GB766081A - Aircraft radio installation - Google Patents

Abstract

766,081. Aerials; aerial coupling arrangements. STANDARD TELEPHONES & CABLES, Ltd. Dec. 17, 1954, No. 36545/54. Class 40(7) The exterior surface of a metal-skinned aircraft is used as an aerial and is coupled to radio equipment within the craft by means of a substantially non-radiating linear conductor disposed externally to the craft but in close proximity to it. In one embodiment where the electrical length of craft is greater than half a wavelength at the lowest frequency to be used the aerial tuning unit 2 is located close to the roof surface of the craft. The "earthy" side of the output is connected directly to the metal skin of the craft at 3 and the other output lead is taken up a short feed-through mast 4, positioned close to the point 3, to one end of a conductor 5 which runs parallel to longitudinal axis of the craft. The length of conductor 5 is preferably equal to one eighth of a wavelength at the lowest operating frequency and the far end of it is supported by an insulator 6 mounted on the tail structure. The height c of the mast 4 is not critical and may be between 7 and 20 cms. for wavelengths of the order of 100 metres. The conductor 5 may be a copper wire 3 mm. in diameter coated. with polythene in order to reduce interference due to precipitation static. The radiation pattern of the aerial arrangement is stated to be substantially omnidirectional. In a modification for use when the electrical length of the craft approaches threequarters of a wavelength the conductor 5 is still made #/8 long but is coupled to the tuning unit at a point intermediate its ends. On end, in this embodiment, is electrically connected to the surface of the craft and the other insulated therefrom (Fig. 2. not shown).