiplication or optical harmonic up-conversion of low-frequency microwave signals while optically up-converting their frequencies. We have simulated the relative intensity of the harmonic components of the generated microwave signal for a triangular wavelength sweep. It has observed in the simulation results that with the increase of harmonic components, the relative intensity decreases for the low values of plate reflectivity