GB592120A - Devices for the transmission or reception of ultra-high frequency electromagnetic waves - Google Patents

Abstract

592,120. Wave-guides. WESTERN ELECTRIC CO., Inc. Dec. 31, 1943, No. 21942. Convention date, Nov. 28, 1941. [Class 40 (v)] Wave-guides are arranged to emit or receive waves by providing them with a succession of transverse slots, or with a continuous longitudinal slot. The guide may be of rectangular section, and its E-dimension may be reduced gradually or in steps towards the end of the guide. Several such aerials may be combined as an array. Fig. 4 shows a radiating termination of a rectangular guide for H11 waves, the E-dimension being gradually reduced, and the slots 3 being across the H-dimension. If there are. several slots per wavelength, the main direction of radiation makes an angle with the guide axis, the cosine of which is equal to the ratio of the velocity of light to the phase velocity in the radiating portion of the guide. The slots may be wider towards the closed end of the guide, and the sum of their widths may advantageously be made equal to the E- dimension of the feed guide. When the guide is of stepped form, the slots may comprise the portions at right, angles to the axis and each slot may be provided with an outwardly flaring metal extension (Figs. 2 and 3, not shown). The slots may run obliquely across the H- dimension (Fig. 5, not shown). When a longitudinal slot is used, Fig. 6, it may be of even width or may widen towards the outer end (Fig. 7, not shown). Two radiating guides may branch from a single feed guide and the obtuse angle between them may be such that both give maximum radiation in the same direction (Fig. 9, not shown). If the slots are spaced a wavelength apart, broadside radiation results, and secondary lobes may be avoided by fitting rectangular horns 6 to each slit 3, Fig. 10, the open ends of which are contiguous. The guides may be filled with material, such as polystyrene, having a high dielectric constant. In Figs. 11 and 12, the feed guide 1 is connected to the radiator 16 through a diverging guide 17, and the slots across the face of the radiator are formed by the gaps between a number of triangular prisms 11, the sides of which form flared outlets from the slots, whilst their rear faces lie successively closer to the back plate 14 of the tapered distribution passage 15. If the slot spacing is equal to the wavelength in the passage 15, the radiation is broadside. The diverging guide 17 may be folded on itself to save space, or may be replaced by the coupling device shown in Fig. 15, in which the feed guide 1 is terminated in branch guides 24, 25 slitted at 26 to emit wave energy into a subdivided guide 27. This may be open at its forward end to emit radiation, or to feed the passage 15, Fig. 12. In an alternative coupling device (Fig. 18, not shown), the feed guide 1 has a longitudinal slot in one face, the slot being divided into portions separated by short triangular prisms which form flaring passages leading into a wide rectangular guide feeding the passage 15 of Fig. 12. Two co-planar radiators such as shown in Fig. 11 may be mounted for universal movement, one or both being arranged for reception, or three units, Fig. 24, may be used in an object-locating system, the outer units 10 as receivers and the central unit as transmitter. The outer units may be arranged to operate with overlapping beams, and by frequency wobbling or other phasing adjustment the two beams may be made to diverge variably. In Fig. 22, the distribution passage 14 behind the slotted radiator is filled with solid dielectric 36 which is extended through the slots as wedge-like projections 43. A pair of main tapering guides 41, Fig. 25, disposed at an angle to each other are provided with spaced slots each of which opens into a pair of diverging guides 42 with longitudinal slots. Guides 42 are reduced in length towards the outer ends of guides 41, the slots of which may also vary in width. A concentrated beam in the direction of the axis of the main guide 1 is produced. In Fig. 27 the radiator panel is of triangular form, a feed guide being branched to two wedge-shaped guides 45 with longitudinal slots 46 communicating with a triangular chamber bounded by a metal base-plate on one side, and by a series of spaced triangular prisms 48 on the other. Four such panels may be arranged to form a square (Figs. 28 and 29, not shown), two of them giving horizontally-polarized waves being used for transmission, and the other two being used for the reception of verticallypolarized waves. Specifications 515,684 and 592,162 are referred to.