The applications of smart materials and structures have grown substantially in aerospace industries. With smart structures and materials, performance has the potential to improve and extend the capability of a device. As a first experience in this field, EMS has investigated the integration of multilayer piezoelectric actuators into an RF bandpass filter to compensate for the frequency shift induced by thermal distortion of the resonator tuning posts. The purpose of a bandpass filter is to separate frequencies in a communications signal. This type of filter lets a certain range of frequencies pass through, from the input port to the output port, while frequencies below and above the limits are rejected. A bandpass filter must keep its stability in temperature. A variation in temperature induces a frequency shift of the passband. In this project, EMS Technologies and Sensor Technology teamed for a collaborative work. Piezoelectric actuators have been developed and manufactured by Sensor in order to achieve the requirements specified by EMS. A breadboard was adapted to embed the piezoelectrics. A test setup was prepared and the breadboard was tuned and tested over a wide range of temperature. Although the previous design was relatively stable, there was still room for improvement. Over a temperature range of 50 deg C (-10 to 40 deg C), the frequency shift was 0.0097 % (or 0.150 MHz). However, with the controlled piezoelectric actuators, the frequency shift is three times smaller, down to 0.0033 % (or 0.050 MHz). A trade-off in terms of electrical performance in temperature, mass, integration complexity, risk, cost, etc. shows that in future applications, active control of bandpass filter with piezoelectrics should be considered. Additional work is required for flight qualification of the piezoelectrics and to reduce the weiight and cost of the driving electronics.
Active stabilization of bandpass filter with multilayer piezoelectric actuators
Aktive Stabilisierung von Bandfiltern mit piezoelektrischen Mehrschichtaktoren
2002
12 Seiten, 8 Bilder, 2 Tabellen, 5 Quellen
Aufsatz (Konferenz)
Englisch
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