Patent GB-1363861-A (GB)
IPC: H01Q3/38
Filed: 1971-11-26
Abstract: 1363861 Aerials MARCONI CO Ltd 26 Nov 1971 [29 Jan 1971] 3445/71 Heading H4A An electrically variable directional array in which phase changes between elements, or sets of elements, to alter the beam direction, are effected by means including ferrite phase shifters, comprises an additional ferrite phase shifter which is responsive to changes of temperature of at least one set of the aforesaid ferrite phase shifters, and means responsive to phase changes of said additional phase shifter to produce temperature compensating phase changes in the associated at least one set of phase shifters. As described, an aerial system, Fig. 1 (not shown), comprises a primary radiator in the form of an open-ended waveguide which feeds via over overall pyramidal horn to the back of a 7 x 7 array of 49 like horn sections, the front faces of which are co-planar, and the necks of which contain variable ferrite phase shifters. A typical horn section 7, Fig. 2, has a neck 71 in which is a ferrite body member 72, longitudinally traversed by a control wire 73 and an auxiliary compensating wire 74. A conduit LQ, through which water is circulated by a pump, is arranged in good heat exchanging relationship with the body 74. The conduit extends from the outlet of the pump to a first additional ferrite phase shifter (AP1), Fig. 3 (not shown), then in succession to the phase shifters of the outermost horn sections (nos. 1 to 24), then back to the said additional phase shifter, and then to the inlet of a first cooling means (D1). From the outlet of the said cooling means the conduit extends to a second additional ferrite phase shifter (AP2), then in succession to the phase shifters of the horn sections immediately inside the outermost horn sections (nos. 25 to 40), then back to the said additional phase shifter, and then to the inlet of a second cooling means (D2). From the outlet of the said cooling means the conduit extends to a third additional ferrite phase shifter (AP3), then in succession to the phase shifters of the central block of horn sections (nos. 41 to 49), then back to the said additional phase shifter, and then to the inlet of the pump. The conduit is in good heat exchanging relationship with the bodies of the additional phase shifters, which consequently assume temperatures representative of those of the bodies of their associated sets of main phase shifters. As is shown in Fig. 4, the ferrite body 1AP 1 of an additional phase shifter AP1 is in a length of waveguide W, into which R.F. power is fed at one end, and is absorbed by a load L at the other end. Probes P1, P2 located respectively at the input and output ends of the body 1AP1 are connected to the inputs of a phase comparator PD. A. D.C. reference voltage from a source RD and the output of the comparator PD are compared in a comparator C, and output therefrom operates a source MC, which provides compensating current in the control wire 2AP1 of the phase shifter AP1. Output from the comparator C also operates a source 2MC, which provides compensating current in the control wire 74 (Fig. 2) of the associated main phase shifters of the horn sections 1 to 24. A gate G may be provided in radar applications which is only opened to allow operation of the source 2MC during the short interval which elapses between the return of an echo from a target at extreme range, and the transmission of the next pulse (the beam being swung during said interval). Similar circuit arrangements are provided for the other additional phase shifters (AP2), (AP3) and their associated sets of main phase shifters.