Wideband tunable microwave devices using ferromagnetic film–gallium arsenide material structures

Yittrium iron garnet (YIG)–gadolinium gallium garnet (GGG) and iron (Fe)–gallium arsenide (GaAs) layer structures have been used, respectively, to construct wideband tunable microwave bandstop filters of the flip-chip type and the integrated type. For the former, a frequency tuning range of 2.5–23.0 GHz was accomplished at a magnetic field tuning range of 290–7300 Oe. For the latter, a comparable tuning bandwidth but of significantly higher carrier frequencies of 10.7–32.5 GHz has been achieved at a much lower magnetic field tuning range, namely, 0–4500 Oe. The advantages associated with the Fe-film-based bandstop filters should also accompany other analog microwave devices.