| 摘要 |
709,676. High-frequency coupling devices. PHILIPS ELECTRICAL INDUSTRIES, Ltd. May 6, 1952 [May 9, 1951], No. 11436/52. Class 40 (8) A high-frequency coupling device comprises two mutually perpendicular input loops 3, 4 situated within a cylindrical waveguide 5 and an output loop 1 rotatable about the axis of the guide. A rotating magnetic field is produced by the loops 3, 4 whose fields are of equal amplitude but 90 degrees out of phase with respect to each other. It can be shown that the voltage induced in the output loop 1, when this loop is at an angle α to a horizontal line perpendicular to the axis of the rotational field, is equal to V sin (#t+α), i.e. the output voltage has a phase angle equal to α and an amplitude independent of α. This is only true when the magnetic fields are homogeneous, a condition not realizable in practice. If, however, the loop 1 is coupled to the rotational field by the cylindrical waveguide 5 whose diameter d is smaller than .578 times the wavelength # corresponding to the frequency of the rotational field, the inhomogeneit'es in the field are damped out and a pure circularlypolarized H 11 mode field is produced near the loop 1. The best suppression of undesired waveforms occur when d <#/10. |
