Aperture antenna having a high-impedance backing

• US 20030011522A1
• Filed: 06/12/2002
• Published: 01/16/2003
• Est. Priority Date: 06/15/2001
• Status: Active Grant

• Current Assignee: Wemtec Inc.
• Original Assignee: E-Tenna Corporation
• Inventors: McKinzie, William E. III, Aberle, James T.
• Granted Patent: US 6,906,674 B2
• Time in Patent Office: Days
• US Class Current: 343/700MS
• CPC Class Codes: H01Q 1/52 Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure absorbing means H01Q17/00
• CPC Class Codes: H01Q 13/10 Resonant slot antennas
• CPC Class Codes: H01Q 15/008 said selective devices having Sievenpipers' mushroom elements

Abstract

An antenna comprises a conductive member having an opening for radiating an electromagnetic signal. A circuit board is spaced apart from the conductive member by less than one-quarter wavelength of the electromagnetic signal. The circuit board has a series of conductive cells for suppressing at least one propagation mode propagating between the conductive member and circuit board over a frequency bandwidth range defined by a geometric arrangement of the conductive cells.

Claims

1. An antenna comprising:

a conductive member having an opening for radiating an electromagnetic signal, the conductive member having a first surface area bounded by a first perimeter; and

a high-impedance backing spaced apart from the conductive member by less than one quarter wavelength of the electromagnetic signal, the high-impedance backing having a second surface area, bounded by a second perimeter, commensurate in size with the first surface area, the high-impedance backing having an array of conductive cells arranged for suppressing at least one propagation mode from propagating between the conductive member and the high-impedance backing over a certain frequency range.

2. The antenna according to claim 1 wherein the opening comprises a generally rectangular slot.

3. The antenna according to claim 1 wherein the circuit board has a ground plane spaced apart from the conductive member by equal to or less than one-tenth of a free-space wavelength of the electromagnetic signal.

4. The antenna according to claim 1 wherein the conductive cells are arranged in an array facing the conductive member, wherein a subset of the conductive cells is electrically connected to a ground plane.

5. The antenna according to claim 1 wherein the circuit board comprises a ground plane and connective conductors, where at least some of the connective conductors connect the conductive cells to the ground plane.

6. The antenna according to claim 1 wherein the spatial region between the conductive member and the circuit board comprises an air dielectric region.

7. The antenna according to claim 1 wherein the spatial region between the conductive member and the circuit board is filled with a dielectric material.

8. The antenna according to claim 1 further comprising a transmission line for feeding the opening with an electromagnetic signal.

9. The antenna according to claim 8 wherein the transmission line comprises a coaxial cable connected to an edge of the opening between the ends of the opening so as to provide a desired impedance match to the transmission line.

10. The antenna according to claim 1 wherein the conductive cells and vias are arranged to suppress a longitudinal section magnetic mode and a longitudinal section electric mode as the propagation mode over the certain frequency range.

11. The antenna according to claim 1 wherein the conductive cells and vias are arranged to suppress the tangential magnetic field associated with the circuit board in the region between the circuit board and the conductive member.

12. The antenna according to claim 1 wherein the conductive cells are arranged to provide a high impedance ground plane over the frequency bandwidth range.

13. The antenna according to claim 1 wherein the opening comprises a slot with a longitudinal axis oriented substantially parallel to one principal axis of the conductive cells.

14. The antenna according to claim 1 wherein the opening comprises a slot with a longitudinal axis oriented at approximately a forty-five degree angle to one principal axis of the conductive cells.

15. The antenna according to claim 1 wherein metallic sidewalls are formed to provide a cavity region between the conductive member and the high-impedance backing.

16. The antenna according to claim 1 wherein the metallic sidewalls are formed form a linear series of vias.

18. The circuit board assembly according to claim 17 further comprising a transmission line for feeding the opening with the electromagnetic signal.

19. The circuit board assembly according to claim 17 wherein the opening comprises a generally rectangular slot.

20. The circuit board assembly according to claim 17 wherein the ground plane is spaced apart from the conductive member by equal to or less than one-twenty-fifth of a wavelength of the electromagnetic signal.

21. The circuit board assembly according to claim 17 wherein the conductive cells are arranged in an array facing the conductive member, wherein at least a subset of the conductive cells electrically is connected to the ground plane.

22. The circuit board assembly according to claim 17 further comprising connective conductors associated with the substrate, the connective conductors connecting at least some of the conductive cells to the ground plane.

23. The circuit board assembly according to claim 17 wherein a spatial region between the conductive member and the ground plane is filled with a dielectric material.

24. The circuit board assembly according to claim 17 wherein the transmission line comprises at least one of a stripline and a microstrip transmission line connected to an edge of the opening between the ends of the opening so as to provide a desired impedance match to the transmission line.

25. The circuit board assembly according to claim 17 wherein the transmission line comprises a waveguide coupled the opening between the so as to provide a desired impedance match to the waveguide.

26. The circuit board assembly according to claim 17 wherein the conductive cells are arranged to suppress the longitudinal section magnetic mode and the longitudinal section electric modes as the propagation modes over the certain frequency range.

27. The circuit board assembly according to claim 17 wherein the conductive cells and vias;

are arranged to suppress the tangential magnetic field associated with the circuit board in the region between the circuit board and the conductive member.

28. The circuit board assembly according to claim 17 wherein the conductive cells are arranged to provide a high impedance ground plane over the frequency bandwidth range.

29. The circuit board assembly according to claim 17 wherein the opening comprises a slot with a longitudinal axis oriented substantially parallel to one principal axis of the conductive cells.

30. The circuit board assembly according to claim 17 wherein the opening comprises a slot with a longitudinal axis oriented at approximately a forty-five degree angle to one principal axis of the conductive cells.

31. The circuit board assembly according to claim 17 wherein sides of the circuit board assembly are plated with a conductor to form a resonant cavity aperture (e.g., a radiating slot) antenna.

32. The antenna according to claim 17 wherein metallic sidewalls are formed to provide a cavity region between the conductive member and the high-impedance backing.

33. The antenna according to claim 17 wherein the metallic sidewalls are formed form a linear series of vias.

17. A circuit board assembly comprising:

a conductive member having an opening for radiating an electromagnetic signal;

a substrate for supporting a series of conductive cells and vias for suppressing at least one propagation mode from propagating between the conductive member and the substrate over a certain frequency range; and

a ground plane of the substrate spaced apart from the conductive member by less than one quarter wavelength of the electromagnetic signal.