Direction finding system using body-worn antenna

• US 6,771,224 B2
• Filed: 07/03/2002
• Issued: 08/03/2004
• Est. Priority Date: 07/03/2002
• Status: Expired due to Fees

• Current Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Original Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Inventors: Apostolos, John T.
• Primary Examiner(s): Vannucci, James
• Application Number:
  US10/190,020
• Publication Number:
  US 20040004573A1
• Time in Patent Office: 762 Days
• Field of Search: 343/718, 343/868, 343/700.MS
• US Class Current: 343/718
• CPC Class Codes: G01S 3/023 Monitoring or calibrating
• CPC Class Codes: G01S 3/14 Systems for determining direction or deviation from predetermined direction aerial arrangements for changing or varying the orientation or the shape of the directional pattern H01Q3/00; combinations of different interacting aerial units for giving a desired directional characteristic H01Q21/29; aerials or aerial systems providing at least two radiation patterns H01Q25/00
• CPC Class Codes: G01S 5/04 Position of source determined by a plurality of spaced direction-finders
• CPC Class Codes: H01Q 1/273 Adaptation for carrying or wearing by persons or animals
• CPC Class Codes: H01Q 11/14 with parts bent, folded, shaped or screened or with phasing impedances, to obtain desired phase relation of radiation from selected sections of the antenna or to obtain desired polarisation effect H01Q11/20 takes precedence

Abstract

Body-worn antennas operate in combination with a direction finding processor to be able to detect the presence of electromagnetic radiation involved in communication as well as the direction of the source of the electromagnetic radiation. In one embodiment, a number of wide bandwidth antennas, 2 MHz to 40 GHz, are incorporated into a body-worn vest or garment such that an individual wearing the vest is being provided with a wearable system for indicating the direction of the source of incoming signals. If the orientation and geographic location of the individual are known via the use of a compass and/or by GPS receiver, the source of the radiation can be pinpointed by triangulation with inputs from other body-worn units. For omni-directional detection, pairs of antennas are provided with feed points or spigots which are fed in phase. Once an incoming source of electromagnetic radiation is detected, a direction finding analysis is conducted by sampling the spigots separately and proceeding with correlation interferometric direction finding. For troops in the field or police officers, the bearing of the source is most useful in knowing where the enemy or perpetrator is. In a preferred embodiment, each of the antennas is a meander line loaded antenna, in which the meander line loaded antennas are provided with a virtual ground plane passing through the body of the individual wearing the antennas. In order to provide the virtual ground plane, the antennas on the front of the vest provided are provided with corresponding duplicate meander line loaded antennas on the back of the vest. Meander line antennas are utilized due to their wide bandwidth performance, with the conductive plates in one embodiment being flexible conductive fabric. Depending on the processing of the outputs from the antennas on the vest or other garment, the system will work either with the individual in a standing mode or when the wearer is lying prone on the ground.

Claims

1. A man portable system for finding the direction of a source of electromagnetic radiation, comprising:

a garment to be worn by an individual;

direction finding antennas carried by said garment, each of said direction finding antennas including a meander line loaded antenna, each meander line loaded antenna having one plate on the front of said garment and having a ground plane plate on the rear of said garment, said front and rear plates having meander lines coupling respective plates together to form a virtual ground plane that runs through said individual when said garment is worn, said virtual ground plane completing each of said meander line loaded antennas; and

,

a direction finding module connected to said direction-finding antennas for determining the bearing of said source to said individual.

2. The system of claim 1, and further including a bearing line indicator coupled to said direction finding module for indicating the bearing of said source to said individual.

3. The system of claim 2, wherein said bearing line indicator includes circumferentially arrayed indicators and means for activating the indicator closest to said bearing line.

4. The system of claim 3, wherein said circumferentially arrayed indicators include vibrating devices.

5. The system of claim 4, wherein said direction finding antennas have a wide bandwidth to permit detection of electromagnetic radiation over a wide band of frequencies.

6. The system of claim 5, wherein said direction finding antennas include meander line loaded antennas.

7. The system of claim 6, wherein the frequency range of said direction-finding antennas is between 2 MHz and 40 GHz.

8. The system of claim 7, wherein each of said direction finding antennas each one plate on the front of said garment and have a virtual ground plane formed by a plate on the rear of said garment, said front and rear plates having meander lines which couple respective plates together to form a virtual ground plane that runs through said individual when said garment is worn, said virtual ground plane completing each of said meander line loaded antennas.

9. The system of claim 1, wherein each of said direction finding antennas includes a side plate and a meander line coupling said front plate to said side plate.

10. The system of claim 9, wherein corresponding front and rear plates utilize the same side plate.

11. The system of claim 10, wherein the corresponding front and rear plates, side plate and meander lines are identical, thus to form said virtual ground plane between said front and rear plates.

12. A wearable set of direction finding antennas, comprising:

a front meander line loaded antenna embedded in a garment to be worn by an individual and positioned on the front of said individual, said front antenna having a plate and a meander line coupled thereto at one end thereof;

a corresponding back meander line antenna on the back of said individual and configured to provide said front antenna with a virtual ground plane that runs at least partially through the body of said individual to complete the antenna on the front of said individual; and

,

a side plate coupled to the other end of said meander line and to the back antenna, said front and back antennas being electrically identical and connected together through said side plate.

13. The antennas of claim 12, and further including an array of four of said antennas on the front of said garment and four of said antennas on the back of said garment.

14. The antennas of claim 13, and further including a direction finding module coupled to pairs of said antennas, said module storing a set of outputs for said antennas generated by a transmission from an electromagnetic source, said set of outputs corresponding to measurements taken at angular increments for selected frequencies, and a correlator for correlating the outputs of said antennas to stored data to produce an output describing the bearing to a source of electromagnetic radiation.

15. A body wearable direction finding system, comprising:

an array of meander line loaded direction finding antennas on the front of an individual, each complete save for a ground plane component to run through the center of said individual;

a corresponding array of direction finding antennas on the back of said individual, each complete save for a virtual ground plane component to run through the center of said individual;

coupling means for connecting corresponding front and back antennas together to form a virtual ground plane usable by both said front and back antennas, whereby a physical ground plane need not be placed through the body of said individual; and

,

a direction finding module coupled to the outputs of said antennas for producing a signal representing the bearing line from a source of electromagnetic radiation to said individual.

16. The system of claim 15, wherein said direction finding antennas include loaded meander lines, said antennas having a wide bandwidth provided thereby.

17. The system of claim 15, and further including a signal processing module interposed between said direction finding antennas and said direction finding module for weeding out signals from selected sources, whereby the output of said direction finding module is only responsive to predetermined sources of electromagnetic signals.