Analysis and applications of quadrature hybrids as RF circulators

The operation of a quadrature hybrid as a power combiner is analyzed. The analytical results are compared with data measured experimentally using a 211 MHz cavity. Graphical solutions of the measured cases are in good agreement with analytical predictions. The use of the 90/spl deg/-hybrid as an RF circulator is also analyzed. The active operation of the harmonic cavity in the NSLS VUV-ring is used to demonstrate this application. This fourth-harmonic cavity is used to change the shape of the bucket potential to lengthen a stored bunch. Thus, a longer stored-beam lifetime can be achieved without compromising the high brightness of the VUV photon beam. If operated actively, the harmonic cavity would present a mismatched load to an RF generator. Thus, a need exists for a circulator. Similarities in operation between the 90/spl deg/-hybrid and a circulator are discussed.<
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