ANTENNA SWITCHING ARRANGEMENT

• US 20110032079A1
• Filed: 08/10/2009
• Published: 02/10/2011
• Est. Priority Date: 08/10/2009
• Status: Active Grant

• Current Assignee: RF Controls LLC
• Original Assignee: RF Controls LLC
• Inventors: Pierce, Matthew E., Turner, Christopher Gordon Gervase, Bloy, Graham P.
• Granted Patent: US 8,344,823 B2
• Time in Patent Office: Days
• US Class Current: 340/10.1
• CPC Class Codes: G06K 7/01 Details
• CPC Class Codes: H01P 5/02 with invariable factor of coupling H01P5/12 takes precedence choke joints H01P1/04, H01P1/06
• 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 21/245 provided with means for varying the polarisation polarising devices H01Q15/24; tracking by comparing linear polarisation compounds G01S3/146; reducing depolarisation effects H04B7/00; polarisation diversity H04B7/10
• 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

An antenna switching arrangement with a quadrature arrangement of transmission lines through which a desired signal path may be configured via switches selectively grounding junctions of the switching arrangement. The desired path routing a signal from an input port to one or both of first and second output ports to generate a signal with vertical linear polarization, horizontal linear polarization or circular polarization. The selected polarization may be changed as desired and/or multiple antenna switching arrangements applied to enable simultaneous signals with different polarizations.

Claims

1. An antenna switching arrangement, comprising:

an input port coupled via a fourth transmission line to a fourth junction of a quadrature arrangement of quadrature transmission lines also provided with a first, a second and a third junction;

the first junction provided with a first switch operable to selectively couple the first junction to ground;

the second junction provided with a second switch operable to selectively couple the second junction to ground;

the third junction provided with a third switch operable to selectively couple the third junction to ground;

the first junction coupled via a first transmission line to a first output port;

the second junction coupled via a second transmission line to a second output port;

a terminating junction coupled via a third transmission line to the third junction;

a fourth switch operable to selectively couple the terminating junction to ground; and

a resistor coupled between the terminating junction and ground.

3. The arrangement of claim 1, wherein the first, second, third and fourth quadrature transmission lines, each have an electrical length of one quarter of a wavelength of a desired signal frequency.

4. The arrangement of claim 1, wherein the switches are diodes.

5. The arrangement of claim 1, wherein the switches are each inductors;

the switches selectable by applying a control voltage to the inductor selected to cause magnetic saturation of a core of the inductor, reducing a reactance of the inductor.

6. The arrangement of claim 1, wherein the first output is coupled to a vertical linear polarization antenna.

7. The arrangement of claim 1, wherein the second output is coupled to a horizontal linear polarization antenna.

8. The arrangement of claim 1, wherein the quadrature transmission lines are traces on a printed circuit board.

9. The arrangement of claim 1, further including multiple antenna switching arrangements, the first switch, second switch, third switch and fourth switch of each of the multiple antenna switching arrangements controlled by a controller.

10. The arrangement of claim 1, wherein the quadrature transmission lines are formed using at least one lumped reactive component.

11. The arrangement of claim 10, wherein the switches are each inductors integral to the transmission line inductors;

the switches selectable by applying a control voltage to the inductor selected to cause magnetic saturation of a core of the inductor, reducing a reactance of the inductor.

12. A method for switching the polarity of an RF signal, comprising the steps of:

coupling the RF signal to an input port of a quadrature transmission line arrangement having a first output and a second output;

setting a plurality of switches of the quadrature transmission line arrangement to select a desired signal path between the first output, the second output and simultaneously to the first output and the second output.

13. The method of claim 12, wherein each of the plurality of switches selectively couples a respective junction of the quadrature transmission line arrangement to ground, thereby short circuiting the selected junction(s) to define the desired signal path.

14. The method of claim 12, wherein at least one of the switches is a diode.

15. The method of claim 12, wherein at least one of the switches is an inductor, the inductor isolated from the respective junction by a capacitor, the switches selectable by applying a control voltage to the inductor selected to cause magnetic saturation of a core of the inductor, reducing a reactance of the inductor.

16. The method of claim 12, wherein a phase of the signal at the first output and a phase of the signal at the second output are ninety degrees apart.

17. The method of claim 12, wherein the setting of the switches is alternated between defining the signal path resulting in a selected polarization of one of a vertical linear polarization, a horizontal linear polarization and a circular polarization.

18. The method of claim 12, wherein the setting of the switches is performed by a controller.

19. The method of claim 18, wherein the controller controls multiple separate quadrature transmission arrangements.

2. The arrangement of claim 1, wherein the first quadrature transmission line and the fourth quadrature transmission line have a characteristic impedance of generally 0.707 times a characteristic impedance of the input port.

20. The method of claim 19, wherein the controller directs at least one of the multiple separate quadrature transmission arrangements to generate a signal in a different polarization.

19-1. A method for reading an RFID tag, comprising the steps of:

broadcasting a signal with a first polarity;

recording a first response signal;

broadcasting a signal with a second polarity;

recording a second response signal;

comparing the first response signal with the second response signal.

20-2. The method of claim 19, wherein the broadcasting of the signal with the first polarity and the signal with the second polarity is simultaneous.