RADIO FREQUENCY CONNECTION ARRANGEMENT

• US 20160240908A1
• Filed: 08/28/2015
• Published: 08/18/2016
• Est. Priority Date: 02/13/2015
• Status: Active Grant

• Current Assignee: Cambium Networks Limited (Cambium Networks Corporation)
• Original Assignee: Cambium Networks Limited (Cambium Networks Corporation)
• Inventors: King, Nigel Jonathan Richard, Strong, Peter, Wilkins, Adam, Morrell, Carl, Clark, Paul
• Granted Patent: US 9,837,697 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01P 3/081 Microstriplines
• CPC Class Codes: H01P 5/028 between strip lines
• CPC Class Codes: H05K 1/0225 Single or multiple openings in a shielding, ground or power plane H05K1/0227 takes precedence
• CPC Class Codes: H05K 1/0239 Signal transmission by AC coupling
• CPC Class Codes: H05K 1/025 Impedance arrangements, e.g. impedance matching, reduction of parasitic impedance H05K1/024 and H05K1/0243 take precedence; for semiconductor devices H01L23/66

Abstract

A radio frequency transmission arrangement comprises a ground plate having an aperture comprising a slot with an elongate cross-section and substantially parallel sides, and a first and second transmission line. The thickness of the ground plate is greater than a width of the slot. The first transmission line comprises a first elongate conductor on a first side of the ground plate and has an end terminated with a first termination stub. The second transmission line comprises a second elongate conductor on the opposite side of the ground plate and has an end terminated with a second termination stub. The first transmission line is arranged to cross the slot at a point adjacent to the first termination stub, and the second transmission line is arranged to cross the slot at a point adjacent to the second termination stub.

Claims

1. A radio frequency transmission arrangement comprising:

a ground plate having first and second opposite sides and an aperture passing through the ground plate from the first side to the second side, the aperture comprising a slot, the slot having an elongate cross-section in the plane of the first side of the ground plate, the cross-section having substantially parallel sides extending along the length of the cross section, and the slot having a width which is the distance between the parallel sides of the cross-section of the slot;

a first transmission line comprising a first elongate conductor disposed on the first side of the ground plate in a substantially parallel relationship with the first side of the ground plate, the first transmission line having an end terminated with a first termination stub; and

a second transmission line comprising a second elongate conductor disposed on the second side of the ground plate in a substantially parallel relationship with the second side of the ground plate, the second transmission line having an end terminated with a second termination stub,

wherein the first transmission line is arranged to cross the slot at a point adjacent to the first termination stub, and the second transmission line is arranged to cross the slot at a point adjacent to the second termination stub, and

wherein a thickness of the ground plate is greater than a width of the slot.

2. The radio frequency transmission arrangement of claim 1, wherein the aperture is an air-filled cavity.

3. The radio frequency transmission arrangement of claim 1, wherein the ground plate is composed of a non-conductive moulding having an electrically conductive coating.

4. The radio frequency transmission arrangement of claim 3, wherein the non-conductive moulding comprises a plastic material and the conductive surface comprises copper.

5. The radio frequency transmission arrangement of claim 1, wherein the ground plate is composed of metal.

6. The radio frequency transmission arrangement of claim 5, wherein the ground plate is composed of cast aluminium.

7. The radio frequency transmission arrangement of claim 1, wherein the thickness of the ground plate is greater than four times the width of the slot.

8. The radio frequency transmission arrangement of claim 1, wherein the width of the slot is greater than 1 mm and the thickness of the ground plate is greater than 5 mm.

9. The radio frequency transmission arrangement of claim 1, wherein the width of the slot is in the range 1 to 3 mm and the thickness of the ground plate is in the range 5 to 15 mm.

10. The radio frequency transmission arrangement of claim 1, wherein the aperture comprises a termination cavity at each end of the slot.

11. The radio frequency transmission arrangement of claim 10, wherein each termination cavity is cylindrical.

12. The radio frequency transmission arrangement of claim 1, wherein the slot has a length of less than a wavelength at an operating frequency of the radio frequency transmission arrangement.

13. The radio frequency transmission arrangement of claim 12, wherein the slot has a length of less than 0.3 of a wavelength at an operating frequency of the radio frequency transmission arrangement.

14. The radio frequency transmission arrangement of claim 1, wherein the first transmission line crosses the slot directly opposite the point where the second transmission line crosses the slot.

15. The radio frequency transmission arrangement of claim 1, wherein the first transmission line crosses the slot at a point offset along the slot from the point where the second transmission line crosses the slot.

16. The radio frequency transmission arrangement of claim 1, wherein the first transmission line is formed by a printed track on a polyester film, disposed with an air gap between the polyester film and the ground plate.

17. The radio frequency transmission arrangement of claim 1, wherein the first and second terminating stubs have a diameter of substantially 0.1 of a wavelength at an operating frequency of the radio frequency transmission structure.

18. The radio frequency transmission arrangement of claim 11, wherein each cylindrical terminating cavity has a diameter of substantially 0.1 of a wavelength at an operating frequency of the radio frequency transmission structure.

19. The radio frequency transmission arrangement of claim 1, wherein the ground plate has a protrusion from the second side, the protrusion being arranged to pass through an opening in a metal plate disposed in a substantially parallel relationship with the ground plate, and the aperture being arranged to pass through the protrusion, whereby to provide a radio frequency connection through the metal plate to the second transmission line.