A circuit for generating RF signals for an electronically scanned antenna, said antenna comprising a number of independent radiating elements, said circuit receiving an oscillation signal at an input thereof, and generating a plurality of RF signals equal in number to the number of said plurality of radiating elements, said plurality of RF signals differing from each other in phase and amplitude, said circuit comprising:
- a first power divider (DP) for receiving said oscillating signal at an input thereof, and for generating a plurality of first electrical output signals (S1) at a plurality of outputs thereof, each of said plurality of first electrical output signals (S1) having a precise power ratio relative to said oscillating signal;
- a plurality of electronically controlled phase shifters (SE), respectively connected to receive a different one of said plurality of first electrical output signals (S1) output by said first power divider (DP), each of said plurality of electronically controlled phase shifters (SE) providing a respective time-varying phase shift to each respective one of said plurality of first electrical output signals (S1) responsive to a control signal (SC);
- a Butler-matrix (MB) having a plurality of inputs connected to receive a respective output from a limited number, less than all, of said plurality of electronically controlled phase shifters, said Butler-matrix (MB) having a smaller number of outputs than said number of said plurality of radiating elements;
- a plurality of second power dividers (D1), each second power divider having an input connected to receive an output of a respective one of said plurality of electronically controlled phase shifters (SE) that is not connected to said Butler-matrix (MB), each of said plurality of second power dividers (D1) generating at a plurality of outputs thereof, a plurality of second electrical output signals (S2) such that each of said plurality of second electrical output signals (S2) has a precise power ratio relative to the signal provided at the input of each of said plurality of second power dividers;
- a plurality of fixed phase shifters (SF) respectively connected to said plurality of second power dividers;
- and
- a plurality of power adders (SP), equal in number to said number of said plurality of radiating elements, each of said plurality of power adders having an input connected to receive at least one of the outputs of said Butler-matrix and to receive at least one output of said plurality of fixed phase shifters, each of said plurality of power adders providing at an output thereof, a power adder output signal that is provided to a respective one of said number of radiating elements.