GB1481175A - Circularly polarized phased antenna array - Google Patents

Abstract

1481175 Aerials; aerial feeds INTERNATIONAL STANDARD ELECTRIC CORP 19 July 1974 [25 July 1973] 32072/74 Heading H4A An antenna array which is arranged to produce an antenna beam from a single aperture having either one or both of left-handed or right-handed circular polarization by modifying the antenna array described in Application No. 32073/74, so that the linearly polarized beam produced thereby passes through a transmission polarizer to impart circular polarization thereto. In the Fig. 1 embodiment, a dielectric sheet 1 comprising one entenna array, is stacked above a second dielectric sheet 12, and is disposed at right angles thereto. Metallic housing 13 provides a ground plane spaced at a quarter wavelength from sheet 12, while the ground plane spaced from sheet 1 is provided by an interposed dielectric sheet 14 having disposed thereon metallic strips 15 which are oriented to be parallel to and superimposed by the dipole elements of the top-most linearly polarized phase antenna array on sheet 1 (see Fig. 1). The linearly orthogonally polarized antenna beams from sheets 1 and 12 are respectively converted to right and left handed circular polarization by a common polarizer comprising dielectric sheet 16 having disposed thereon a plurality of printed spaced conductive polarizers 17 shown as meander lines, but may also comprise a system of bars, or printed straight conductors or variable dielectric constant stubs, separation between the sheets may be maintained by bolts 18 and spacers 19, 20, &c., or by low density foam. In other embodiments variations in the disposition of the ground planes are described. In Fig. 7 (not shown) sheet 14 is disposed between metallic housing 13 and sheet 12. In Fig. 8 (not shown) sheet 14 is eliminated, and spaced conductive strips are mounted on housing 13 to provide a ground plane for sheet 1. In Fig. 9 (not shown), the phased array mounted on sheet 12 operating at around 8 GHz provides a ground plane for sheet 1 operating at around 200 MHz.