Dual mode radio frequency-infrared frequency system

• US 4,477,814 A
• Filed: 08/02/1982
• Issued: 10/16/1984
• Est. Priority Date: 08/02/1982
• Status: Expired due to Fees

• Current Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Original Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Inventors: Brumbaugh, Charles T., Klees, Robert M., Pittenger, Robert L.
• Primary Examiner(s): Lieberman, Eli
• Application Number:
  US06/404,096
• Time in Patent Office: 806 Days
• Field of Search: 343/6 ND, 343/840, 343/725, 343/729, 343/770
• US Class Current: 343/725
• CPC Class Codes: F41G 7/008 Combinations of different guidance systems
• CPC Class Codes: F41G 7/2253 Passive homing systems, i.e. comprising a receiver and do not requiring an active illumination of the target
• CPC Class Codes: F41G 7/2286 using radio waves
• CPC Class Codes: F41G 7/2293 using electromagnetic waves other than radio waves
• CPC Class Codes: H01Q 1/281 Nose antennas
• CPC Class Codes: H01Q 15/0013 said selective devices working as frequency-selective reflecting surfaces, e.g. FSS, dichroic plates, surfaces being partly transmissive and reflective
• CPC Class Codes: H01Q 21/20 the units being spaced along or adjacent to a curvilinear path slotted waveguide arrays H01Q21/005; circularly or helically slotted waveguides H01Q21/0062
• CPC Class Codes: H01Q 5/22 RF wavebands combined with non-RF wavebands, e.g. infrared or optical

Abstract

A combined RF/IR system in which a common surface is used in the dual modes of radiating and absorbing RF energy and of reflecting and focusing IR energy. The common surface is structured, configured, and used as the slotted array antenna for the RF energy and as the primary mirror of a Cassegrain optical subsystem for the IR energy.

Claims

1. A dual mode radio frequency-infrared frequency seeker system, comprising:

a. means for seeking, sensing, radiating and absorbing radio frequency energy, wherein this means is mounted on a gimbal means and includes a radio frequency antenna having a surface; and

b. means for seeking, sensing, reflecting, and focusing infrared frequency energy, wherein this means is also mounted on said gimbal means and includes a Cassegrain infrared frequency optical subsystem having a primary mirror with a surface, and wherein this means is operably associated with and is in coaxial relationship with said means for seeking, sensing, radiating and absorbing radio frequency energy;

and wherein said surface of said radio frequency antenna and said surface of said primary mirror are the same surface and form a surface common to both said means, said surface common to both said means defining a strip line transmission assembly, said strip line assembly including a front ground plane and a rear ground plane and being configured in a parabolic shape and having a stip transmission line disposed between said front ground plane and said rear ground plane.

2. A dual mode radio frequency-infrared frequency seeker system, as set forth in claim 1, wherein said front ground plane has a plurality of slots therethrough such that a slotted array radio frequency antenna is formed.

3. A dual mode radio frequency-infrared frequency seeker system, as set forth in claim 2, wherein said slotted array radio frequency antenna includes:

a. said slots through said front ground plane grouped into quadrants;

b. a monopulse beam focusing network in electrical connection with said quadrants; and

c. delay lines in electrical connection with said monopulse beam forming network.

4. A dual mode radio frequency-infrared frequency seeker system, as set forth in claim 3, wherein only a centrally located portion of said common surface comprises said primary mirror, and wherein some of said plurality of slots in said front ground plane are located within said centrally located portion of said common surface, with these slots covered with an infrared frequency-reflective/radio frequency-transmissive dielectric coating.

5. A dual mode radio frequency-infrared frequency seeker system, as set forth in claim 4, wherein said Cassegrain infrared frequency optical subsystem has a secondary mirror in optical alignment with said primary mirror, and is made of rigid radio frequency transmissive material.

6. A dual mode radio frequency-infrared frequency seeker system, as set forth in claim 5, wherein said secondary mirror has a reflective surface which is covered with the same infrared frequency-reflective/radio frequency-transmissive dielectric coating as covers said slots in said centrally located portion of said common surface.

7. A dual mode radio frequency-infrared frequency seeker system, as set forth in claim 6, wherein said means for seeking, sensing, reflecting, and focusing infrared frequency energy further includes an infrared frequency energy sensor with a rotating off-axis image/objective lens onto which said lens is reflected infrared frequency energy by an afocal system formed by said primary mirror and said secondary mirror.