GB1352670A - Antenna array - Google Patents

Abstract

1352670 Aerials; radio navigation STANDARD TELEPHONES & CABLES Ltd 26 Oct 1972 49455/72 Headings H4A and H4D An aerial arrangement comprises a linear array of N radiator elements, means for exciting N - 1 of said elements in turn, the remaining element being located at one end of the array, means for short-circuiting each of said N elements, means for open-circuiting each of said N - 1 elements, and means for operating the aforesaid means so that when any element is excited the adjacent element towards said one end is short-circuited, whilst the remainder of the said N - 1 elements are open circuited. As described, the array is constituted by nine monopoles E1 to E9 with #/4 spacings (# = wavelength at the operating frequency). The elements E2 to E9 are connected by respective transmission lines T2 to T9 to a commutator C, and each of said lines is provided with two shunt PIN diodes, such as D31 and D32 for the line T3, which are, respectively, an even- and an odd-multiple of #/4 from the base of the element. Selective biasing means enable any diode to provide either an open- or a short-circuit. Thus, when an "outer" diode, such as D31, is biased on, the resulting short-circuit is transformed to short-circuit the base of the associated element, e.g. E3, which is then available as a parasitic reflector for the element E4. When an inner diode is biased on, the resulting short-circuit is transformed to open-circuit the base of the associated element, which is thereby rendered virtually transparent to radiation from any other element. When both diodes of a transmission line are biased off, the associated element will radiate if excited by the commutator. The base of the element E1 may be shortcircuited via a #/2 length of transmission line, to which earth is either permanently connected, or is connected by a switching diode when required. The arrangement enables a substantially identical radiation pattern to be obtained from each element as it is excited in turn.