Permittivity sensor based on 60 GHz patch antenna

In this paper, a sensor based on a 60 GHz rectangular patch antenna is presented, for characterising materials based on the permittivity variation in the reactive near-field. The resonant frequency of the patch antenna is a function of the dielectric ambient around it. Thus, the resonant frequency is scaled accordingly, based on the permittivities of various materials under test. Therefore, the permittivity information is translated to a resonant frequency shift of the patch antenna. The patch antenna was fabricated on Isola Astra 300 microwave substrate and measured with different solid and liquid material on top of the patch antenna. In addition to that a simple readout circuit was proposed and realized in 0.25 μm SiGe:C BiCMOS, which can be used in the future to convert the reflected power of the antenna into a corresponding DC-value.