GB902446A - Improvements in or relating to radio and like radio transmitting arrangements - Google Patents

Abstract

902,446. Impedance networks. TELEFUN. KEN G.m.b.H. Oct. 25, 1960 [Oct. 28, 1959], No. 36592/60. Class 40 (8). [Also in Group XL (c)] A coupling arrangement connecting two radio-frequency transmitters S1, S2, to a load A, such as an aerial, comprises a four branch ring circuit each branch of which is a quarterwave #-section comprising a series inductance and two shunt capacitances. All the impedances are formed of short-circuited lengths of coaxial line, the inductive lines being inside the inner conductors of the capacitive lines. The two transmitters are connected to the ends of one branch having a surge impedance equal to that of the load A whilst the load A and a balancing load KA of equal value are connected to the ends of the opposite branch which has a similar surge impedance. The other branches have surge impedances approximately #2 times that of the branches so far described. In one construction of the coupling the four capacitors c connected to the four junctionpoints of the ring are formed of four lengths of coaxial line, parallel to each other and arranged in the form of a square, the lines are shortcircuited at their adjacent ends and also by adjustable sliders 5 (which may be ganged). The lines are between a quarter and a half wavelength long. Inside the tubular inner conductors of each capacitor is a further line short-circuited at the same end and also by an adjustable slider 6. These lines are less than a quarter wavelength long and form the inductances a and b. The sliders 6 may also be ganged. Connectors 1<SP>1</SP>, 2<SP>1</SP>, 3<SP>1</SP> and 4<SP>1</SP> connect the inner conductors of the inductive lines to the next adjacent connection points, which are the inner electrodes of the next capacitors. The arrangement may be modified (Fig. 5, not shown) so that two of the units are turned end for end and connections 1 and 4 appear at the opposite end of the assembly to connections 2 and 3. In a further embodiment (Figs. 6 and 7, the latter not shown), each inductor comprises two line lengths giving equal values of inductance, a/2 or b/2 as the case may be, these are situated one inside each inner electrode of the end capacitors of the #-section forming the branch and the interconnecting links thus lie symmetrically in the middle of each of the inductive elements. In this form there is one a/2 and one b/2 inductor inside each capacitor c.