US 4,989,011 A · Dual mode phased array antenna system

Abstract

A phased array antenna system (20; 120) having an array (22; 122) of radiating elements (24-30; H1-H32), such as pyramidal horns, and a distribution network (32; 124) connected thereto, has a dual mode of operation where each mode produces a composite beam which can and preferably does produce an identical far-field electromagnetic radiation pattern. The first composite beam is made up of a plurality of individual beams, forming a linear combination of excitation coefficients (a.sub.1 -a.sub.4) that are mathematically orthogonal to the linear combination of excitation coefficients (b.sub.1 -b.sub.4) of the individual beams of the other composite beam. A plurality of input ports (42-44; 176-178) are provided, and each composite beam is associated with an information-bearing input signal applied to one of the input ports. The distribution network (32; 124) is preferably constructed with at least two stages of signal-dividing devices (52-58; 222-228, 270-282) such as directional couplers and at least a pair of phase-shifting devices (60-62; 230-232, 284-296). By using passive devices, the distribution network (32; 124) is substantially lossless and reciprocal, and can thus also be used for dual mode reception of two distinct beams.

Claims17

Dependent claims

A direct-radiating array antenna system comprising:

an array of radiating elements arranged to transmit electromagnetic radiation;
and
distribution network means, having a plurality of input ports and a plurality of output ports connected to the radiating elements, for distributing a plurality of distinct electromagnetic input signals applied to the input ports in a predetermined manner to the output ports such that at least two distinguishable, independent composite beams of electromagnetic radiation having substantially the same far-field radiation pattern emanate from the radiating elements, wherein a first linear combination of individual beams emanating from the array of radiating elements together form a first one of the composite beams, and a second linear combination of individual beams emanating from the array of radiating elements together form a second one of the composite beams, the signals distributed to said output ports being defined by first and second sets thereof respectively associated with said two composite beams, wherein the signals in each of the sets thereof possess a preselected distribution of differing amplitudes and the distributions of amplitudes are essentially mirror images of each other.

A direct receiving array antenna system for receiving a portion of each of at least two composite beams of electromagnetic radiation emanating from essentially coextensive far field radiating areas, being in the same general frequency range and having the same polarization, comprising:

a plurality of elements each arranged for receiving a portion of each of the beams;
and
network means, having a plurality of first ports connected to the elements and a plurality of second ports, for separating the two composite beams received by the elements into at least two distinct signals which are respectively output on distinct ones of the second ports, with each such distinct signal being derived from a distinct one of the beams, the plurality of array elements receiving a first linear combination of individual beams defining one of the two composite beams and receiving a second linear combination of individual beams defining the other of the two composite beams, the network means being responsive to the first and second linear combinations of individual beams to respectively produce first and second sets of signals at the first ports, wherein the signals in each of the sets thereof possess a preselected distribution of differing amplitudes and the distributions of amplitudes are essentially mirror images of each other.

Dependencies are inferred from the claim text.

Dual mode phased array antenna system

Life of this patent

Dual mode phased array antenna system

Life of this patent

Abstract

Claims17