Complex permittivity determination based on a radio frequency device

•We propose a new on-wafer four port device for measurement complex permittivity of materials over the frequency range from 1.5 GHz to 2.75 GHz. Four port tests improve the accuracy and avoid multiple solution problems.•Complex permittivity of materials can be calculated by two measurements, one measurement is for the empty device and the other for the material under test loaded one U-shape slot-line of the device.•We analysis the measurement results of Teflon and AR1000 with different length (5 mm and 10 mm). That is, the longer the length of the MUT, the higher the accuracy of the calculated results. Also, the application of the current method is discussed.