GB908028A - Improvements in antenna erecting apparatus - Google Patents

Abstract

908,028. Aerials. AINE, H. E., and SEINWOHL, A. April 9, 1959 [April 10, 1958], No. 12063/59. Class 40 (7). [Also in Group XXI] An antenna mounting, particularly suitable for combination with a buoyant life preserver, exposure suit or life raft consists of a hollow inflatable envelope carrying the antenna and means for inflating the envelope so as to erect the antenna ready for use. A device according to the invention useful with recoverable drone aircraft or missiles is also described. In an embodiment in which the mounting is incorporated into a life preserver 3 the aerial itself consists of a thin flexible metal braid or a conducting foil and is secured to the inside of the mounting 1 by rubber cement or dielectric adhesive tape. The support 1 is substantially conical and may be made of rubberized nylon fabric, or polyethylene, sealed in a gas-tight manner to the outer envelope of the life preserver. It communicates with the uppermost of three separate chambers inside the life preserver and is inflated and erected automatically when that chamber is inflated by a suitable cartridge placed in one of the housings 27. The size of the cartridge should take into account the added volume to be filled in the support 1. In a modification, a plurality of inflatable envelopes are provided to erect the aerial and they are nested one within the other with each communicating with different ones of the life preserver chambers. In this way the antenna is erected when at least one chamber is inflated. The aerial element 8 is coupled by a transmission line 9 extending inside the top chamber of the life preserver and along the tube 19 sealed thereto to a gas and water-tight connector on a transmitter box carried in an external pocket on the life preserver. The transmission line 9 may conveniently be coaxial and have its inner conductor connected to the element 8 and its outer conductor segmented and attached to a ground plane held in position against the inside surface of the life preserver below the aerial. A suitable ground plane assembly consists of a thin pliable apertured disc of copper with a plurality of thin flexible conductors extending radially therefrom. The support 1 is stored prior to use by being folded up and retained at the rear of the life preserver beneath two elastic bands 17, 18. Inflation causes it to be erected through the slot between the bands as indicated by the chain-dotted lines in Fig. 3. If preferred, the aerial and transmitter assembly may be separable from the life preserver and attached thereto by snap-fasteners (Figs. 8, 9, 12, 13 and 14; all not shown). In this embodiment a separate gas cartridge on the assembly is capable of inflating the aerial support and also a shallow chamber extending round the base of the support and carrying the ground plane. An arrangement of similar type may be attached to the back of an exposure suit to enable the wearer thereof to transmit radio signals (Figs. 15 and 16, both not shown). Fig. 17 indicates how an antenna-carrying support 77 may be erected in conjunction with the inflatable tubular wall of a life raft. A similar ground plane 79 to that described is used and the aerial retained by elastic bands 84, 85 when not in use. If preferred the support 77 may be sealed off from the raft wall and have its own inflating mechanism. It could also be disposed on top of a canopy arranged over the raft. An embodiment for drones or missiles is shown packed in Fig. 11 and erected in Fig. 10. An electrically fired gas cartridge 58 is provided to generate the gas necessary for filling the inflatable aerial support 50. Firing the cartridge causes the support to force the cap 61 off the container 51 and to extend upwardly, as shown in Fig. 10. The coaxial lead 52 extends to within a quarter of the working wavelength of the top of the support. From this point the inner conductor 53 continues upwards to the top of the support and the outer conductor is spread out and attached to the upper ends of a plurality of downwardly-extending thin conductors 55 mounted on the inner surface of the support. These conductors may be replaced by a lining of flexible foil if preferred.