Compact and Passive Thin-Film Frequency Selective Limiters for Resilient Antijamming GPS Receivers

Magnetic materials naturally demonstrate a non-linear power response, thus making them promising candidates for implementing frequency selective limiters (FSLs). Extensive efforts, including the current DARPA CM3IC program, have been carried out to use ferromagnetic insulators for non-linear signal processing. However, the demonstrated FSLs use bulk YIG ceramics with very large ferromagnetic resonance linewidth in the range of 10~100 Oe and high volume in the range of 10~1000mm3 [as reported in the DARPA CM3IC Report, GomacTech Conference 2019, Albuquerque, NM], which lead a very high power rejection signal thresholds, typically 0.1 ~ 10mW, or -10dBm ~ 10dBm for broadband and -25dBm for narrowband, which severely limits their applicability. GPS operates at much lower power range (-120dBm), which requires FSLs with a much lower signal threshold, down to -90dBm for effective protection of the receiver circuit. None of the states of the art FSLs will be useful for such jamming signals with a power range of -90 ~ -10dBm. New TF-FSLs with a low power threshold of -90dBm are needed to protect receivers against any jammer power levels. In this project, Winchester Tehnologies, LLC works closely with subcontractor Northeastern University to achievie the following project goals, which are to: (1) develop a non-linear anti-jamming element termed as thin-film frequency selective limiter (TF-FSL) with an ultra-thin (5~500nm) epitaxial yttrium iron garnet (YIG) film with a low Gilbert damping. The TF-FSL is passive with ultra-low SWAP-C, which is an easy “plug-in” anti-jamming solution for GPS receivers inserted between the antenna and the RF circuit of the receiver; (2) demonstrate resilient anti-jamming GPS receivers in lab and in complex electromagnetic environments with intentional jamming signals. The TF-FSL does not require any reprogramming of the receiver DSP, or modification of the receiver antenna, or add any additional power consumption. The innovation of this project includes the development of novel thin-film frequency selective limiters (TF-FSLs) for resilient anti-jamming GPS receivers with -90dBm power rejection threshold (PRT), thus allowing resilient GPS receivers to handle any jammer. The record-low ferromagnetic resonance linewidth enables the TF-FSL in 5~500nm thick epitaxial yttrium iron garnet (YIG) films, which has been demonstrated by PI Sun and collaborators. The TF-FSL is an element used in the GPS RF front end between the antenna and RFIC, which does not require any reprogramming of the receiver digital signal processor  (DSP), or modification of the receiver antenna, does not add any additional power consumption and constitutes a very small increment in the weight and cost of the receiver. The proposed TF-FSL will provide an ultra-low power rejection threshold (PRT) of -90 dBm (80~100 dB better than state of the art), and >80dB receiver dynamic range, low insertion loss, large bandwidth, and excellent frequency selectivity.