METHODS AND APPARATUS FOR A DUAL POLARIZATION ANTENNA SYSTEM

• US 20100315195A1
• Filed: 06/12/2009
• Published: 12/16/2010
• Est. Priority Date: 06/12/2009
• Status: Abandoned Application

• Current Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Duron, Mark, Knadle, Richard
• Application Number:
  US12/483,508
• Publication Number:
  US 20100315195A1
• Time in Patent Office: Days
• US Class Current: 340/5.1
• CPC Class Codes: H01Q 1/2216 used in interrogator/reader equipment
• CPC Class Codes: H01Q 21/24 Combinations of antenna units polarised in different directions for transmitting or receiving circularly and elliptically polarised waves or waves linearly polarised in any direction circularly polarised patch antennas H01Q9/0428; circularly polarised horns H01Q13/0241; cross-polarised horns H01Q13/0258; polarisation converters H01Q15/242; cross-polarised rear feeds H01Q19/136; crossed polarisation dual antenna H01Q25/001
• CPC Class Codes: H01Q 21/28 Combinations of substantially independent non-interacting antenna units or systems multiple beam H01Q25/00

Abstract

A dual polarization antenna system includes a dipole antenna oriented along a first plane (e.g., a horizontal plane), and a monopole antenna oriented along a second plane (e.g., a vertical plane) orthogonal to the first plane, wherein the monopole antenna is referenced to a V-null point of the dipole antenna.

Claims

3-1. The antenna system of claim 3, wherein the dipole antenna comprises two dipole halves extending from the V-null point, and each have an electrical length equal to ¼

of the wavelength of the RF signal.

8. An antenna system for a mobile RFID reader, comprising:

a horizontal antenna structure comprising a first half dipole and a second half dipole extending from a v-null point, wherein the horizontal antenna structure is a first monostatic RFID reader antenna;

a vertical antenna structure comprising a monopole extending from the v-null point, wherein the vertical antenna structure is a second monostatic RFID reader antenna;

a first balun structure coupled to the vertical antenna structure;

a second balun component coupled to the horizontal antenna structure;

a first drive port coupled to the first balun component;

a second drive port coupled to the second balun component;

a multiplexer configured to alternately coupled an RF signal node to the first and second drive ports.

9. The antenna system of claim 8, wherein the first and second half dipole each have an electrical length equal to ¼

wavelength.

10. The antenna system of claim 8, further including an inductive shunt coupled to the first and second half dipoles from the V-null point.

11. The antenna system of claim 8, further including a first matching circuit coupled to the first balun component, and a second matching circuit coupled to the second balun component.

12. A method of communicating with RFID tags, comprising:

providing a dipole antenna oriented along a first plane;

providing a monopole antenna oriented along a second plane orthogonal to the first plane such that the monopole antenna is referenced to a V-null point substantially at the center of the dipole antenna; and

operating the dipole antenna and the monopole antenna as monostatic RFID reader antennas to communicate with the RFID tags.

13. The method of claim 12, including orienting the first plane as a horizontal plane, and orienting the second plane as a vertical plane.

14. The method of claim 12, including operating the dipole antenna and the monopole antenna within the frequency range of about 900 to 930 MHz.