GB649067A - Improvements in and relating to waveguide devices - Google Patents

Abstract

649,067. Wave meters. MINISTER OF SUPPLY. Oct. 15, 1948, No. 26883. [Class 37] [Also in Group XL (b)] A detecting device is connected to one T-arm of a hybrid T-junction fed with ultra shortwave energy through the other T arm, one of the in-line arms is closed by an adjustable short-circuiting piston and the other in-line arm is coupled to or continued as a wave-guide or other transmission path, long compared with the operating wavelength and having an unmatched termination. The arrangement may be used as a wave-meter by feeding the wave to be measured into the shunt T-arm 4 and adjusting the position of the short-circuiting piston 5 in the in-line arm 1 so that an indicator connected to the detector coupled to the series T-arm 3 shows zero power in this arm. In-line arm 2 is connected to a waveguide 6 of the order of a hundred wave lengths long with an unmatched termination. Energy fed in shunt arm 4 enters arms 1, 2 in phase and, by adjusting piston 5, the reflected energy may be made to arrive at the junction in phase, giving zero power in series arm 3. The long path in guide 6 increases the adjustment of piston 5 necessary to give a zero reading, and the piston adjusting means may be calibrated in frequency. The long guide 6 may be coiled or folded or may be replaced by a coaxial line or free space path.