An array antenna feed system which provides a constant beamwidth over a large bandwidth of operating frequencies. In transmitter applications, the applied signal is divided into correction and basic signals by a frequency sensitive splitter. The magnitudes of the basic and correction signals provided by the splitter vary sinusoidally with frequency and are displaced a quarter cycle from each other on the frequency scale. The correction and basic signals are combined in series or corporate coupler arrays to drive the individual antenna elements. Coupler coefficients are predetermined to make the complex addition of the correction and basic signals provide a resulting synthesized signal which gives the desired voltage distribution for the same beamwidth at the operating frequency limits. In receiving applications, the splitter functions to combine the correction and basic signals from the coupler array and transfer a combined signal to the receiver circuitry.

A distributive beam steering computer network for a radar phased array antenna is disclosed which provides direct drive for individual antenna phase shifter elements using a plurality of microcomputers co-located with each phase shifter. The microcomputers calculate the phase shift based on constants stored in a ROM which is located in each microcomputer and phase shift data comprising sin .alpha., sin .beta., and 1/.lambda. signals are distributed to all microcomputers over a single serial data line. The constants required for each shifter are different, and therefore, the ROM in each microcomputer is programmed for a specific location in an array antenna. A phase shift steering command for each element of the phased array antenna is calculated using a shift-and-add multiplication algorithm which is hard-wired into each microcomputer.

A feed device for a sweep beam array antenna which has a plurality of elementary antennae combined into a plurality of sub-arrays having a predetermined overlap at their ends. Each sub-array includes a plurality of elementary groups, each elementary group including N elementary antennae. Each elementary group is fed by a feed circuit having N inputs and N outputs. Circuitry is provided for grouping together an arbitrary number of said elementary groups to form an assembly comprising MN elementary antennae, where M is greater than N, and MN antennae are the number of antennae in a sub-array. This circuitry is connected to an energy distributor and includes a plurality of divider distributor circuits, each one coupled to an output of the energy distributor. Each divider distributor circuits has M outputs. The circuitry also includes a plurality of adder distributor circuits, each one having N outputs coupled to the N inputs of a respective one of said elementary groups. Each adder distributor circuit has M inputs which are coupled to the M outputs of predetermined ones of the divider distributor circuits according to a predetermined, periodic law.

A monopulse antenna array arrangement includes a transmit-receive processor (TR Proc) associated with each antenna element. Each TR Proc has a port associated with the radiating element and at least two further ports, one for a sum beamformer and another for a difference beamformer. Within each TR Proc, a switching arrangement allows transmitter signal to flow through a phase shifter and transmit amp during transmission, and allows received signal to flow through a low-noise amp and the same phase shifter on reception. Each TR Proc includes a coupling arrangement with a second phase shifter and a second output port, adapted to be coupled to a difference beamformer during reception.

A method for steering a beam of an antenna array minimizes a least squares approximation of an error function of a desired radiation pattern relative to an antenna array pattern calculated from a known radiation pattern for each antenna element.