Application of circular waveguide couplers in high power microwave measurement

The paper introduces the design, calibration, test and application of the circular directional couplers. Taking X-band directional coupler as an example, the structure parameters are numerically optimized based on the small-aperture coupling theory. Its coupling coefficient can be stabilized within (552) dB and the corresponding isolating coefficient is greater than 80 dB. According to the numerical result, the X-band directional coupler is machined and tested. The result agrees well with that of simulation. Further high power microwave (HPM) experiment demonstrates that the coupler is of high power handle capacity and can satisfy the experimental requirements. Such directional couplers have been widely used in our online measurement of the HPM devices.