New microwave circuits for communication and sensing systems

Posted on Friday 16th May 2014

Four-channel-filterProfessor Michael Lancaster, Xiaobang Zhang, Wenlin Zia and Yi Wang were awarded College Best Publication November 2013 for the paper Novel Multiplexer Topologies Based on All-Resonator Structures"

We all now use complex microwave systems in our everyday lives including broadcast, television mobile phone communications, internet infrastructure, weather prediction and many more. Such systems have developed over many decades and their performance depends upon the individual components upon which they are built. One essential component is the filter; this circuit lets through the required signal and cuts out any interference which will disrupt the operation of the system. Because of their importance, microwave filters have been studied for many decades and there are many examples of different design techniques as well as many different realisations.

Work in the School of Electronic, Electrical and Computer Engineering has been on new types of very high performance filters and over a number of years these have been based on novel materials such as superconductors or ferroelectric and/or new fabrication technologies such as micromachined circuits. The expertise gained has not only allowed the research group to utilise new materials and technologies but also to develop new design techniques for filters and circuits with multiple filtering capabilities.

The research group has been instrumental in developing a new coupled resonator approach to complex interconnection between resonant structures. Normally filters have one input and one output, but the techniques developed allow for multiple inputs and multiple outputs. Although these are made conventionally, the new design technique allows higher performance in a smaller size. The group has discussed the technique in a number of invited workshops and published extensively. The latest publication shows a unique four output version with a detailed description of the methodology . The work is supported by EPSRC which provided £1.5M support over 6 years for this and work on terahertz micromachined devices. Recently support has come from a joint project with European Space Agency and Airbus Defence and Space whose interest lies in the lightweight, high performance solution suitable for integration in satellite systems. The specific component under investigation is a new type of power amplifier using the resonator based structures to combine multiple amplifier channels together with integrated filters. The structures are currently being built at the European Space Agency and are expected to remove the need for additional external filtering altogether reducing the satellite payload considerably.

By Professor Michael Lancaster

Image caption: A four channel filter operating at 10 GHz