GB1248990A - Isolator - Google Patents

Abstract

1,248,990. Isotators and circulators. NIPPON HOSO KYOKAI. 25 Sept., 1969 [2 Oct., 1968], No. 47209/69. Heading H1W. [Also in Division H4] A wide-band isolator comprises a three-port circulator has one port terminated by a resistance, the outer conductor of the circulator being connected to earth by a tuned circuit. As shown in the exploded view of Fig. 3, the circulator comprises a U-shaped ground conductor 22, polepieces 20, 20<SP>1</SP>, outer conductors 13, 13<SP>1</SP>, ferrite elements 15, 15<SP>1</SP> and an insulative disc 14 bearing a printed pattern of intermeshed conductors. The outer conductors are insulated from the ground conductor and a circuit 24 tuned to the centre frequency of the operating band of the circulator is connected between them. One port 18 of the circulator is connected through an absorbing resistance 26 either to ground (as shown) or to one of the outer conductors. A circuit 25, tuned to accept frequencies within the pass-band and reject those outside it, may be connected in series with the resistance. The ground conductor 22 serves as a common terminal for the three ports. The equivalent circuit is shown in Fig. 6. A balanced version of the isolator using two circulators is shown diagrammatically in Fig. 7b. In this version, no connection is made to ground, the tuned circuit 24 being connected between the outer conductors 31, 32 of the two circulators and the resistance 26 between two corresponding ports 33, 34. The two circulators may be mounted one on top of the other between common polepieces (Fig. 7a, not shown). The intermeshed pattern of the inner conductor is shown in Fig. 10a where primed references and dashed lines indicate conductive patterns printed on the reverse side of the insulating disc 46. Connections are made through the disc at points 50, 50<SP>1</SP> &c. and one end of each of the three intersecting conductor-pairs is connected to a terminal 19 (Fig. 3) on the outer conductor. A further version of the intermeshing pattern (Fig. 11, not shown) is described. In this, the conductor pairs are connected at one end to a common terminal in the form of a peripheral conductor printed on one side of the disc.