EARS: Development of tunable frequency selective limiters based on novel magnetic nanomaterials for RFI mitigation in a crowded spectrum environment

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The tremendous demand on the radio spectrum has come as the consequence of breakthroughs in the applications of wireless technology over the past 20 years. Accessibility to the radio spectrum has become a necessity in the 21st century for commercial as well as for scientific applications. It is the first time in the history of humankind that not only professionals depend on radio frequency (RF) signals and systems, but also people in their daily lives for accessing emails, surfing the web, making travel reservations, "skyping" their friends, tele-navigating while on the road, communicating with home sensors and security systems, and sharing social events. With ever increasing demand for the RF spectrum, the spectrum is becoming more and more crowded with increased level of RF interference among the various systems and applications. Concurrently, we still depend heavily on remote sensing systems for aerially exploring our planet, monitoring environmental changes and their impact on our lives, as well as weather prediction and early warning of natural disasters. These remote sensing systems, which typically try to receive and detect weak RF signals, are vulnerable to deliberate RF interference or even random RF sources including commercial communication systems. Mitigation of unwanted RF signals is becoming of utmost importance in modern wireless systems for both remote sensing and commercial wireless communication applications. Enhancing access to the existing RF spectrum will not be possible without addressing the RF interference issue, especially since demand on the bandwidth of RF systems is growing rapidly and RF receivers are becoming more sensitive.This project will address the RF interference issue by focusing on the development of composite magnetic nanomaterials that can be deposited as thin films on a variety of substrates and provide a tunable RF signal rejection device called a Frequency Selective Limiter (FSL). This device will significantly attenuate any signal above a specific power level at a given frequency which is close to the operational band of the system to be protected. Thus, the FSL acts as a self-adapting filter depending on the strength of the interference. A fundamental understanding on the interaction and relationship between material composition and RF response (rejection frequency, rejection level, rejection bandwidth, DC magnetic field bias) will be pursued in order to tailor the FSL for rejecting a targeted RF interference in any remote sensing or wireless communication application. An important objective is to achieve compact and planar RF devices with such performance in the 1-20 GHz range for integration in System-on-Chip (SoC) or System-on-Package (SoP) RF front ends. To do so, the following objectives will be pursued: (1) understand how to control the Ferromagnetic Resonance (FMR) of the nanomagnetic materials; (2) understand how to control the rejection bandwidth and threshold power level; (3) understand the effect of the DC bias field strength and direction; and (4) demonstrate the feasibility of robust, planar RFI rejection devices by creating planar RF circuits with magnetic nanomaterials that exhibit the response of an FSL in the 1-20 GHz range. This topic also lends itself to exposing students to nanotechnology and RF hardware technology that so many of them use today. Undergraduate students from underrepresented groups will be recruited in this project to participate in various research training and outreach programs.