Multibeam antenna having auxiliary antenna elements

• US 6,252,560 B1
• Filed: 02/22/2000
• Issued: 06/26/2001
• Est. Priority Date: 02/22/1999
• Status: Expired due to Fees

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Saito, Toshiya, Tanaka, Makoto
• Primary Examiner(s): PHAN, THO GIA
• Application Number:
  US09/510,113
• Time in Patent Office: 490 Days
• Field of Search: 343/713, 343/754, 343/778, 343/844, 343/850, 343/853, 343/852, 343/860, 342/371, 342/372, 342/373, 342/375, 342/378, 342/379, 455/428, 455/429
• US Class Current: 343/853
• CPC Class Codes: H01Q 21/08 the units being spaced along or adjacent to a rectilinear path waveguide fed H01Q21/0037
• CPC Class Codes: H01Q 21/22 Antenna units of the array energised non-uniformly in amplitude or phase, e.g. tapered array or binomial array
• CPC Class Codes: H01Q 25/00 Antennas or antenna systems providing at least two radiating patterns arrangements for changing or varying the orientation or the shape of the directional pattern H01Q3/00
• CPC Class Codes: H01Q 3/40 with phasing matrix

Abstract

A multibeam antenna for forming multiple beams includes an antenna array and a Butler-matrix feeder circuit. The antenna array is composed of 2ⁿ main antenna elements and a group of 2ⁿ or less auxiliary antenna elements placed at either one or both sides of the main antenna elements. Antenna power is supplied to the antenna array from the Butler-matrix feeder circuit and is distributed to all the antenna elements with higher power to the elements located in the middle of the array and lower power to the elements located at sides of the array. Phase of the power supplied to the main antenna elements is shifted by 180-degree, and the phase-shifted power is distributed to predetermined auxiliary antenna elements. Thus, sidelobes associated with antenna beams are reduced and the beam directivity is improved.

Claims

1. A multibeam antenna comprising:

a Butler-matrix feeder circuit;

transmission lines built in the Butler-matrix feeder circuit;

2ⁿ main antenna elements to which power is supplied from the Butler-matrix feeder circuit through the transmission lines; and

2ⁿ or less auxiliary antenna elements constituting an auxiliary antenna group, the auxiliary antenna group being located at either one or both sides of the main antenna elements, thereby forming an antenna element array together with the main antenna elements, the power being distributed from the Butler-matrix feeder circuit to the auxiliary antenna elements through the transmission lines.

2. The multibeam antenna as in claim 1, wherein:

a phase difference between two neighboring antenna elements is made equal throughout the antenna element array.

3. The multibeam antenna as in claim 2, wherein:

a second power, a phase of which is 180-degree-shifted from a phase of a first power supplied to one of the main antenna elements, is distributed to one of the auxiliary antenna elements which is located apart from the one of the main antenna elements by 2ⁿ antenna elements in the antenna element array.

4. The multibeam antenna as in claim 2 or 3, wherein:

stubs for making the phase difference between two neighboring antenna elements equal are disposed in the transmission lines.

5. The multibeam antenna as in claim 1, 2 or 3, wherein:

all of the main and auxiliary antenna elements are located with equal intervals therebetween in the antenna element array.

6. The multibeam antenna as in claim 1, 2 or 3, wherein:

the power from the Butler-matrix feeder circuit is distributed to all of the main and auxiliary antenna elements, so that less power is supplied to the antenna elements remoter from a center of the antenna element array.

7. The multibeam antenna as in claim 1, 2 or 3, wherein:

all of the main and auxiliary antenna elements are circularly polarized antenna elements.

8. The multibeam antenna as in claim 1, 2 or 3, wherein:

the power to be fed to the auxiliary antenna elements is directly distributed from an input port of the Butler-matrix feeder circuit through power dividers.

9. A multibeam antenna comprising:

a Butler-matrix feeder circuit;

transmission lines built in the Butler-matrix feeder circuit;

four main antenna elements to which power is supplied from the Butler-matrix feeder circuit through the transmission lines; and

an auxiliary antenna element located at one side of the main antenna elements, and another auxiliary antenna element located at the other side of the main antenna elements, thereby forming an antenna element array including the main and auxiliary antenna elements, so that all the antenna elements can be identified with sequential numbers from No. 1 to No. 6 ascending from one side of the array toward the other side of the array;

a power divider for distributing power supplied to No. 5 main antenna element to No. 1 auxiliary antenna element, a phase of the power distributed to No. 1 auxiliary antenna element being 180-degree shifted from a phase of the power supplied to No. 5 main antenna element; and

another power divider for distributing power supplied to No. 2 main antenna element to No. 6 auxiliary antenna element, a phase of the power distributed to No. 6 auxiliary antenna element being 180-degree shifted from a phase of the power supplied to No. 2 main antenna, wherein;

a phase difference between two neighboring antenna elements is made equal throughout the antenna element array; and

the transmission line connected to No. 2 main antenna element crosses the transmission line connected to No. 3 main antenna element, and the transmission lined connected to No. 5 main antenna element crosses the transmission line connected to No. 4 main antenna element.

10. A multibeam antenna comprising:

2ⁿ main antenna elements; and

2ⁿ or less auxiliary antenna elements constituting an auxiliary antenna group, the auxiliary antenna group being located at either one or both sides of the main antenna elements, thereby forming an antenna element array together with the main antenna elements, wherein;

a second electric power, a phase of which is 180-degree shifted from a phase of a first electric power supplied to one of the main antenna elements, is distributed to one of the auxiliary antenna elements which is located apart from the one of the main antenna elements by 2ⁿ antenna elements in the antenna element array;

a phase difference between two neighboring antenna elements is made equal throughout the antenna element array; and

frequency conversion and analog-digital conversion are performed for the main antenna elements, and then fast Fourier transform is performed, so that multiple beams are formed by the antenna element array.

11. A multibeam antenna comprising:

a Butler-matrix feeder circuit;

transmission lines built in the Butler-matrix feeder circuit;

2ⁿ main antenna elements to which power is supplied from the Butler-matrix feeder circuit through the transmission lines; and

2ⁿ or less auxiliary antenna elements constituting an auxiliary antenna group, the auxiliary antenna group being located at either one or both sides of the main antenna elements, thereby forming an antenna element array together with the main antenna elements, power being distributed from the Butler-matrix feeder circuit to the auxiliary antenna elements through the transmission lines, wherein;

a phase difference between two neighboring antenna elements is made equal throughout the antenna element array; and

a second power, a phase of which is 180-degree-shifted from a phase of a first power supplied to one of the main antenna elements, is distributed to one of the auxiliary antenna elements which is located apart from the one of the main antenna elements by 2ⁿ antenna elements in the antenna element array.

12. An antenna system comprising:

three multibeam antennas defined in claim 11; and

a triangular or round pillar for mounting the three multibeam antennas thereon, wherein;

the three multibeam antennas are mounted on the pillar so that multiple beams formed by the antennas are uniformly directed to all directions to cover 360-degree communication around the antenna system.

13. An antenna system comprising:

the multibeam antenna defined in claim 11 located over a road so that multiple beams formed by the multibeam antenna are directed toward the road to perform wireless communication with vehicles driving on the road.

14. An antenna system comprising:

the multibeam antenna defined in claim 11 mounted on a vehicle driving on a road, so that multiple beams formed by the multibeam antenna are directed upward; and

an antenna of a communication terminal located over the road to perform wireless communication between the communication terminal and the vehicle.

15. An antenna system comprising:

a multibeam antenna defined in claim 11 carried by a vehicle driving on a road, so that multiple beams formed by the multibeam antenna are directed upward; and

another multibeam antenna defined in claim 11 located over the road to transmit multiple beams formed by the multibeam antenna toward the vehicle for performing wireless communication with the vehicle.

16. An antenna system comprising:

a multibeam antenna defined in claim 11;

a switching circuit for selecting one or more beams from multiple beams formed by the multibeam antenna;

an amplifier circuit for amplifying the selected beams;

a phase shifter for controlling phases of the amplified beams; and

a power combiner for combining outputs from the phase shifter into one output.