HUMAN PRESENCE DETECTOR SUITABLE FOR CONCEALMENT AND USING A SHAPED MICROWAVE BEAM

• US 20120229324A1
• Filed: 03/12/2012
• Published: 09/13/2012
• Est. Priority Date: 03/11/2011
• Status: Active Grant

• Current Assignee: Thomas W. Gow
• Original Assignee: Thomas W. Gow
• Inventors: Gow, Thomas W., Schwarz, Edward L.
• Granted Patent: US 8,912,944 B2
• Time in Patent Office: Days
• US Class Current: 342/27
• CPC Class Codes: G01S 13/04 Systems determining presence of a target based on relative movement of target G01S13/56
• CPC Class Codes: G01S 7/032 Constructional details for solid-state radar subsystems

Abstract

A presence detector unit (PDU) of the type relying on microwave radiation provides a signal indicating movement within a defined space when such movement occurs. A source of microwave radiation within a housing projects a beam of microwave radiation directed through a side of the housing to suffuse at least a portion of the defined space. A detector within the housing senses changes in microwave radiation reflected back toward the detector. An adjustable beam occlusion structure is supported by the housing and blocks a portion of the microwave radiation emanating from the source and through the side of the housing.

Claims

1. A presence detector unit (PDU) of the type relying on microwave radiation, and providing a signal indicating movement within a defined space when such movement occurs, comprising:

a) a housing having an interior space, at least a portion of which is made from material that blocks microwave radiation, and having a first side substantially transparent to microwave radiation;

b) a source of microwave radiation within the housing and forming a beam of microwave radiation directed through the first side;

c) a detector of changes in microwave radiation within the housing; and

d) an adjustable beam occlusion structure (ABOS) supported by the housing and blocking a portion of the microwave radiation emanating from the source and through the first side.

2. The PDU of claim 1, wherein the ABOS comprises at least one shutter movable within the microwave radiation beam.

3. The PDU of claim 2, wherein the shutter has a slot, and further comprising a fastener passing through the slot and attached to the housing.

4. The PDU of claim 3, wherein the shutter has a pair of parallel slots, and a pair of fasteners, each fastener passing though one slot of the shutter and attached to the housing.

5. The PDU of claim 4, including four substantially rectangular shutters arranged around the periphery of the first side, wherein each shutter has a pair of substantially parallel slots, and associated with each shutter, a pair of fasteners, each fastener passing though one slot of two shutters and attached to the housing.

6. The PDU of claim 4, wherein an edge of the shutter within the beam is other than a straight line.

7. The PDU of claim 4, wherein the shutter has an interior opening for allowing passage of the beam.

8. The PDU of claim 1, wherein the housing has a plate transparent to microwave radiation overlaying the first side, and wherein the ABOS comprises a metallic foil adhering to the plate, said metallic foil having an opening within the beam for allowing passage of the beam.

9. The PDU of claim 8, wherein the metallic foil detachably adheres to the plate with an adhesive.

10. The PDU of claim 1 adapted for detecting entry through a door into a space for occupancy, and further comprising:

a) a first wall having an entry area therein;

b) a second wall adjoining the first wall at a point spaced from the entry area;

c) a third wall adjoining the first wall and spaced from the entry area, and placing the entry area between the second and third walls, said third wall supporting the PDU with the beam of microwave radiation directed to pass across the entry area and impinge on the second wall; and

d) beam occlusion material on the second wall blocking passage of microwave radiation emitted by the source through the second wall.

11. The PDU of claim 10, wherein the position of the ABOS creates a narrow beam of microwave radiation.

12. The PDU of claim 10, wherein said beam occlusion material on the second wall comprises at least one of a metal sheet within the wall and metallic paint on the wall.

13. The PDU of claim 1, wherein the ABOS includes on the side thereof facing the microwave source, microwave-absorbent material.

14. The PDU of claim 2 wherein the shutter has on a side, a scale relating shutter position relative to the housing and area covered by the beam.

15. The PDU of claim 14, wherein the scale on the shutter further relates shutter position relative to the housing to the distance of the housing from a floor of the defined space.