A novel open-resonator system for precise measurement of permittivity and loss-tangent

A simplified open resonator system is developed for the first time for the measurement of permittivity and loss tangent of low-loss materials with high accuracy. In this new system, a cavity length variation technique and a quasioptical detection technique are developed and implemented. The cavity length variation technique makes it possible to use only fixed frequency sources. The use of the quasioptical detection technique employing a lens refocusing system and an ultra sensitive liquid helium cooled detector allows us to utilize only one fixed frequency source in the system, This novel open-resonator system has a much simpler structure, it is inexpensive and provides same level of measurement accuracy compared to the system using a super-heterodyne receiver (two fixed frequency sources). Permittivity and loss tangent data of a number of fused silica specimens are measured using this simplified open resonator system and are compared to data obtained by the open-resonator system using a super-heterodyne receiver.