GB624776A - Improvements relating to electro-magnetic waveguides - Google Patents

Abstract

624,776. Wave-guides. MILLING, M. C. CROWLEY-, and METROPOLITANVICKERS ELECTRICAL CO., Ltd. Oct. 30, 1946, No. 32233. [Class 40 (v)] A telescopic joint between two sections of wave-guide, slidable one over the other, is provided with matching means to prevent reflection at the joint, and sealing means to prevent leakage. One of the sections may be a connection between two main wave-guides of equal cross-section. Matching may be effected by stepping the wave-guide wall to form a transformer section, or by a suitably placed diaphragm or post. If the impedances of the guides are unequal, but bear a definite relationship, they may be matched by removing a length #g/4 of two adjacent faces of the smaller guide 2, Fig. 6, where #g is the geometric mean of the wavelengths in the two guides. Leakage at the joint may be prevented by providing quarter-wave chokes in one or both of the sliding surfaces. The chokes may be formed by a quarter-wave recess in the outer surface of the inner guide, or by two recesses spaced apart by a quarter wavelength. As shown, Fig. 9, a quarter-wave recess 9 is formed in the outer surface of the inner guide 2, while a second quarter-wave recess 11 is formed in the inner surface of the outer guide 1. In another embodiment, Fig. 10, the outer wave-guide 1 slides between the double walls of the inner wave-guide 2. Quarter-wave recesses 9, 14 are formed in the opposing faces of the double wall. Specifications 624,780 and 624,781 are referred to.