GB1424267A - Radio frequency power divider - Google Patents

Abstract

1424267 Variable power dividers NATIONAL AERONAUTICS & SPACE ADMINISTRATION 14 June 1973 [15 June 1972] 28275/73 Heading H1W [Also in Division H4] A radio frequency power divider comprises an input port, two output ports, control means for varying the relative power available at the two output ports to effect a smooth and linear transition from full power at one output port to full power at the other output port, means for dividing energy applied to the input port into two channels, a pair of electrically controlled, variable phase shift means respectively disposed in the two channels for differentially varying the phase of the energies in the two channels, means for supplying differentially related control signals to the pair of phase shift means, whereby one control signal increases as the other decreases, and means for combining the phase shifted energies in the two channels and applying the output energy to the two output ports, the combining means being responsive to the relative phase of the energies in the two channels to proportion the output energy between said two output ports in dependence thereupon. In a first embodiment, a device 1, Fig. 1, splits the input into substantially equal parts, any imbalance being absorbed in a resistor 2. Equal powers are applied to phase shifters 3, 4, which may be voltage variable capacitor diodes. Bias voltages are applied from a source of differential control signals, and the phase shifters are designed to produce 45 degree phase shifts when said source supplies equal voltages. The voltages are varied from this value so that complementary phase changes are produced in the phase shifters. Thus, when either produces an overall phase shift of 90 degrees, the other produces zero phase shift (Figs. 2, 3, 4, not shown). The outputs from the phase shifters are applied to a 3dB hybrid coupler 5. With equal diode biases, equal powers appear at the output ports of the hybrid and, as the biases are varied, the power split is changed, until substantially all the power appears at one or other of the ports. In a second embodiment (Fig. 5, not shown) voltage variable capacitor diodes are shuntconnected by means of power dividers, to provide higher power operation. Stripline fabrication is employed, a device 17, Figs. 6, 6a, performing the functions of an equal-power divider 1, a resistor 2, and an output hybrid 5 (as in Fig. 1), and comprising coupling hybrids 6, 7. Two devices 18, one only of which is shown, are coupled to the device 17 by coaxial cables 33, 34. Each contains two equal-power dividers 8, which are terminated in voltage variable capacitor diodes 9, 10 with respective tuning stubs 11, 12. Bias is applied from a terminal 36 via a quarter-wave line 14, having by-pass capacitors 13, 15 at its ends.