On the Matching and Tuning of a Helical Resonator: Mechanical and Electrical Solutions in X Band

The use of varactor diodes to match and tune an X-band helical resonator is compared to mechanical tuning. It is shown that only small corrections can be achieved with electrical solutions because of the V-1/2 variations of the junction capacity of the low-loss GaAs diode. For the time being, only mechanical devices allow large corrections for the matching and tuning of a helical resonator.