Dual beam monopulse antenna system

• US 6,169,518 B1
• Filed: 06/12/1980
• Issued: 01/02/2001
• Est. Priority Date: 06/12/1980
• Status: Expired due to Term

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Flick, Edward A., Nelson, Everett A.
• Primary Examiner(s): Blum, Theodore M.
• Application Number:
  US06/158,817
• Time in Patent Office: 7,509 Days
• Field of Search: 343/100.SA, 343/854, 343/895, 343/777, 343/778, 343/768, 343/16.M, 343/16.LS, 342/373, 342/149
• US Class Current: 342/373
• CPC Class Codes: G01S 13/44 Monopulse radar, i.e. simultaneous lobing
• CPC Class Codes: G01S 13/4409 HF sub-systems particularly adapted therefor, e.g. circuits for signal combination multi-lobing aerials or aerial systems H01Q25/00
• CPC Class Codes: G01S 7/02 of systems according to group G01S13/00
• CPC Class Codes: G01S 7/03 Details of HF subsystems specially adapted therefor, e.g. common to transmitter and receiver
• CPC Class Codes: H01Q 21/005 Slotted waveguides arrays
• CPC Class Codes: H01Q 25/002 providing at least two patterns of different beamwidth; Variable beamwidth antennas
• CPC Class Codes: H01Q 25/02 providing sum and difference patterns H01Q25/04 takes precedence
• CPC Class Codes: H01Q 3/08 for varying two co-ordinates of the orientation
• CPC Class Codes: H01Q 3/24 varying the orientation by switching energy from one active radiating element to another, e.g. for beam switching

Abstract

A dual beam monopulse antenna system includes a flat plate antenna (10). The antenna (10) comprises a plurality of slotted waveguides (20) which transmit radiation through slots (28). The antenna is divided into quadrants (12, 14, 16, 18) for monopulse operation. Each of the quadrants is provided with primary and secondary feed lines which are connected through directional couplers (42-136) to connecting lines (146-192) to the slotted waveguides (20). The primary feed lines (26, 28, 30, 32) are connected to a primary monopulse comparator network and the secondary feed lines (34, 36, 38, 40) are connected to a secondary monopulse comparator network. The summation terminals of the monopulse comparator networks are connected to a switch network (322). The azimuth differential terminals of the monopulse comparator networks are connected to a switch network (332). The elevation differential terminals of the monopulse comparator networks are connected to a switch network (342). The switch networks are set to a first state to generate a pencil beam in which the slotted waveguides (20) are connected to the system summation terminal (330), system azimuth terminal (340) and system elevation terminal (350). In a second state the switch networks are set such that the slotted waveguides (20) are connected to both the primary and secondary feed assemblies and therefore to the primary and secondary monopulse comparator networks. In the second state the slotted waveguides (20) produce a shaped search beam which has a greater vertical dimension than horizontal dimension. The antenna system, however, operates in the monopulse mode with both antenna beams. The system can be rapidly switched from one beam shape to the other. Polarization discs (458, 460) are positioned parallel to and spaced apart from antenna (10) to select a polarization desired for the beam produced by the antenna system by rotation of the polarization disc (458, 460).

Claims

1. A dual beam monopulse antenna system comprising:

an array of slotted waveguides arranged in a plurality of groups;

a primary feed assembly for each group of said slotted waveguides, the primary feed assembly coupled to the slotted waveguides in the corresponding group;

a secondary feed assembly for each group of said slotted waveguides, the secondary feed assembly coupled to both the slotted waveguides and the primary feed assembly for the corresponding group;

a primary monopulse network connected to said primary feed assemblies and having a summation terminal, a first difference terminal and a second difference terminal;

a secondary monopulse network connected to said secondary feed assemblies and having a summation terminal, a first difference terminal and a second difference terminal;

means for coupling a system summation terminal to either the primary monopulse network summation terminal or to both the primary and the secondary monopulse network summation terminals;

means for coupling a system first difference terminal to either the primary monopulse network first difference terminal or to both the primary and the secondary monopulse network first difference terminals; and

means for coupling a system second difference terminal to either the primary monopulse network second difference terminal or to both the primary and the secondary monopulse network second difference terminals.

2. The antenna system recited in claim 1 wherein said primary feed assembly comprises a primary feed line, a plurality of directional couplers connected to said primary feed line and connecting lines joining the directional couplers to said slotted waveguides, and said secondary feed assembly comprises a secondary feed line, a plurality of directional couplers connected to both said secondary feed line and respectively to the directional couplers connected to said primary feed line.

3. The antenna system recited in claim 2 wherein said first monopulse network comprises:

a first hybrid connected to two of said primary feed lines and having a first hybrid summation terminal and a first hybrid difference terminal;

a second hybrid connected to the remaining two of said primary feed lines and having a second hybrid summation terminal and a second hybrid difference terminal;

a third hybrid connected to the first and second hybrid difference terminals and having a third hybrid summation terminal which corresponds to said first monopulse network first difference terminal and a terminated third hybrid difference terminal; and

a fourth hybrid connected to said first and second hybrid summation terminals and having a fourth hybrid difference terminal which corresponds to said first monopulse network second difference terminal and a fourth hybrid summation terminal corresponding to said first monopulse network summation terminal.

4. The antenna system recited in claim 2 wherein said second monopulse network comprises:

a first hybrid connected to two of said secondary feed lines and having a first hybrid summation terminal and a first hybrid difference terminal;

a second hybrid connected to the remaining two of said secondary feed lines and having a second hybrid summation terminal and a second hybrid difference terminal;

a third hybrid connected to the first and second hybrid difference terminals and having a third hybrid summation terminal which corresponds to said second monopulse network first difference terminal and a terminated third hybrid difference terminal; and

a fourth hybrid connected to said first and second hybrid summation terminals and having a fourth hybrid difference terminal which corresponds to said second monopulse network second difference terminal and a fourth hybrid summation terminal which corresponds to said second monopulse network summation terminal.

5. The antenna system recited in claim 2 wherein the directional couplers connected to said primary feed line have respective coupling parameters to form a pencil-shape beam from the slotted waveguides.

6. The antenna system recited in claim 2 wherein the directional couplers connected to said primary and secondary feed lines have respective coupling parameters to form from said slotted waveguides a beam having a greater angular dimension in a selected plane than in a plane orthogonal thereto.

7. The antenna system recited in claim 1 wherein each of said means for coupling comprises a two state, four port circulator and a directional coupler, said circulator having a first port connected to one of the terminals of said first monopulse network, a second port connected to one of said system terminals, a third port connected to a first port of said directional coupler, and a fourth port connected to a second port of said directional coupler and a third port of said directional coupler connected to one of the terminals of said second monopulse network.

8. The antenna system recited in claim 1 including at least one polarization disc positioned offset from and parallel to said array for controlling the polarization of the beams produced by said antenna system.

9. The antenna system recited in claim 8 wherein said polarization disc comprises a central dielectric having a grid of parallel wires on each face thereof.

10. The antenna system recited in claim 8 including means for rotating said disc about the axis thereof for changing the polarization of the beams produced by said antenna system.

11. A dual beam monopulse antenna system, comprising:

an array of slotted waveguides arranged in a plurality of groups;

a primary feed assembly for each group of slotted waveguides, the primary feed assembly coupled to the slotted waveguides in the corresponding group;

a secondary feed assembly for each group of slotted waveguides, the secondary feed assembly coupled to both the slotted waveguides and the primary feed assembly for the corresponding group;

means connected to the primary and secondary feed assemblies for each group of slotted waveguides for coupling a group terminal to the primary feed assembly in a first state and to both the primary and the secondary feed assemblies in a second state; and

a monopulse network connected to each of said group terminals and having a summation terminal, a first difference terminal and a second difference terminal.

12. The antenna system recited in claim 11 wherein said primary feed assembly comprises a primary feed line, a plurality of directional couplers connected to said primary feed line and connecting lines joining said directional coupler to said slotted waveguides, and said secondary feed assembly comprises a secondary feed line, a plurality of directional couplers connected to both said secondary feed line and respectively to the directional couplers connected to said primary feed line.

13. The antenna system recited in claim 12 wherein the directional couplers connected to said prmary feed line have respective coupling parameters to form a pencil-shape beam from the array of slotted waveguides.

14. The antenna system recited in claim 12 wherein the directional couplers connected to said primary and secondary feed lines have respective coupling parameters to form from said slotted waveguides a beam having a greater angular dimension in a selected plane than in a plane orthogonal thereto.

15. The antenna system recited in claim 11 wherein said monopulse network comprises:

a first hybrid connected to two of said group terminals and having a first hybrid summation terminal and a first hybrid difference terminal;

a second hybrid connected to the remaining two of said group terminals and having a second hybrid summation terminal and a second hybrid difference terminal;

a third hybrid connected to the first and second hybrid difference terminals and having a third hybrid difference terminal which corresponds to said monopulse network first difference terminal and a terminated difference terminal; and

a fourth hybrid connected to the first and second hybrid summation terminals and having fourth hybrid difference terminal which corresponds to said monopulse network second difference terminal and a fourth hybrid summation terminal which corresponds to said monopulse network summation terminal.

16. The antenna system recited in claim 11 wherein said means for coupling comprises a two state, four port circulator and a directional coupler, said circulator having a first port connected to said primary feed assembly, a second port connected to the group terminal, a third port connected to a first port of said directional coupler and a fourth port connected to a second port of said directional coupler, and a third port of said directional coupler connected to said secondary feed assembly.

17. The antenna system recited in claim 11 including at least one polarization disc positioned offset from and parallel to said array for controlling the polarization of the beams produced by said antenna system.

18. The antenna system recited in claim 17 wherein said polarization disc comprises a central dielectric having a grid of parallel wires on each face thereof.

19. The antenna system recited in claim 17 including means for rotating said disc about the axis thereof for changing the polarization of the beams produced by said antenna system.