GB793833A - Improvements relating to electromagnetic coupling arrangements - Google Patents

Abstract

793,833. Waveguide filter circuits. COMPAGNIE FRANCAISE THOMSON-HOUSTON. Jan. 20, 1956 [Jan. 21, 1955], No. 2023/56. Class 40 (8). [Also in Group XL (c)] An arrangement for coupling two radar sets or other radio-frequency sources operating at different frequencies to a common load consists of a length of line or waveguide 2-3 joining the two sources 10, 11; a further line or guide 4-5 connecting a matching load 13 to the intended load 12. At two points 6 and 7 the lines or guides are connected by 3 db directional couplers and mid-way between the couplers in each of them tuned filters 8 and 9 are arranged to pass energy of the frequency of source 10 and reject energy of the frequency of source 11. Preferably the filters are T. sections of waveguides with the cross-arm of the T in the connecting guides and the branch short-circuited so that their reactance is a minimum at frequency f and odd multiples thereof and a maximum at 2f and multiples thereof; f and the operating frequencies are so chosen that the source 10 is coupled to the output through both directional couplers and the source 11 through coupler 7 only. All the energy is fed to the load in each case and there is no interaction between the two sources. The common load may be a common aerial and it will be seen that where the sources are radar sets, return echo signals reach the appropriate radar. A plurality of coupling arrangements such as that shown in Fig. 1, may be used to link any number of radar sets to a common load, the sets being coupled in pairs and then the pairs being coupled and so on as necessary. Where the number of sets is not exactly 2n (n being any integer) one or more coupling units may be omitted. The coupling of 4 and 8 sets is described (Figs. 3 and 5 respectively, both not shown) and the arrangement of the radar frequencies and filter resonances discussed.