In-circuit, Non-Contacting, S-parameter measurement for planar circuits

A method for measuring S-parameters of a circuit embedded in a planar circuit environment is presented. The method utilizes an inductive and a capacitive probe. Experimental results are presented for probe measurements of reflection coefficient from 0.7 to 20 GHz with good agreement to verifying measurements up to 14 GHz. The method shows great promise for in-circuit S-parameter testing that has previously required physical modification or even complete disassembly to test sub-circuits in a microstrip environment.