Patent GB-849281-A (GB)
Title: Improvements in arrangements for supporting members in collapsible angular relationship to one another
Inventor: MORGAN JOHN TREVOR
IPC: H01Q19/04
Filed: 1957-05-10
Abstract: 849,281. Aerials. BELLING & LEE Ltd. May 23, 1958 [May 10, 1957], No. 14880/57. Class 40(7). [Also in Group XXV] The parasitic metal elements 10, 11 and 12, 13 of an indoor television aerial, Fig. 1, are mounted on a cross arm 1 by means of locking plates 2 which allow the elements to be rotated into operative and inoperative positions normal, and parallel, to the cross arm 1 respectively. As shown each plate 2 is secured transversely to the cross arm by a rivet 8 and by lugs 6, 7 on the sides of the plate which engage corresponding apertures in the cross arm 1. Each element (10-13) is rotatably secured, at one end to an associated plate 2 by a rivet 14. If desired the two rivets 14 on a plate 2 can be linked together by a metal bracing strip, not shown. During the final rotational movement of an element into its operative position it rides over the corresponding inclined surface 9a of a turned-up corner of the plate and then snaps into a space A between the turned-up comers at that end of the plate. When moving an element back into its inoperative position it is first pulled out of its normal plane of rotation, to avoid the corresponding surface 9a, and then folded down into alignment with the cross bar 1. The continuous limb 16 of a folded dipole 15 is pivoted at 43 to the cross arm 1 the [lower and adjacent ends upper parts] of the broken limbs 17, 18 being connected to the arm 1 by a resilient insulator made e.g. of polythene. The insulator, Fig. 8, is recessed to receive the free ends of the limbs 17, 18 each of which is secured by a bolt 22, or 23 which passes through aligned holes in the insulator and the corresponding end of the limb 17, or 18 and carries a wing nut 24 or 25. The transmission line for the aerial is connected to the dipole by the nuts 24, 25 and the bolts 22, 23. The outer face of the insulator carries two ridges 34, 35 for snap engagement over, when a tapering spigot 38 engages an aperture 39 in the cross arm. A rivet 43 Fig. 2 secures the dipole limb 16 to an insulating bush 42 located in an aperture 40 in the cross arm 1, insulating washers 45 being interposed between the limb 16 and the cross arm. Before the dipole can be rotated about the pivot 43, into an inoperative position, the insulator 19 must be first pulled out of engagement with the cross arm 1. In a large aerial array the pairs of parasitic elements which, when folded, would not project beyond the ends of the cross arm 1 may be of one length. The cross arm is secured at 45 to a mast 46; alternatively, or in addition, it may have means 47 for securing it to the ball-andsocket joint of a wall mounting. The parasitic elements 48, 49 of an outdoor aerial, Figs. 11,12, are secured to a cross arm 50 by a channel section saddle 55 which has grooves 51 in its side walls 53 to receive the cross arm 50 and carries a locking plate 56. The latter has inclined end portions 59, 60 which are shaped as shown for making snap engagement with the parasitic elements 48, 49. Each parasitic element is secured to the saddle 55 by means of a U-shaped clamping plate, 73 or 74, which is pivoted by a bolt to the saddle 55. The latter is secured to the cross arm 50 by a screw 79 and wing nut 80. Further minor modifications of the arrangements are described. Specifications 807,941, 829,412 and 846,969 are referred to.