GB1320294A - Broadcast antenna assembly - Google Patents

Abstract

1320294 Aerials AMPEXCORP 7 Feb 1972 [24 Feb 1971] 5520/72 Heading H4A An aerial assembly comprises an elongate conductive supporting structure 10, such as a vertically disposed tubular mast section, on which are mounted one or more bays 12 each consisting of two aerial elements 14a, 14b, having respective signal feeding means, and at least one director associated with at least one of said elements. Each director comprises a plurality of planar members 22, which are spaced along its axis, and are normal thereto. The directors are disposed so that they do not interest the radiation axis 16a or 16b of their associated element 14a or 14b and so that they cause overlapping of the radiation patterns of said elements. As described, two aerial arrays, on opposite sides of the mast section 10, are formed by a plurality of bays 12-1 to 12-5, which are mounted one above the other. The diameter of the mast section 10 is at least a quarter wavelength at the mean frequency of operation of the arrays. Each driven aerial element comprises a vertical slot, such as the slot 28 shown in the bay 12-2, behind which is a cavity 30, and which is fed by a respective array transmission line 48a or 48b. A dielectric cover 32 is placed over each slot. Mounted on each cavity 30 are two brackets 34, one on each side of the slot 28, from which extend director support rods 36, rearwardly and outwardly. Mounted on each rod 36 are planar members 22, which may be plates or discs, of solid or skeleton construction. Said members 22 have their respective major dimensions at least quarter wavelengths at the mean frequency of operation of the associated array. The two arrays, which may be staggered vertically by about a wavelength at their mean frequency of operation, have respective substantially omnidirectional radiation patterns 24, 26 and, since their is no significant coupling between the arrays, one may be used for the video transmission of a TV channel and the other for the sound transmission thereof. Another use would be for the arrays to transmit respective different complete TV channels.