GB582856A - Improvements in or relating to electromagnetic radiators or receivers - Google Patents

Abstract

582,856. Wave guides. BIRKS, J. B. July 5, 1944, No. 12864. [Class 40 (v)] An ultra-short-wave radiator or receiver comprises a section of wave guide of such dimensions that at the operating frequency only H01 and H10 waves can be propagated, the two modes having different phase velocities such that their mutual phase relationship becomes changed by 90 degrees in passing along the guide section. Fig. 1 shows a longitudinal, and Fig. 2 a transverse section of the guide. Energy is conveyed to the circular guide 10 by a radial probe 13. The guide 10 is closed at one end 12 and at the other opens into a guide 15 of rectangular section with the opposite end 16 open. The dimensions a, b of the rectangle and the length of the guide 15 are such that the wave H01 is advanced in phase by 90 degrees relative to the other wave H10 in passing along the guide 15, the two waves being thus in quadrature at the exit plane 16. This gives rise to a rotation of the direction of polarization of the emitted wave, the polarization being circular if the probe 13 is set at 45 degrees to the sides of the rectangular guide, and elliptical if other angular relations are adopted. The device may be employed in reception as well as transmission.