A thick-film coplanar probe for time domain measurements

The design, fabrication, and characterization of coplanar probes are presented. The probes are designed to work as launchers/adapters for performing wideband microwave measurements on planar geometry lines. The probes are made in the form of tapered coplanar lines, fabricated on alumina, teflon, and teflon-ceramic composite substrates. The time-domain reflectometry (TDR) technique was used to characterize the probes. Equivalent networks for the probes are developed using the modified transient circuit analysis program (MTCAP) by fitting a simulated TDR response to the measured TDR waveform and using a circuit simulation program (e.g. SPICE) to analyze the obtained equivalent network. The equivalent network of the probe thus obtained can then be used to de-embed the probe´s contribution to a wideband microwave measurement, and thereby reducing measurement errors