Design and development of high power variable dual directional radio frequency coupler

Design and development of coaxial line-based 10–40 dB variable loop type dual-directional coupler for the frequency range of 50–500 MHz for 2 kW power handling capability has been presented in this study. The directional coupler has to be used in the radio frequency plasma experiment to detect the reflected power, so as to safeguard the system from unwanted reflected power. It consists of a main coaxial transmission line with two similar movable loop type coupling arrangements. The movable loops provide variable coupling for forward and reflected power separately, where the magnitude of coupling can be selected independently both for forward and reflected wave. The developed coupler has been tested where test results show return loss and isolation better than −10 dB and coupling from − 10 to − 40 dB in the frequency range of 50–500 MHz.