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The micro-discharge effect limits the development of high-frequency microwave power components to miniaturization and integration. Therefore, it has become a focus of research to effectively suppress the micro-discharge effect, increase the micro-discharge threshold, and strengthen the environmental stability of high-frequency microwave devices. In this study, different elemental ratios of carbon (C)/silver (Ag)/titanium (Ti) composite films were obtained by multi-target magnetron co-sputtering technology and then systematically analyzed for micro-discharge effects. When the doping ratio of C/Ag/Ti was 3.538/1/0.013, the corresponding maximum secondary electron emission coefficient (δmax) decreased to 1.01 owing to the suppression of secondary electron emission by the increase in the content of sp2 hybrid bond. The micro-discharge threshold of Ku band waveguide filters coated with moderate C/Ag/Ti composite films showed an optimal performance of 10 000−12 500 W, which was increased by approximately 20 times. Moreover, the microstructure of the composite films exhibited higher density and flatness with a tiny increase in the titanium doping ratio, representing good environmental stability. Thus, the effective suppression of the secondary electron emission yield, significant improvement in the micro-discharge threshold, and enhancement of the environment stability of microwave components could be realized simultaneously by reasonably controlling the content of titanium in silver and titanium co-doped carbon-based composite films. [ABSTRACT FROM AUTHOR]

Voltage-tunable RF/microwave devices attract great attention due to their low power consumption; however, they still suffer from the fundamental dilemma between large tunability and low insertion loss. In this paper, yttrium iron garnet (YIG) polycrystalline thin films with low microwave loss (<3 × 10−4) were directly deposited on mica substrates via a van der Waals force and then transferred onto PMN-PT substrates. The in-plane magnetic anisotropy of YIG was tuned by the in-plane biaxial stress of PMN-PT, and an improved voltage tunability (175 MHz) of in-plane FMR fr was obtained due to the removal of the substrate clamping effect. Moreover, our samples still represent good frequency stability (4–12 GHz) during the tuning process. It is of significance for exploiting novel, portable, low-loss RF/microwave devices in the future. [ABSTRACT FROM AUTHOR]