Frequency dispersive transmitting array

Abstract

A Frequency Dispersive Transmitting Array (30) for propagating composite e energy (10) emulates narrow-band beams (20) of different frequencies which can be simultaneously radiated in all directions, or in any subset of directions, relative to an array (42) of radiating elements (32) because of the addition and cancellation of components of wave energy (10) radiated, is disclosed. A signal source (34) provides input signals (36), having frequencies which may be acoustic or electromagnetic, which are coupled by feedline (37) to radiating elements (32) through a plurality of time delay devices (38). Each one of time delay devices (38) is interposed between successive ones of radiating elements (32) and delays emission of replicas of signals (36) therefrom by a time delay .tau..sub.0 which is a multiple of the period of the dominant frequency radiated in a direction broadside to the array. Window weighting function devices (40) are coupled into feedline (37) modifying signals (36) ahead of radiating elements (32) to control the behavior of side lobes of the beam as in a conventional beam-forming array. Frequency dispersion of the beams (20) is controlled by selection of the bandwidth of input signals (36) having frequencies in a desired spectrum depending on the use of the system. Direction (.theta.) of an object from transmitting array (30) is determinable from the frequency of wave energy (10) either directly received at the object or reflected by the object to a remote receiver, because each direction (.theta.) corresponds to a distinct frequency (f) of transmitted wave energy (10).