A novel standing-wave indicator in microstrip

Although there have been numerous applications for a standing-wave detector in microstrip for many years, there has until now been no clear idea as to how a reliable indicator could be built. This paper presents the practising engineer with a fixed probe/sliding load test instrument that has proved successful where travelling probe methods have failed. The circuit (or load) is printed on a very thin dielectric leaf so that it can be moved along the surface of the substrate proper (e.g. alumina), passing over a probe of special design etched into the ground plane. Details for extending the basic method to elements mounted in shunt with the microstrip are given.