Design of an E-H tuner and an adjustable directional coupler for high-power waveguide systems

The calculation and experimental results for a magic tee with movable choke plungers in - and -arms for the tuning the coupling-factor and RF phase of high-power accelerating cavities are presented. The investigations were carried out at 2.797 GHz and 1.3 GHz. The socalled E-H tuner shall provide the possibility of independent adjustment of external Q-factor and RF phase for the TESLA cavity structures. The Q EXT of the cavity structures must be tuneable in the range from 0.9*10 6 to 9*10 6 to match the RF system under different beam conditions. For matching the waveguide power distribution system to cavities with different quench thresholds, adjustable directional couplers are necessary. A hybrid coupler with a coupling factor of 3.0 dB and an adjustable range of ±1 dB at more than 25 dB directivity was calculated. The adjustment elements of this coupler are variable choke plungers in two additional H-arms opposite the coupling-slot.