Frequency dispersive transmitting array

• US 5,150,336 A
• Filed: 09/03/1991
• Issued: 09/22/1992
• Est. Priority Date: 09/03/1991
• Status: Expired due to Fees

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Gordon, Frank E., Sullivan, Shelby F., Castile, Brett D.
• Primary Examiner(s): Pihulic, Daniel T.
• Application Number:
  US07/758,994
• Time in Patent Office: 385 Days
• Field of Search: 367/103, 342/375
• US Class Current: 367/103
• CPC Class Codes: G01S 13/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S13/46
• CPC Class Codes: G01S 13/933 of aircraft or spacecraft
• CPC Class Codes: G01S 15/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S15/46
• CPC Class Codes: G01S 5/20 Position of source determined by a plurality of spaced direction-finders
• CPC Class Codes: G10K 11/341 Circuits therefor
• CPC Class Codes: H01Q 3/22 varying the orientation in accordance with variation of frequency of radiated wave
• CPC Class Codes: H01Q 3/2688 using acoustic or magnetostatic wave devices

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 τ₀ 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 (θ) 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 (θ) corresponds to a distinct frequency (f) of transmitted wave energy (10).

Claims

1. An apparatus for propagating composite wave energy comprised of a plurality of components each having a frequency of wave motion which is a function of a direction in which each of said components is propagated, comprising:

radiating means for radiating said composite wave energy, said radiating means having a plurality of radiating elements comprising an array;

signal-generating means for generating broad-band signals in a selected band of frequencies;

time-delay means for providing a time delay between the emission of said broad-band signals from each successive one of said plurality of said radiating elements, said time-delay means being coupled between successive ones of said plurality of said radiating elements and having a delay time which is a multiple of the period of the dominant frequency radiated in a direction broadside to said array;

said array having a radiation pattern;

said signal-generating means being coupled to and driving said radiating means through said time delay means; and

window weighting function means for controlling the behavior of said radiation pattern of said array, said window weighting function means being coupled between said signal generating means and each of said radiating elements.

2. The apparatus of claim 1 wherein said radiating elements are arranged uniformly in said array.

3. An apparatus as claimed in claim 1 in which said composite wave energy emulates a plurality of simultaneously-radiated narrow-band beams, each one of said emulated narrow-band beams being radiated in a direction and each having a different center frequency.

4. An apparatus as claimed in claim 3 in which said direction of each said emulated narrow-band beam corresponds to an angle between -90°

and +90°

from a broadside direction to said array.

5. An apparatus as claimed in claim 1 in which said composite wave energy has the characteristics of sound.

6. An apparatus as claimed in claim 5 in which said radiating elements comprise acoustic radiators.

7. An apparatus as claimed in claim 1 in which the said propagating composite wave energy has the characteristics of electromagnetic radiation.

8. An apparatus as claimed in claim 7 in which said radiating elements comprise electromagnetic radiators.

9. An apparatus as claimed in claim 1 in which said time-delay means comprises a plurality of L-C circuits.

10. An apparatus as claimed in claim 1 in which said time-delay means comprises a plurality of delay-line circuits.

11. An apparatus as claimed in claim 1 in which said time-delay means comprises a plurality of serpentine feedlines.

12. A frequency dispersive beam forming apparatus for transmitting a radiation pattern of composite wave energy having the characteristics of a plurality of narrow-band beams, each of said narrow-band beams having a center frequency which is a function of a direction in which each of said narrow-band beams is propagated, comprising:

a signal source having an output of broad-band signals in a selected band of frequencies;

a transmitting array having a plurality of radiating elements;

a plurality of time-delay devices, each of said time-delay devices having a delay time which is a multiple of the period of the dominant frequency radiated from a direction broadside to said array, each of said time-delay devices being coupled between successive ones of said plurality of said radiating elements;

said array having a radiation pattern characterized by a plurality of main lobes and of sidelobes;

said signal source being coupled to each of said radiating elements of said transmitting array through said time-delay devices by a feedline; and

a plurality of window weighting function devices each of said window weighting devices being coupled between said signal source and one of said radiating elements by said feedline.

13. An apparatus as claimed in claim 12 wherein said radiating elements are uniformly arranged in said array.

14. An apparatus as claimed in claim 12 in which said main lobes of each of said narrow-band beams have a direction corresponding to an angle between -90°

and +90°

from a broadside direction to said array.

15. An apparatus as claimed in claim 12 in which said selected band of frequencies of said output signals comprises acoustic frequencies.

16. An apparatus as claimed in claim 12 in which said selected band of frequencies of said output signals comprises frequencies in the electro-magnetic spectrum.

17. An apparatus as claimed in claim 12 in which each of said time-delay devices comprises L-C circuit elements.

18. An apparatus as claimed in claim 12 in which each of said time-delay device comprises delay-line circuit elements.

19. An apparatus as claimed in claim 12 in which each of said time-delay devices comprises a serpentine wave guide.

20. A method for propagating composite wave energy comprised of a plurality of components each having a frequency of wave motion which is a function of a direction (θ

) in which each of said components is propagated, comprising the steps of;

providing a transmitting array of radiating elements, said array having a radiation pattern;

generating broad-band signals in a selected band of frequencies;

feeding said broad-band signals be a feedline to each successive one of said plurality of said radiating elements through a time-delay device;

delaying the emission of replicas os faid broad-band signals radiated by each successive one of said radiating elements by a delay time, said delay time being a multiple of the period of the dominant frequency radiated from a direction broadside to said array; and

generating a window weighting function modifying said broad-band signals before emission, thereby controlling the behavior of said radiation pattern of said array.

21. The method of claim 20 wherein said step of generating a window weighting function, modifying said broad-band signals before emission, includes controlling the side lobe envelope and main lobe shape of said radiation pattern of said array.

22. The method of claim 20 wherein said step of generating broad-band signals comprises generating a spectrum of broad-band signals which will radiate composite wave energy in all directions between an angle of -90°

and +90°

from a broadside direction to said array.

23. The method of claim 20 wherein said step of generating braod-band signals comprises generating a spectrum of broad-band signals confined to a subset of frequencies of broad-band signals smaller than the spectrum of broad-band signals which will radiate composite wave energy in all directions between an angle of -90°

and +90°

from a broadside direction to said array.

24. The method of claim 20 wherein said radiating elements are uniformly arranged in said array.

25. A method of emulating a plurality of narrow-band beams radiated simultaneously in all directions from a broadside direction of a transmitting array each of said narrow-band beams having a center frequency corresponding to a direction in which each is emitted, comprising the steps of:

providing a plurality of radiating elements arranged in an array, said array having a radiation pattern characterized by a main lobe and side lobes;

providing broad-band signals to said array in a band of frequencies which will radiate said composite wave energy in all directions between an angle of -90° and

+90°

from a broadside direction to said array;

providing a feedline to each of said radiating elements;

providing a plurality of time-delay devices each of which is disposed in said feedline between successive ones of said plurality of said radiating elements, each of said time-delay devices having a delay time which is a multiple of the period of the dominant frequency radiated in a direction broadside to said array; and

feeding said broad-band signals to each successive one of said radiating elements of said array through said time-delay devices so as to delay emission of said broad-band signals from each said successive one of said radiating elements.

26. The method of claim 25 wherein said radiating elements are arranged uniformly in said array.

27. The method of claim 25 wherein said step of generating broad-band signals comprises generating a spectrum of broad-band signals confined to a subset of frequencies of broad-band signals smaller than the spectrum of broad-band signals which will radiate composite wave energy in all directions between an angle of -90°

and +90°

from a broadside direction to said array.