A method to enhance the accuracy of RF power measurements in particle
accelerator high-frequency systems
Abstract
This letter proposes a method for accurately calculating RF power at a
standing wave (SW) transmission line system. It uses two directional
couplers and a low-level radio frequency(LLRF) control system. The RF
power is calculated from the proposed equations using amplitude and
phase measurements of the coupling signals from the two directional
couplers. The method is demonstrated adopting two directional couplers
with directivity 26 dB and 28 dB respectively at 162.5 MHz over a whole
wavelength range. The average power errors observed when using a single
directional coupler are about 6.6% and 5.8% respectively, and the
calculated power error can be reduced to about 1.0% through the
proposed method.