GB1057489A - Improvements in or relating to aerials - Google Patents

Abstract

1,057,489. Aerials. MARCONI CO. Ltd. Oct. 31, 1963 [Dec. 12, 1962], No. 47010/62. Heading H4A. An aerial consists of two conical members 1, 2 having a common cone axis and spaced apart along the axis with their bases away from one another, a partition member 3 in a plane at right angles to the axis and extending across the space between the members 1, 2, means such as plates 4 associated with one of the members for twisting the plane of polarization of transmitted energy through 90 degrees, and feeder means 6, 7 connected to the conical members whereby when the feeder means is energized waves with mutually perpendicular planes of polarization are transmitted from the aerial, waves of one plane of polarization from between one conical member and the partition 3 and waves of a perpendicular plane of polarization from between the other member and the partition. The phase centres of the mutually perpendicular polarizations are at different heights and by careful choice of dimensions it is possible to make the first zero of the vertically polarized radiation pattern coincide with the second null of the horizontally polarized radiation pattern at a given angle of elevation for example 30 degrees. For elevation coverage of 0-30 degrees the height of the phase centres are #/2 and # for vertical polarization and horizontal polarization respectively. The Figure shows a half sectional view of an embodiment of the aerial which operates against a ground plane (Fig. 1, not shown) to which the lower conical member is connected and in which the plates or vanes 4 are formed by bent diamondshaped plates (Figs. 4-6, not shown) and which are so positioned that they each extend at an angle to radial lines passing through the centre of the cone 2. The feeder is a coaxial feeder having its outer conductor 6 connected to the lower conical member 1 and its inner 7 to the upper member 2. In a further embodiment (Fig. 9, not shown) the feeder has an intermediate tubular conductor between the conductors 6 and 7 and connected to the partition member 3 so that an adjustable power divider may be used to apportion power between the two feeders.