Fully Printed VO2 Switch Based Flexible and Reconfigurable Filter

Frequency reconfigurable filters are high in demand because they can cover multiple frequency bands, thus minimizing system level cost and size requirements. Another emerging trend is the flexibility or conformability of the electronic components, so that they are suitable for mounting on non-planar objects as well as for wearable applications. In this work, we demonstrate a frequency reconfigurable bandpass filter that has been fully printed on a flexible Kapton substrate. The frequency reconfigurability has been achieved through a switch made of Metal Insulator Transition (MIT) material Vanadium-di-oxide (VO
2
). The VO
2
switch has been printed through a custom ink. The switch is in OFF condition (insulating condition) at room temperature and turns ON (becomes conductive) at MIT temperature of 68°C. The microstrip bandpass filter employs dual mode resonators and can switch from 4.0 GHz to 3.7 GHz. The required thermal bias is provided through a printed heater which is attached to the backside of the filter. Due to the flexible Kapton substrate and the printing process, the prototype of the filter is highly flexible and low cost. Measured results are promising and in good agreement with the simulation results.