S-Band traveling-wave parametric amplifier using a filter circuit

An operating S-band traveling-wave parametric amplifier is described. The amplifier signal-idler circuit consists of four rectangular cavities centrally loaded by variable capacitance diodes. The cavities are inductively coupled through irises which may be exchanged to vary the size and characteristics of the passband. The pump, at C-band, is supported by a second circuit capacitively coupled to each of the signal cavities. Stable gains of greater than 20 db have been obtained by incorporating non-reciprocal loss ferrite elements in the irises between cavities. Gains of 10 db have been achieved over 10% bandwidth and more gain over wider passbands can be obtained by simply adding more cavity sections. The critical effect of pump phase shift on stability, shape of response curves and bandwidth is illustrated. Results of noise measurements will be given and compared with theory.