GB973347A - A non-reciprocal electromagnetic wave transmission device - Google Patents

Abstract

973,347. Non-reciprocal transmission devices. RAYTHEON CO. March 10, 1961 [March 21, 1960], No. 8865/61. Heading H1W. In order to obtain non-reciprocal attenuation or phase-shift, a polarized ferrite element is situated on the axis of a bend in a transmission line. The two-conductor transmission line 5, 6 of Fig. 2 is bent through 180 degrees and a disc 8 of ferrite arranged with its axis coincident with the axis of the bend. If the radius of the bend is #/2 (# is the R.F. wavelength), the magnetic R.F. field, denoted by arrows 10, will rotate about the centre of the ferrite disc at a rate 2#f radians/sec. Thus, by provision of an axial polarizing field H 0 of suitable strength, it is possible to create conditions for gyromagnetic resonance absorption or to modify the permeability of the disc, both these effects being non-reciprocal as regards R.F. energy propagated in two opposite directions. The same principle may be applied to strip lines and "sandwich" lines. The four-conductor line of Fig. 8 uses two conductive planes 25, 26 enclosing a pair of bent strip conductors 27, 28 separated by a dielectric sheet 29. Two polarized ferrite discs 30, 31 are situated within the bends between the strip and planar conductors. In the modification of Fig. 9, R.F. energy is propagated in the gap between protuberances 34, 35 on conductive plates 32, 33. A ferrite disc 36 is situated within a bend of the " gap " line. The surface-wave transmission line of Fig. 10 consists of a conductive core with a dielectric covering. Polarized ferrite discs 39, 40 are situated on either side of a bend in the line. In Fig. 11, the transmission line is in the form of a coaxial line of rectangular section. The line is bent through 180 degrees, the two limbs of the bend being separated by a partition 42. Two ferrite discs 22, 23 are situated within the bend on either side of the central conductor. A number of non-reciprocal attenuators or phase-shifters may be connected in tandem in the same transmission line and grouped together in a stack between the poles of a permanent magnet or an adjustable electromagnet. If the devices are resonant at different frequencies, a broad-band effect may be obtained.