Planar antenna

• US 6,700,542 B2
• Filed: 04/15/2002
• Issued: 03/02/2004
• Est. Priority Date: 10/19/2001
• Status: Active Grant

• Current Assignee: B. E. A. S. A.
• Original Assignee: Beasa
• Inventors: Borlez, Yves, Secretin, Laurent
• Primary Examiner(s): Nguyen, Hoang V.
• Assistant Examiner(s): Dinh, Trinh Vo
• Application Number:
  US10/122,553
• Publication Number:
  US 20030076271A1
• Time in Patent Office: 687 Days
• Field of Search: H01/Q.138, H04/M.100, 343/700.MS, 343/810, 343/853, 343/876, 342/79, 342/99, 342/134, 342/359, 345/76, 455/562, 333/135, 333/137, 333/208, 333/248
• US Class Current: 343/700.0MS
• CPC Class Codes: E05F 15/73 responsive to movement or presence of persons or objects
• CPC Class Codes: E05Y 2400/54 Obstruction or resistance detection
• CPC Class Codes: E05Y 2800/22 of not identical elements of the same category, e.g. combinations of not identical springs
• CPC Class Codes: E05Y 2900/132 Doors
• CPC Class Codes: G01S 13/56 for presence detection presence detection using near field arrangements G01V3/00, e.g. G01V3/08, G01V3/12; burglar, theft or intruder alarms with electrical actuation G08B13/22 - G08B13/26
• CPC Class Codes: G01S 7/024 using polarisation effects in waveguides H01P1/165; for aerials H01Q, e.g. H01Q15/22, H01Q15/24, H01Q19/195
• CPC Class Codes: H01Q 1/22 by structural association with other equipment or articles
• CPC Class Codes: H01Q 1/247 with frequency mixer, e.g. for direct satellite reception or Doppler radar
• CPC Class Codes: H01Q 21/065 Patch antenna array
• 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

The invention is a planar antenna which comprises a plurality of antenna elements positioned relative to each other in a predetermined orientation. Each of the elements is selectively electrically connectable to one or more of the other antenna elements. A plurality of switches electrically connect the plurality of antenna elements to each other. The switches are opened and closed by a signal operating at high speed enabling the antenna to act alternately in a first antenna configuration and a second antenna configuration using the same antenna structure. Doppler signals from the first and second antenna configurations are processed to determine the direction of a person or object in relation to a door.

Claims

1. A planar antenna (30) comprising:

a plurality of antenna elements (33, 41, 49) positioned relative to each other in a predetermined orientation, each of the plurality of antenna elements (33, 41, 49) being selectively electrically connectable to one or more of the other antenna elements,

a plurality of switches (56, 57) electrically connecting the plurality of antenna elements so that closing one of the switches causes at least two antenna elements to be electrically connected,

an antenna array (30) defined by the plurality of switches (56, 57) in combination with the plurality of antenna elements (33, 41, 49), characterized in that

a central antenna element and two lateral antenna elements (33, 41, 49) are positioned on a planar substrate (31) in such a way that at least two different lobes (70, 72) of the antenna are provided by activating different antenna elements (33, 41, 49) by said switches (56, 57) said antenna elements (33, 41, 49) comprise each at least two patches (34, 36, 38, 40, 42, 44, 46, 48, 50), wherein the patches of each antenna element are electrically connected by vertical lines (58, 60, 62) and the lateral antenna elements (33, 41) respectively and the central antenna element (49) are electrically connectable by said switches (56, 57).

2. A planar antenna according to claim 1 wherein said planar antenna is employed as a door opener sensor (152) which performs a parallel traffic rejection algorithm which processes the information received from said planar antenna in such a way that at least two different lobes (154, 156) of said planar antenna are analyzed in order to calculate the direction of a pedestrian moving in or near to the area covered by said Door opener Sensor (152).

3. A planar antenna according to claim 1, characterized in that,

a waveguide (10) is provided for coupling to the planar antenna.

4. A planar antenna according to claim 3, characterized in that

the waveguide (10) comprises a transition (18) to the planar antenna which is terminated by a waveguide flange (16).

5. A planar antenna according to claim 1, characterized in that

the plurality of antenna elements (33, 41, 49) comprise patches (34, 36, 38, 40, 42, 44, 46, 48, 50) on the planar substrate (31).

6. A planar antenna according to claim 5, characterized in that

the patches (34, 36, 38, 40, 40, 42, 46, 48, 50) comprise a central patch (50) which performs a coupling function to a microwave circuitry, such as a waveguide (10), a coaxial probe, via a hole, a slot coupling or any other type of coupling.

7. A planar antenna according to claim 5, characterized in that,

a waveguide (10) is provided for coupling to the planar antenna.

8. A planar antenna according to claim 7, characterized in that

the waveguide (10) comprises a transition (18) to the planar antenna which is terminated by a waveguide flange (16).

9. A planar antenna according to claim 6, characterized in that

all other patches (34, 36, 38, 40, 42, 44, 46, 48) have a length which is optimized to make the respective patch resonate at a central frequency and a width which is adjusted to the impedance and radiation power of the antenna.

10. A planar antenna according to claim 9, characterized in that

it comprises a left, a central and a right antenna element (33, 41, 49) each comprising three patches (34, 36, 38, 40, 42, 44, 46, 48, 50), wherein the patches of each antenna element are electrically connected by vertical lines (58, 50, 62) and the left and right antenna elements (33, 41) respectively and the central antenna element (49) are electrically connectable by switches (56, 57).

11. A planar antenna according to claim 10, characterized in that,

a waveguide (10) is provided for coupling to the planar antenna.

12. A planar antenna according to claim 11, characterized in that

the waveguide (10) comprises a transition (18) to the planar antenna which is terminated by a waveguide flange (16).

13. A planar antenna according to claim 9, characterized in that,

a waveguide (10) is provided for coupling to the planar antenna.

14. A planar antenna according to claim 13, characterized in that

the waveguide (10) comprises a transition (18) to the planar antenna which is terminated by a waveguide flange (16).

15. A planar antenna according to claim 6, characterized in that

it comprises a left, a central and a right antenna element (33, 41, 49) each comprising three patches (34, 36, 38, 40, 42, 44, 46, 48, 50), wherein the patches of each antenna element are electrically connected by vertical lines (58, 50, 62) and the left and right antenna elements (33, 41) respectively and the central antenna element (49) are electrically connectable by switches (56, 57).

16. A planar antenna according to claim 15, characterized in that,

a waveguide (10) is provided for coupling to the planar antenna.

17. A planar antenna according to claim 16, characterized in that

the waveguide (10) comprises a transition (18) to the planar antenna which is terminated by a waveguide flange (16).

18. A planar antenna according to claim 6, characterized in that,

a waveguide (10) is provided for coupling to the planar antenna.

19. A planar antenna according to claim 18, characterized in that

the waveguide (10) comprises a transition (18) to the planar antenna which is terminated by a waveguide flange (16).

20. A planar antenna according to claim 1, characterized in that,

a waveguide (10) is provided for coupling to the planar antenna.

21. A planar antenna according to claim 20, characterized in that

the waveguide (10) comprises a transition (18) to the planar antenna which is terminated by a waveguide flange (16).

22. A planar antenna according to claim 21, characterized in that

the transition (18) comprises a “

Doggy bone”

filter (20) which reduces the spurious radiation at harmonic frequencies.

23. A planar antenna according to claim 22, characterized in that

the distance between the “

Doggy bone”

filter (20) and the plane of the planar antenna (3) is about a waveguide length when the waveguide (10) is mounted on the surface of the planar antenna (30).

24. A planar antenna according to claim 20, characterized in that

the waveguide (10) is enlarged in its larger dimension in order to ensure a constant electromagnetic field on its rear aperture to provide impedance matching.

25. A planar antenna according to claim 24 wherein said waveguide (10) comprises a rectangular aperture which is designed to provide enough energy to said central patch (5) and to ensure a good matching between the waveguide (10) and said planar antenna.

26. A planar antenna according to claim 25 wherein said switches are PIN diodes.

27. A planar antenna according to claim 26 further comprising a path for DC current to polarize said PIN diodes and formed to have no influence on the antenna radiation pattern.

28. A planar antenna according to claim 27 further comprising connection pads (52, 54) for applying DC current to said diodes.

29. A planar antenna according to claim 28 further comprising control lines (66, 68) and a material absorbing microwaves covering said control lines (66, 68).

30. A planar antenna according to claim 1 further comprising circuitry for controlling said planar antenna (30) by obtaining at least one Doppler Signal from at least one measurement device (100, 102) working with at least one lobe of said planar antenna (30), and, processing said Doppler Signal according to an algorithm and performing high-speed switching between the configurations of said planar antenna (30) in accordance with said algorithm.

31. A planar antenna according to claim 30 wherein said circuitry further comprises sample and hold circuits (114, 116, 118, 120) for sampling said obtained Doppler Signals.

32. A planar antenna according to claim 31 wherein said sample and hold circuits (114, 116, 118, 120) are synchronized with said high-speed switching.

33. A planar antenna according to claim 32 wherein said circuitry comprises a digital signal processor for processing said Doppler Signal.

34. A planar antenna according to claim 33 wherein said digital signal processor processes two Dopplor Signals obtained from two measurement devices (100, 102) and corresponding to two different lobes of said planar antenna and calculates from said Doppler Signals an intermediate lobe by weighting said Doppler Signals.

35. A planar antenna according to claim 34 further comprising an oscillator (108) which produces a sampling frequency signal with an accuracy suitable for sampling.

36. A planar antenna according to claim 35 wherein said sampling is performed by pulse width modulation.

37. A planar antenna as claimed in claim 2 wherein said planar antenna is mounted on a door header and operates as a door opener sensor and controller.

38. A planar antenna as claimed in claim 1 wherein said switches (56, 57) are located on the antenna substrate.

39. A planar antenna (30) comprising:

a plurality of antenna elements (33, 41,49) positioned relative to each other in a predetermined orientation, each of the plurality of antenna elements (33, 41, 49) being selectively electrically connectable to one or more of the other antenna elements, a plurality of switches (56, 57) electrically connecting the plurality of antenna elements so that closing one of the switches causes at least two antenna elements to be electrically connected, an antenna array (30) defined by the plurality of switches (56, 57) in combination with the plurality of antenna elements (33, 41,49), characterized in that

the antenna elements (33, 41, 49) are positioned on a planar substrate (31) in such a way that at least two different lobes (154, 156) of the antenna are provided by activating different antenna elements (33, 41,49) by said switches (56, 57) located on the antenna substrate, circuitry for controlling said planar antenna (30) which obtains Doppler Signals from measurement devices, said circuitry comprises a digital signal processor for processing said Doppler Signals, and, said digital signal processor performs a parallel traffic rejection algorithm which processes said Doppler Signals such that said at least two different lobes (154, 156) of said planar antenna are analyzed to calculate the direction of a pedestrian moving in or near to the area covered by said planar antenna.

40. A planar antenna (30) comprising:

a plurality of antenna elements (33, 41, 49) positioned relative to each other in a predetermined orientation, each of said plurality of antenna elements (33, 41, 49) being selectively electrically connectable to said other antenna elements, a plurality of switches (56, 57) electrically connecting said plurality of antenna elements so that closing said switches causes said antenna elements (33, 41, 49) to be electrically connected in a first antenna configuration and that opening said switches isolates antenna element (49) in a second antenna configuration, each said antenna element comprises three patches and said antenna element (49) includes a central radiation patch for distribution of power to said antenna elements (33, 41).