RF ratiometer facilitates continuous VSWR monitoring of medium range tracking radar

The RF ratiometer is described which is used for continuous monitoring of the voltage standing-wave ratio (VSWR) in the medium range tracking radar being developed at the Thumba Equatorial Rocket Launching Station in India. In this RF ratiometer, the power standing-wave ratio is measured and its square root is taken to indicate the VSWR. The system design is outlined, the full-wave rectifier is described, and schematic diagrams are presented for the logarithmic, FET, and ratio circuits. The response characteristics of the ratiometer are plotted as the log of the input voltage amplitude vs the log of the output voltage amplitude.