A broadband 3–29 GHz reflectometer with a frequency compensated multilayer sixport structure

In this paper, a planar broadband sixport reflectometer structure is presented. A frequency range from 3 to 29 GHz could be achieved by merging broadband components into a single multilayer PCB stackup with an area of 66×55 mm2. The reflectometer architecture used herein allows a frequency independent q-point configuration of the sixport by implementing microstrip linelength compensation. Broadband matching of around -10 dB has been achieved at all ports in a frequency range from 1 to 30GHz. Furthermore, sufficient coupling from DUT port to measurement output could be reached in a range from 2 to 29 GHz. Frequency compensation of the structure and an optimal q-point constellation of 120-120-120 have been verified by measurement. Due to its broadband functionality, compactness and cost efficiency, the proposed system is suitable for a wide range of microwave measurement applications.