Study on Measurement of Scattering Parameters of Non-Coaxial Interface Devices

With the rapid advancements in communication technology, there has been an increasing emphasis on addressing EMC (Electromagnetic Compatibility) issues. When designing EMC at the PCB (Printed Circuit Board) level, having knowledge of the S-parameters (Scattering parameters) of non-coaxial interface devices is essential, which presents a significant challenge for accurate S-parameter measurements. To address this challenge, a T-shaped microstrip line is employed as the DUT (Device Under Test), and the full-wave model of the DUT, test fixture, and calibration standards is designed using HFSS (High Frequency Structure Simulator). Impedance discontinuities at the junction of the microstrip line and pad are compensated and optimized through the use of the anti-pad. The TRL (Thru-Reflect-Line) calibration method is employed to calibrate system errors introduced by the test fixture and obtain accurate S-parameters for the DUT. Both simulation and actual measurements demonstrate that this method accurately measures the S-parameters of the DUT within the frequency range of 0.1 GHz to 14 GHz. The method proposed in this paper offers a straightforward and efficient approach to accurately measure the S-parameters of non-coaxial interface devices, thereby facilitating accurate EMC design at the PCB level.