GB870873A - Improvements relating to couplings between waveguides - Google Patents

Abstract

870,873. Radar; aerials. COMPAGNIE FRANCAISE THOMSON-HOUSTON. Dec. 12, 1958 [Dec. 12, 1957], No. 40191/58. Class 40(7) [Also in Group XL(b) ] A radar or antenna-coupling system includes a junction 11 (see Group XL(b) ) coupling a circular waveguide 1 to a pair of rectangular waveguides, 2, 3 whose axes are arranged at right angles. The distribution of energy between the guides 2, 3 depends upon the polarization of the wave propagated in the circular guide 1. Thus, if the guide 1 is connected via a rotatable section 23 to a coaxial-line feeder 21, the orientation of section 23 determines the distribution of energy between two antannae connected respectively to guides 2, 3. The radar system of Fig. 4 comprises two junctions 11, 24, the circular branches of the junctions being aligned and coupled together through a ferrite rotator 27. When the rotation is zero guide 3 is coupled to guide 26 and guide 2 to guide 25. A rotation of 90 degrees commutates these couplings. Thus, if guide 26 is connected to a dissipative termination, signals from guides 2 and 3 may be applied in rapid alternation to guide 25 which may feed the I.F. section of a radar receiver. The two signals may respectively be echo pulses and reference pulses, the latter being used to regulate the gain of the receiver. Alternatively, sum and difference echo signals may be fed alternately to the same amplifier. In the radar system of Fig. 5, energy from transmitter 35 is divided at junction 34 into equal parts and fed to junction 11 through guides 2, 3. The polarization of the wave in the circular output guide 29 is determined by an adjustable 0 to 360 degree phase-changer 40 in the guide 3. Received energy is distributed between receivers 36, 37, the amplitude distribution being used to determine the polarization of the signal. In a modification (Fig. 6, not shown), the whole input energy is applied to the guide 2 and the polarization of the transmitted signal is regulated by a phase-shifter in the circular waveguide 29.