CAO liangzu ,WANG shuai, LIN cheng

(School of Mechanical and Electronic Engineering, Jingdezhen Ceramics Institute, Jingdezhen 333001)

Abstract: Electrically tunable microwave bandpass filters have been used widely in microwave multichannel receivers and electric antagonism systems. Development of electrically tunable filters had been described. To counter design, structures and properties, tuning theory, tuning elements, microwave reality, passband characteristic had been summarized. The future prospects had been explored.

Keywords: microwave filter, electrically tunable, varactor, piezoelectric transducer, ferroelectric thin film