GB1341543A - - Google Patents

Abstract

1341543 Aerials INTERNATIONAL STANDARD ELECTRIC CORP 14 Sept 1972 [17 Sept 1971] 42624/72 Heading H4A An aerial scanning arrangement comprises an array of aerial elements each of which is associated with a mixing means for coupling signals of respective frequencies (f 0 +f s ), (f 0 -f s ), where f 0 is fixed, and f s is a variable steering frequency. A phase shift means has a respective terminal associated with each mixing means and provides progressive phase shifts in one of said coupled signals. A first means receives signals at the frequencies f 0 , f s , and couples one of the signals of frequencies (f 0 +f s ), (f 0 -f s ) to or from said phase shift means, and couples the other to the mixing means. In a first embodiment, a linear array of monopoles or dipoles is provided with scanning in azimuth. The phase shift means is a delay line which is fed at one end, and is tapped at regular intervals for connection to successive mixing means (Fig. 1A not shown). In a second embodiment, a twodimensional aerial array is made up of rows and columns of radiators 19, Fig. 2A, each radiator being coupled to a respective mixer 18. A secondary delay line 16 is associated with each column of radiators, taps being taken therefrom at regular intervals to successive radiators in said column. A primary delay line 6 is tapped at regular intervals to feed successive secondary delay lines 16. A signal of fixed frequency f 0 is generated by a prime oscillator 1, and a signal of variable frequency f s is generated by a steering oscillator 2, and both signals are fed as inputs to a mixer 3. An output of frequency (f 0 +f s ) from the mixer 3 is fed to one input of each mixer 18 and, in the transmit mode, the other output of frequency (f 0 -f s ) from the mixer 3 is fed via a switch SW to the input of the delay line 6. The output from each mixer 18 to the associated radiator 19 is of frequency 2f 0 , and it has a relative phase made up of an azimuthal component which is determined by the spacing between taps on the delay line 6, and an elevation component which is determined by the spacing between taps on the delay lines 16. The spacing between taps on the delay line 6 is considerably more than the spacing between taps on the delay lines 16 and, consequently, as the frequency f s is raised the beam from the array is rapidly scanned in azimuth, is then succeeded by another beam at somewhat higher elevation, which is likewise rapidly scanned in azimuth, and so on. A raster like scanning pattern is thus produced. In the receive mode, the switch SW is operated so that the end of the delay line is connected to one input of a mixer 13. Said mixer also receives an input of frequency f s from the oscillator 2, and it provides an output of frequency f 0 for receiving equipment.