Past Research Projects
Wideband Acoustic Microwave/Millimeter Wave Filters with Extracted Pole Synthesis
This project aims at enhancing microwave/millimeter wave filter performances that incorporate bulk or surface acoustic wave resonators (BAW/SAW). There are two main goals to accomplish in that sense, which correspond to the main limitations of acoustic filters: The first is to increase the achievable bandwidth beyond the level limited by the keff2 value. The passband flatness should be preserved during that operation. The second objective is to achieve strong out-of-band rejection performance. Both aims should be accomplished while preserving prescribed Chebyshev responses with specific ripple and insertion loss values. Extracted pole synthesis and coupling matrix generation techniques are used for designing the filters.
Embedding Filters in Phased Array Antenna Elements for Analog Interference Mitigation
This project aims to integrate filters into the antenna elements of phased array radar systems to provide electronic rejection for interfering signals. The primary goal is to protect the system from strong out-of-band signals by replacing the existing feedline network with miniaturized filters using the same real estate and with minimal impact on the system dynamic range. Additionally, the use of reconfigurable filters is being investigated for in-band interference rejection.
Space-borne Antennas & Circuits for Condensed Radars and STEM (SPACERS)
The goal of the SPACERS project is to support the space exploration mission of NASA through technology development related to a space-borne version of NASA’s EcoSAR. The specific tasks consist of developing T/R modules, innovative circuits for space-borne antennas, and optimized radar waveforms. The project will include flight experiments and terrestrial data collection. Additionally, educational outreach is a big part of the effort, which is being tackled by reaching out to K12 teachers and providing them with added knowledge and tools to promote science.
Reconfigurable, High-Frequency Circuit Components using Phase Change Materials
The purpose of this research project is to develop new, innovative, electronically-tunable substrate materials. These materials will enable frequency and loss tuning of resonating elements that can be used to realize agile radio frequency hardware for future generations of communications and radar systems. The phase change material being used in this work is GeSbTe, which is grown using Pulsed Electron-beam Deposition (PED).
3D Printing of Functional Electromagnetic Structures
Various building methods are being investigated for building complex 3D structures for high-performance, high-frequency parts, such as waveguides, filters, and antennas. These methods include: stereolithography, fused deposition modeling, and selective lasers sintering. This project includes build material characterization at high frequencies.
Frequency-Agile Microwave Filters for Radars with Concurrent Transmission and Reception
The purpose of this project is to develop a pair filter cascades, synchronously controlled for simultaneous transmit and receive (STAR). Investigation of the fundamental limitations with respect to frequency tuning, losses, control mechanisms, and power handling will result in design methodology for a wider range of tunable filter applications.
A closed-loop feedback control method was developed where a capacitive sensor was used to detect the change in the filter tuning mechanism and apply the appropriate voltage corrections to maintain a desired, target frequency. More details on this feedback control can be found in our IMAPS 2014 paper.
Efficient C-Band Power Amplifiers for Airborne Telemetry
In this project, high-efficient power amplifiers are being developed in C-band, intended for airborne telemetry. The amplifiers are realized using Gallium Nitride (GaN) transistors from CREE with customized matching networks in a continuous class F configuration in order to achieve greater than 70% power added efficiency.