Electronically steerable sector antenna

• US 7,397,425 B2
• Filed: 12/30/2004
• Issued: 07/08/2008
• Est. Priority Date: 12/30/2004
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Yin, Qin-Ye, Jiang, Yan-Sheng, King, Wayne, Ranta, Craig Steven
• Primary Examiner(s): Tarcza; Thomas H.
• Assistant Examiner(s): Mull; Fred H.
• Application Number:
  US11/027,748
• Publication Number:
  US 20060145921A1
• Time in Patent Office: 1,286 Days
• Field of Search: 342368-377, 455/562.1
• US Class Current: 342/374
• CPC Class Codes: H01Q 1/007 specially adapted for indoor communication
• CPC Class Codes: H01Q 1/2258 used with computer equipment
• 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 3/24 varying the orientation by switching energy from one active radiating element to another, e.g. for beam switching
• CPC Class Codes: H01Q 3/2682 Time delay steered arrays
• CPC Class Codes: H01Q 3/36 with variable phase-shifters

Abstract

An electronically steerable antenna system includes a plurality of panels that are coupled together to form an N-sided polygon. Each panel includes a plurality of microstrip conductor patches forming a phased array antenna. In a first embodiment that includes beam steering, each panel can selectively transmit or receive in a direction that is either perpendicular to the panel, or to the left or right of perpendicular, depending upon relative delay line lengths applied to the left and right antennas. A second embodiment omits the beam steering capability for each panel and simply enables only one of the N different panels to be employed for transmitting or receiving a radiofrequency signal in a direction perpendicular to the panel. PIN diodes are preferably used for selecting the panel that is active, and in the first embodiment, for selecting the delay lines used.

Claims

1. A steerable antenna that is selectively controllable in regard to a direction in which the antenna is usable for transmitting or receiving a radio frequency (RF) signal, comprising:

(a) a plurality of panels that are coupled together along edges of the panels, each panel being substantially flat and oriented so that an outwardly facing surface of the panel faces in a substantially different direction from outwardly facing surfaces of other of the plurality of panels, each panel including a plurality of discrete microstrip antennas that comprise a phased array antenna including a left panel antenna, a center panel antenna, and a right panel antenna for transmitting an RF signal in a direction outwardly from the face of the panel;

(b) an omni-directional antenna configured to receive an indication from a destination device that the signal is greatest when the signal is transmitted to a determined position;

(c) a panel selector switch circuit that is controllable in response to a selector signal to selectively activate one of the plurality of panels for transmitting an RF signal, the panel selector switch circuit being coupled to an antenna terminal on each panel;

(d) a signal splitter configured to split the RF signal into separate first, second, and third instances of the RF signal; and

(e) a delay selector switch circuit configured to electronically steer the focus of the phased array antenna in the direction of the strongest detected signal strength according to the indication received by the omni-directional antenna, the first instance of the RF signal being routed through a longer delay that is longer than a reference delay, the second instance of the RF signal being routed through the reference delay, the third instance of the RF signal being routed through a shorter delay that is shorter than the reference delay, each of the first, second, and third instances of the RF signal being routed simultaneously through the corresponding longer, reference, and shorter delays, respectively, such that, as a result of the different delays, each of the first, second and third instances of the RF signal is transmitted at a different time from a different panel antenna, but each of the first, second, and third instances of the RF signal arrive at the destination device at substantially the same time, thereby strengthening the transmitted signal.

2. The steerable antenna of claim 1, wherein the plurality of panels are oriented substantially vertically and form an N-sided polygon, where N is equal to the number of panels in the plurality of panels.

3. The steerable antenna of claim 1, wherein the panel selector switch circuit includes a plurality of positive-intrinsic-negative (PIN) diode switches.

4. The steerable antenna of claim 1, further comprising:

(a) a plurality of delay circuits, each of which is selectively coupled to a different one of the plurality of discrete microstrip antennas; and

(b) a delay switch circuit that is selectively controllable to determine which of the plurality of selective delay circuits that provide a desired delay is selected, thereby controlling a direction in which an RF signal is transmitted by the phased array antenna on the panel.

5. The steerable antenna of claim 1, wherein each panel comprises a printed circuit board on which the discrete microstrip antennas that comprise a phased array antenna are formed as conductive traces.

6. The steerable antenna of claim 1, wherein the plurality of panels and each of the plurality of discrete microstrip antennas are sized for transmitting and receiving signals at radio frequencies used for communicating data over a wireless computing network.

7. The steerable antenna of claim 1, wherein the panel selector switch circuit is controlled in response to a logic level panel selector signal as a function of a desired direction for transmitting an RF signal.

8. The steerable antenna of claim 1, wherein the delay selector switch circuit is controlled in response to a logic level directional selector signal as a function of a desired direction for transmitting an RF signal.

9. The steerable antenna of claim 1, further comprising:

receiving a second indication at the omni-directional antenna from the destination device that the signal strength is greater when the signal is transmitted to a second, different position, the position being determined by the omni-directional antenna; and

automatically steering the focus of the phased array antenna to the determined second position based on the received second indication.

10. The steerable antenna of claim 1, wherein each of the plurality of panels comprises a printed circuit board.

11. A method for controlling a direction in which a steerable antenna is used for transmitting a radio frequency (RF) signal, comprising the steps of:

(a) receiving an indication from a destination device that a transmission signal transmitted by the steerable antenna is greatest when the signal is transmitted to a determined position;

(b) selectively activating one of a plurality of substantially planar antenna panels that comprise the steerable antenna, wherein the planar antenna panels face in substantially different directions, each panel including a plurality of discrete microstrip antennas that comprise a phased array antenna including a left panel antenna, a center panel antenna, and a right panel antenna and which are used for one of radiating an RF signal generally outwardly from the outer surface and receiving an RF signal that is directed toward the outer surface of the panel, so that a specific panel of the plurality of panels that faces generally in the preferred direction is selectively activated to transmit the RF signal;

(c) splitting the RF signal into separate first, second and third instances of the RF signal; and

(d) steering the focus of the phased array antenna using a delay selector switch in the direction of the strongest detected signal strength according to the indication received by the omni-directional antenna, the first instance of the RF signal being routed through longer delay that is longer than a reference delay, the second instance of the RF signal being routed through the reference delay, the third instance of the RF signal being routed through a shorter delay that is shorter than the reference delay, each of the first, second, and third instances of the RF signal being routed simultaneously through the corresponding longer, reference, and shorter delays, respectively, such that, as a result of the different delays, each of the first, second and third instances of the RF signal is transmitted at a different time from a different panel antenna, but each of the first, second, and third instances of the RF signal arrive at the destination device at substantially the same time, thereby strengthening the transmitted signal.

12. The method of claim 11, further comprising the step of selectively steering the radio signal that is transmitted, for the panel that was activated, so that a direction in which the radio signal is transmitted more closely matches the preferred direction.

13. The method of claim 12, wherein the step of determining the preferred direction for transmitting the RF signal comprises the step of selecting the direction to ensure that substantially a best signal strength for the RF signal that is received, to enable the direction to be controlled in a high multi-path environment where the RF signal that is received may have been reflected from one or more surfaces.

14. The method of claim 11, wherein the step of selectively activating comprises the step of responding to a panel select signal indicating the panel that should be activated to transmit the RF signal in the preferred direction.

15. The method of claim 11, further comprising step of automatically repetitively determining the preferred direction and selecting the panel to use for transmitting the RF signal, in response to propagation path changes that affect a signal strength of the RF signal.

16. A steerable antenna that is selectively controllable in regard to a direction in which the antenna is usable for receiving a radio frequency (RF) signal, comprising:

(a) a plurality of panels that are coupled together along edges of the panels, each panel being substantially flat and oriented so that an outwardly facing surface of the panel faces in a substantially different direction from outwardly facing surfaces of other of the plurality of panels, each panel including a plurality of discrete microstrip antennas that comprise a phased array antenna including a left panel antenna, a center panel antenna, and a right panel antenna for receiving an RF signal in a direction outwardly from the face of the panel;

(b) an omni-directional antenna configured to receive an indication from a destination device that the signal is greatest when the signal is received from a determined position;

(c) a panel selector switch circuit that is controllable in response to a selector signal to selectively activate one of the plurality of panels for receiving an RF signal, the panel selector switch circuit being coupled to an antenna terminal on each panel;

(d) a signal splitter configured to split the RF signal into separate first, second, and third instances of the RF signal; and

(e) a delay selector switch circuit configured to electronically steer the focus of the phased array antenna in the direction of the strongest detected signal strength according to the indication received by the omni-directional antenna, the first instance of the RF signal being routed through a longer delay that is longer than a reference delay, the second instance of the RF signal being routed through the reference delay, the third instance of the RF signal being routed through a shorter delay that is shorter than the reference delay, each of the first, second, and third instances of the RF signal being routed simultaneously through the corresponding longer, reference, and shorter delays, respectively, such that, as a result of the different delays, each of the first, second and third instances of the RF signal is received at a different time from a different panel antenna, but each of the first, second, and third instances of the RF signal arrive at a signal processor of the steerable antenna at substantially the same time, thereby strengthening the received signal.

17. The steerable antenna of claim 16, wherein the plurality of panels are oriented substantially vertically and form an N-sided polygon, where N is equal to the number of panels in the plurality of panels.

18. The steerable antenna of claim 16, wherein the panel selector switch circuit includes a plurality of positive-intrinsic-negative (PIN) diode switches.

19. The steerable antenna of claim 16, further comprising:

(a) a plurality of delay circuits, each of which is selectively coupled to a different one of the plurality of discrete microstrip antennas; and

(b) a delay switch circuit that is selectively controllable to determine which of the plurality of selective delay circuits that provide a desired delay is selected, thereby controlling a direction in which an RF signal is received by the phased array antenna on the panel.

20. The steerable antenna of claim 16, wherein each panel comprises a printed circuit board on which the discrete microstrip antennas that comprise a phased array antenna are formed as conductive traces.

21. The steerable antenna of claim 16, wherein the plurality of panels and each of the plurality of discrete microstrip antennas are sized for transmitting and receiving signals at radio frequencies used for communicating data over a wireless computing network.