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Microwave Imaging

We have recently started on ultra wideband subsystems for microwave imaging.  We use our own antenna designs which have very good characteristics for pulse propagation.  Related to this, we are also exploring CRLH based circuits for generation and processing of chirped pulses.

Antennas

·         Fractal Shaped Antennas

·         Wideband Microstrip Antennas

·         Multi-band Microstrip Antennas

·         Micromachined Antennas

Microwave antenna is still a very active area of research. We emphasize on various Fractal and Microstrip antenna configurations. Complete facilities for antenna modeling and characterization are available in the Lab.  We have already acquired a 50GHz vector network analyzer and set up a Microwave Anechoic chamber. 

Our research on fractal shaped elements for antennas focused by corroborating the potential relationships between mathematically quantifiable features such as fractal dimension and lacunarity.  Self-similarity of fractals has been associated with multi-frequency characteristics of antennas.

While the use of fractal geometries for realizing small and multi-frequency antennas are well documented, these are not necessarily the best solutions with practical constraints.  In a pioneering study, this group has achieved the unique possibility of incorporating several single-frequency antennas into a common space for designing multi-frequency antennas.  In order to address the wide bandwidth requirements for modern wireless terminals, this group has recently developed a simple wideband microstrip patch antenna configuration with 50% bandwidth (impedance and gain).  Its modifications for circular polarization, and improved radiation characteristics have also been proposed.

Microwave Circuits

·      RF Power transfer/ Energy harvesting Circuits

·      Ultra Wideband filters

We have developed antennas and circuits for harvesting RF energy.  We have demonstrated that it is possible to build a low power communication terminal operating on such harvested energy. 

We have developed novel ideas on miniaturizing passive components such as filters, phase shifters and resonators.  PCBs to LTCC techniques have been used for their experimental prototypes.

TeraHertz Systems

·         Open ended Diamond Shaped Waveguides

·         Non-linear transmission lines

A potential application of the micro-fabrication technology that has recently gained attention is in the domain of sensing and imaging systems that use terahertz radiation. Terahertz band has a typical frequency range of 100GHz to 10 THz corresponding to a wavelength range of 3mm to 30 um. Due to advantages of this band in strategic, sensor and communication systems, developing micromachined low-cost sensing systems that operate at these frequencies has caught the attention of the scientific community. We have started our work in this area by studying suitable waveguiding systems.  A diamond-shaped waveguide is designed on silicon that can be fabricated with micromachining techniques.  We are presently exploring  fabrication of slow wave structures for TWTs at mm wave bands.  Use of various nanomaterials is also being explred.   

Computational Electromagnetics

With the evolution of micro- and nano fabrication technologies for microwave components and devices, new approaches involving multi-physics are required for their accurate modeling.  Under a new project, a spectral domain approach would be extended for solving coupled Maxwell’s equations for modeling nanocomposites with electromagnetic applications.  We plan to investigate a spectral finite element method for these.

Microwave Materials

·       High impedance surfaces for antennas

Performance improvement of antennas and several other circuit components have been demonstrated by the group.  There are plans to extend these for future 60GHz wireless systems, to investigate issues related to integrating antennas on chip such as design possibilities for reduced arrays, and approaches towards reducing interference to other components on chip.

RF MEMS

·         Phase Shifters

·         Switches

·         Pased Array Antennas

Micromachining techniques are fast becoming the mainstay of millimeter and sub-millimeter wave systems for wireless, military, aerospace and sensor applications. We have established sophisticated RF and microwave modeling capabilities for the analysis, design and characterization of these systems. Collaborative efforts are pursued for the fabrication of such devices.  In addition we have developed a low cost concept for RF MEMS phase shifters for phased array applications.