2-20 GHz non-uniform coupler for six-port reflectometer

In this paper a six-port reflectometer to be included in a near-field microwave microscope (NFMM) is presented. The reflectometer, made of five couplers based on non-uniform and offset parallel-coupled transmission lines, is proposed to achieve a broad frequency band [2-20 GHz], corresponding to the frequency range of the interferometer based NFMM. It becomes then possible to replace the vector network analyzer classically used in NFMMS.