GB1105354A - Improvements in radio antennas - Google Patents

Abstract

1,105,354. Aerials. NORTHROP CORPORATION. 2 March, 1966, No. 9215/66. Heading H4A. An aerial comprises a conductive, nearly closed, ring 36 from the extremities of which a pair of conductive legs 37, 38 extend at rightangles to its plane to a common connector, such as a ground plane 40. A matching stub 42, extending radially inwards from one extremity of the ring, is connected to the inner conductor 45 of a coaxial cable 46, the outer conductor 49 of which is connected to the ground plane 40, and a radio set 50 is connected, to the aerial through the said cable. Insulating support posts 41 may be provided for the ring 36 and a tuning or loading capacitor 43 may be connected to it at the point on its perimeter farthest from the legs 37, 38. It is stated that the combined lengths of the legs and the ring should preferably be from 0À25# to 0À5# (#= optimum wavelength), that the aerial gives vertically polarized radiation, and that it is usuable over a two-to-one frequency range. The ground plate 40 may be constituted by the top of an automobile or other vehicle. In a second embodiment, instead of the matching stub 42, there is provided a coupling collar (51), Fig. 2, located on the ring (36a) at a short distance (j) from one extremity, and the inner conductor of the coaxial cable (46a) is connected thereto. It is stated that with a cable of 50 ohms impedance, (j) is about 0À0007#. In a third embodiment, two concentric coplanar loops (36b), (36c), Fig. 3, are provided, each operating over a different frequency range. Either separate coaxial cables, or a single twocored cable (46b) may be used for feeding the loops, in association with an aerial selection switch at the radio set 50.