GB628584A - Antenna system - Google Patents

Abstract

628,584. Aerials. STANDARD TELEPHONES & CABLES, Ltd. Oct. 4, 1946, No. 29656. Convention date, June 19, 1945. [Class 40 (vii)] In a slot aerial comprising a conducting member formed with an aperture across opposed edge portions of which energy transfer (i.e. feeder) means are coupled for establishing a plurality of spaced current maxima, means are provided for creating impedance to the occurrence of current maxima in certain areas of said member. In the arrangement of Fig. 1, in which a circular aperture 2 is provided in a conducting sheet 1, the impedance means comprise small slits 10, 11 ... 13, cutting the path between the feed terminals 2a, 2b of those points at which the undesired current maxima would otherwise be established. In an arrangement in which three elongated slots are formed in a conducting sheet (Fig. 2, not shown) the operative extent of the sheet associated with each slot is determined by suitably positioned slits (as in Fig. 1), and additional slits crossing the latter slits are provided to set up effective impedances between the three radiating areas. An arrangement producing a radiating area having two current maxima 20a, 20b, has the desired area defined by a circular skirt 23, Figs. 3 and 4. In a modification of the latter arrangement the skirt instead of being circular is comprised of two sections extendirig parallel to the slot (Figs. 5 and 6, not shown). Instead of employing a skirt as in the arrangements of Figs. 3 to 6 the operative extent of the radiating surface may be defined by a plurality of fins arranged parallel to the slot, in the case of an elongated slot, or, when the slot is in the form of a cross (Figs. 7 and 8, not shown), by a plurality of circular circumferential fins. In the arrangement of Fig. 9, the operative extent of the radiating surface 33, underlying a main metallic surface 34, is determined, because of aerodynamic considerations, by the opening 35 in the latter surface. The opening may contain a non-conductive protective material to effect streamlining and to shield the surface # 33. In the arrangement of Fig. 10 a - slot 36 2 A is fed at points 38 ... 40, and a - slot 37 mid- 4 way of and at right angles to the slot 36 effectively separates the portions 42, 43 thereof so that the latter portions function as separate slot aerials. In a further arrangement (Fig. 11, not shown) two cross-shaped slots are formed in the surface of a conducting cylinder and the desired operative extent of the surface is determined by suitably-positioned impedance slits.