Wideband Overmoded Liquid Calorimeter for High-Power Microwaves: Centimeters to Millimeters

The design of a liquid calorimeter with a closed absorbing load for measuring the energy of high-power microwave pulses in the range of 8–38 GHz is described. The calorimeter was designed to measure the energy of microwave pulses ranging from 1 to 500 J at a nominal power level of about 500 MW. The calorimeter includes a waveguide absorbing load and an automated control system. The waveguide absorbing load includes a segment of a circular overmoded cylindrical waveguide; the cylindrical wall is made of a dielectric pipe. The volume between the waveguide and the outer casing made of duralumin is filled with ethyl alcohol. Inside the waveguide, there is a cone made of duralumin, providing the best matching of the load. The automated control system includes a control and registration unit, an algorithm for determining the meniscus position, a power supply, a program that runs directly on the calorimeter control unit, and a control program for personal computer.