CIRCULAR ANTENNA ARRAY FOR VEHICULAR DIRECTION FINDING

• US 20140232572A1
• Filed: 02/19/2013
• Published: 08/21/2014
• Est. Priority Date: 02/19/2013
• Status: Active Grant

• Current Assignee: King Fahd University Of Petroleum And Minerals
• Original Assignee: King Fahd University Of Petroleum And Minerals
• Inventors: SHARAWI, MOHAMMAD S., KHAN, FAROOQ SULTAN SULTAN, ALOI, DANIEL N.
• Granted Patent: US 9,082,307 B2
• Time in Patent Office: Days
• US Class Current: 340/993
• CPC Class Codes: G08G 1/123 indicating the position of vehicles, e.g. scheduled vehicles; Managing passenger vehicles circulating according to a fixed timetable, e.g. buses, trains, tramstransmission of navigation instructions to vehicles G08G1/0968
• CPC Class Codes: H01Q 19/24 the primary active element being centre-fed and substantially straight, e.g. H-antenna
• CPC Class Codes: H01Q 21/205 providing an omnidirectional coverage turnstile aerials H01Q21/26
• CPC Class Codes: H01Q 9/16 with feed intermediate between the extremities of the antenna, e.g. centre-fed dipole H01Q9/44 takes precedence
• CPC Class Codes: H01Q 9/44 with a plurality of divergent straight elements, e.g. V-dipole, X-antenna; with a plurality of elements having mutually inclined substantially straight portions combinations of two or more active elements H01Q21/00; turnstile antennas H01Q21/26

Abstract

The circular antenna array for vehicular direction finding applications is a circular disc having a plurality of microstrip antennas radially spaced around the disc at equal angles. In one embodiment, the circular antenna array includes V-shaped antennas, and in another embodiment, the antennas are Yagi antennas. The circular antenna array can operate under two modes, switched and phased, in the 2.45 GHz band with an operating bandwidth of at least 100 MHz. The circular antenna array is configured to be installed in vehicles. Selective transmittal of an RF signal from a key fob generates a response signal from a specific antenna element receiving the RF signal in line with the direction of origin thereof. An LED panel indicates proximity and direction to the vehicle being located.

Claims

1. A circular antenna array for vehicular direction finding applications, comprising:

a circular disc constructed from dielectric material, the disc having a concentric hole of a given diameter, and top and bottom sides; and

a plurality of directional microstrip antennas radially spaced at equal angles around the hole, the plurality of antennas having elements disposed on the top and bottom sides of the disc, the plurality of antenna elements being microstrip elements of conductive material.

2. The circular antenna arrays for vehicular direction finding applications according to claim 1, wherein said plurality of antennas comprises:

a plurality of top arm elements and bottom arm elements;

a plurality of top legs extending radially from the hole, each of the top legs having one of the top arms extending from a distal end of the top leg;

a concentric, circular ground plane formed on the bottom side of said disc;

a plurality of bottom necks extending radially from the circular ground plane, each of the necks having one of the bottom arms extending from a distal end of the bottom neck;

wherein each said antenna includes one of the top legs having one of the top arms extending therefrom, and one of the bottom necks having one of the bottom arms extending therefrom.

3. The circular antenna arrays for vehicular direction finding applications according to claim 2, wherein each said antenna comprises:

one of the top legs having one of the top arms extending at an acute angle with respect to perpendicular of the top leg, forming a V-shaped antenna; and

one of the bottom necks having one of the bottom arms extending at an acute angle with respect to perpendicular of the bottom neck below the V-shaped antenna, the angle of the bottom arm being mirror opposite from the corresponding top arm when viewed from the top of said disc.

4. The circular antenna arrays for vehicular direction finding applications according to claim 3, further comprising a lateral gap separating said top leg and said bottom neck.

5. The circular antenna arrays for vehicular direction finding applications according to claim 2, wherein each said antenna comprises:

one of the top legs having one of the top arms extending at a right angle with respect to perpendicular of the top leg; and

one of the bottom necks having one of the bottom arms extending at a right angle with respect to perpendicular of the top leg, the bottom arm extending 180°

opposite from the top arm.

6. The circular antenna arrays for vehicular direction finding applications according to claim 5, further comprising an elongate director strip disposed on the top side of said disc parallel to the top arm and radially spaced from the top arm, said antenna being a microstrip Yagi antenna.

7. A system for locating vehicles, comprising;

a key fob having;

a key fob housing;

a microwave radio transmitter disposed in the housing for selectively generating an RF beacon signal;

a microwave radio receiver disposed in the housing; and

an LED panel mounted on the housing, the LED panel being connected to the receiver;

a circular antenna array adapted for installation on a vehicle, the circular antenna array having;

a circular disc constructed from dielectric material, the disc having a concentric hole of a given diameter, and top and bottom sides; and

a plurality of directional microstrip antennas radially spaced at equal angles around the hole, the plurality of antennas having elements disposed on the top and bottom sides of the disc, the plurality of antenna elements being microstrip elements of conductive material;

a circuit for determining which of the antennas received the beacon signal from the key fob with the strongest strength, and for transmitting a response signal to the key fob receiver in the direction of the beacon signal from the antenna receiving the beacon signal with the strongest strength, the circuit including;

an electronic rotating switch connected to the antennas, the rotating switch selectively activating each of the antennas one at a time;

a front end circuit connected to the rotating switch, the front end circuit having an amplifier and an analog-to-digital converter for amplifying and conditioning the beacon signal received the antennas for processing;

a demodulator circuit connected to the front end circuit for converting the received beacon signal from a carrier frequency of 2.45 GHz to a basic intermediate frequency (IF) range;

a digital signal processor circuit connected to the demodulator circuit, the digital signal processor circuit having a time delay circuit for estimating arrival time of the received beacon signal and a direction of arrival circuit for estimating direction of the received beacon signal;

wherein reception of the response signal from the circular antenna array activates the LED panel to assist a user in determining user proximity to the vehicle being located.

8. The system for locating vehicles according to claim 7, wherein said plurality of antennas comprises:

a plurality of top arm elements and bottom arm elements;

a plurality of top legs extending radially from the hole, each of the top legs having one of the top arms extending from a distal end of the top leg;

a concentric, circular ground plane formed on the bottom side of said disc;

a plurality of bottom necks extending radially from the circular ground plane, each of the necks having one of the bottom arms extending from a distal end of the bottom neck;

wherein each said antenna includes one of the top legs having one of the top arms extending therefrom, and one of the bottom necks having one of the bottom arms extending therefrom.

9. The system for locating vehicles according to claim 8, wherein each said antenna comprises a V-shaped antenna, the top legs having the top arms extending at an acute angle with respect to perpendicular of the top legs, forming the V-shaped antenna, the bottom necks having the bottom arms extending at an acute angle with respect to perpendicular of the bottom neck below the V-shaped antenna, the angle of the bottom arm being mirror opposite from the corresponding top arm when viewed from the top of said disc.

10. The system for locating vehicles according to claim 9, further comprising a lateral gap separating each said top leg from said corresponding bottom neck.

11. The system for locating vehicles according to claim 8, wherein each antenna comprises a Yagi antenna, the top leg having the top arm extending at a right angle with respect to perpendicular of the top leg, the corresponding bottom neck having the bottom arm extending at a right angle with respect to perpendicular of the top leg, the bottom arm extending 180°

opposite from the top arm.

12. The system for locating vehicles according to claim 11, further comprising an elongate director strip disposed on the top side of said disc parallel to the top arm and radially spaced from the top arm.

13. A method for locating vehicles, comprising the steps of;

providing a key fob having a radio transmitter for generating an RF beacon signal and having an LED panel;

providing a circular antenna array adapted for installation on a vehicle, the circular antenna array comprising;

a circular disc constructed from dielectric material, the disc having a concentric hole of a given diameter, and top and bottom sides; and

a plurality of microstrip antennas radially spaced around the hole at equal angles;

installing the circular antenna array on a vehicle;

transmitting a beacon signal from the key fob;

sequentially switching each of the antennas, in the circular array to connect the signals received at the antennas to a receiver circuit;

processing the received signals to determine the antenna receiving the strongest beacon signal and the direction of the key fob transmitter from the circular antenna array;

transmitting a response signal to the key fob through the antenna receiving the strongest beacon signal; and

activating the LED panel on the key fob in response to receiving the response signal from the circular antenna array to indicate the direction of the vehicle from the key fob.

14. The method for locating vehicles according to claim 13, wherein said beacon signal and said response signal are in the 2.45 GHz frequency band.