GB1482263A - Linearly polarized phased antenna array - Google Patents

Abstract

1482263 Phase shifters INTERNATIONAL STANDARD ELECTRIC CORP 19 July 1974 [31 July 1973] 32073/74 Heading H1W [Also in Division H4] The Specification describes a linearly polarized phased antenna array employing a symmetrically disposed array of linearly polarized dipole elements mounted on a printed circuit board and fed by a balanced power distribution network, the circuitry employed being known as "mat-strip", which is defined as a photoetched or printed balanced transmission line printed on opposite sides of a P.C. board so that both conductors are superimposed, are equal in width and equal in length, each conductor feeding one wing only of the dipole to which it is connected. The antenna array further comprises a ground plane superimposed by the dipole elements and a phase shifting arrangement selectively coupled to the distribution network to control the angular direction of the linearly polarized antenna beam. In Fig. 2, energy from TX/RX 16 is coupled via waveguide 14 and coaxial line 17, to the mat-strip distribution networks 7 mounted on surfaces 5 and 6 of dielectric sheet 1, by means of a balun 13, which comprises line 17, the inner conductor 18 of which extends through sheet 1 for electrical contact with strip conductor 19, and the outer conductor 20 of which is connected to strip conductor 21, on the underside of sheet 1, having dimensions (Fig. 1) larger than conductor 19, to provide the necessary impedance transition for the required balanced loading. The dipole elements are arranged in symmetrical arrayed groups (Fig. 1) and are fed, in parallel, in groups by distribution network strips 8, 9, which have varying cross-sections over a quarter wavelength at junctions for matching purposes. Each dipole element 2 comprises a wing 3 disposed on the lower surface 5 of sheet 1, and wing 4 on upper surface 6. The phase shifter 22 for each dipole comprises quarter wavelength impedance transformer to which is coupled shunt mat-strip transmission lines 27 and 28. PIN switching diodes 23 and 24 arranged to lie flush with the strip conductors, switch lines 27 and 28 into radio frequency grounding and direct current biasing pads 31 and 32. The diodes are controlled by switching voltage source 35. When a radio frequency ground is applied to lines 27 and 28, R.F. passes through the D.C. biasing conductors and is earthed via by-pass capacitors (38) mounted on ground plane 10, a 45 degree phase shift is provided in the R.F. coupled to elements 2 enabling angular direction control of the antenna beam. The ground plane 10, is provided by the mounting for the dielectric sheet 1, which may be of Z-tron, Tellite, "Rexilite" (Registered Trade Mark) or "Duroid" (Registered Trade Mark), plane 10 being spaced therefrom by a quarter wavelength. In another embodiment, Fig. 5, two dipole wings per element are provided on each dielectric surface and each is connected to the distribution conductor via a PIN switching diode. By switching between pairs of diagonally opposed wings, a 180 degree phase shift may be introduced in to the beam from each dipole element. Several phase shifters 22, 22a, 22b may be provided so that the signal fed to each dipole may be phase shifted in increasing increments of 45 degrees.