Magnetostatic Wave Frequency Selective Limiters

Frequency selective limiters (FSLs), which selectively attenuate above threshold signals while allowing low power signals to pass with little attenuation, have potential application in maintaining the dynamic range of RF receivers in the presence of interference. Stripline FSLs, fabricated using thick yttrium iron garnet (YIG) films, are suitable for broadband, microwave applications but have typical threshold power levels of 0 dBm which is too high for many RF applications. Here magnetostatic wave (MSW) FSLs are described with frequency selectivity and threshold power levels at least 10 times lower than achieved with stripline devices. The performance of an MSW FSL operating in the UHF band will be presented and compared with a model for threshold power. Based on these results the performance limits of FSLs will be discussed with emphasis on reducing threshold power levels significantly below -40 dBm as required in potential GPS applications.