Waveguide cross-coupling filter with multiple parallel cavities

Patent metadata

Field	Value
Publication number	US-11646477-B2
Application number	US-202117190450-A
Country	US
Kind code	B2
Filing date	Mar 3, 2021
Priority date	Mar 3, 2021
Publication date	May 9, 2023
Grant date	May 9, 2023

Abstract

The disclosed radio frequency (RF) bandpass filter may include an RF transmission medium that defines (1) a plurality of cavities aligned parallel to each other along a major axis, where (a) each cavity includes planar surfaces that define (i) a first dimension aligned with the major axis and (ii) second and third dimensions aligned perpendicular to the major axis and each other, where the first dimension is shorter than the second and third dimensions and (b) each adjacent pair of cavities is coupled by an inter-cavity slot, (2) an RF inlet that couples a received RF signal to a first cavity at a first end of the plurality of cavities, and (3) an RF outlet that couples a filtered RF signal from a second cavity at a second end of the plurality of cavities externally to the filter. Various other filters and manufacturing methods thereof are also disclosed.

First claim

What is claimed is:

1. A radio frequency (RF) bandpass filter comprising an RF transmission medium that defines:
a plurality of cavities aligned parallel to each other along a major axis, wherein:
each of the cavities comprises a plurality of planar surfaces that define:
a first dimension aligned with the major axis, and
a second dimension and a third dimension that are aligned perpendicular to the major axis and each other, wherein the first dimension is shorter than the second dimension and the third dimension; and

each adjacent pair of cavities is coupled by an inter-cavity slot wherein:
each inter-cavity slot overlaps a portion of a consecutive inter-cavity slot in a manner that tunes a resonance frequency with a zero-transition corresponding with the overlap;

an RF inlet that couples an RF signal received at the RF bandpass filter to a first cavity of the plurality of cavities at a first end of the plurality of cavities; and
an RF outlet that couples a filtered RF signal from a second cavity of the plurality of cavities at a second end of the plurality of cavities opposite the first end externally to the RF bandpass filter.

2. The RF bandpass filter of claim 1 , wherein:
the RF bandpass filter further comprises a conductive housing; and
the RF transmission medium comprises air.

3. The RF bandpass filter of claim 2 , wherein the conductive housing comprises aluminum.

4. The RF bandpass filter of claim 2 , further comprising a conductive coating covering at least some portions of the conductive housing.

5. The RF bandpass filter of claim 1 , wherein the RF transmission medium comprises a material having a dielectric constant greater than one.

6. The RF bandpass filter of claim 5 , wherein the material comprises a ceramic.

7. The RF bandpass filter of claim 5 , further comprising a conductive coating covering at least some portions of the RF transmission medium.

8. The RF bandpass filter of claim 1 , wherein the plurality of cavities comprises the first cavity, the second cavity, a third cavity adjacent the first cavity, and a fourth cavity adjacent the third cavity.

9. The RF bandpass filter of claim 8 , wherein:
each inter-cavity slot is sized, shaped, and positioned relative to the consecutive inter-cavity slot to create the zero transition; and
each inter-cavity slot is positioned perpendicular relative to at least one of an immediately preceding or an immediately subsequent inter-cavity slot.

10. The RF bandpass filter of claim 9 , wherein the zero-transition created by the inter-cavity slots results in a low S-parameter gain valley of approximately −100 dB.

11. The RF bandpass filter of claim 8 , wherein the plurality of cavities further comprises a fifth cavity adjacent the third cavity, a sixth cavity adjacent the fourth cavity, a seventh cavity adjacent the fifth cavity, and an eighth cavity adjacent the sixth cavity.

12. The RF bandpass filter of claim 1 , wherein each cavity of the plurality of cavities approximates a rectangular cuboid.

13. The RF bandpass filter of claim 12 , wherein the first cavity further defines:
a first notch occupying a first corner region of the rectangular cuboid;
a second notch occupying a second corner region of the rectangular cuboid diagonally opposite the rectangular cuboid from the first corner region;
a third corner region between the first corner region and the second corner region; and
a fourth corner region diagonally opposite the rectangular cuboid from the third corner region.

14. The RF bandpass filter of claim 13 , wherein a subsequent cavity adjacent the first cavity further defines:
a first corner region, a second corner region, a third corner region, and a fourth corner region aligning along the major axis with the first corner region, the second corner region, the third corner region, and the fourth corner region, respectively, of the first cavity;
a first notch occupying the third corner region of the subsequent cavity; and
a second notch occupying the fourth corner region of the subsequent cavity.

15. The RF bandpass filter of claim 1 , wherein at least one of the RF inlet and the RF outlet is configured to be coupled with a waveguide.

16. An RF duplexer that comprises:
an antenna port;
a transmission port;
a reception port;
a first bandpass filter that couples the transmission port to the antenna port; and
a second bandpass filter that couples the reception port to the antenna port;
wherein each of the first bandpass filter and the second bandpass filter comprises an RF transmission medium that defines a plurality of cavities aligned parallel to each other along a major axis, wherein:
each of the cavities comprises a plurality of planar surfaces that define:
a first dimension aligned with the major axis, and
a second dimension and a third dimension that are aligned perpendicular to the major axis and each other, wherein the first dimension is shorter than the second dimension and the third dimension; and

each adjacent pair of cavities is coupled by an inter-cavity slot, wherein:
each inter-cavity slot overlaps a portion of a consecutive inter-cavity slot in a manner that tunes a resonance frequency with a zero-transition corresponding with the overlap.

17. A method of manufacturing a radio frequency (RF) bandpass filter, the method comprising:
creating a set of conductive plates; and
assembling the set of conductive plates side-by-side along a major axis to form the RF bandpass filter, wherein the RF bandpass filter comprises an RF transmission medium that defines:
a plurality of cavities aligned parallel to each other along the major axis, wherein:
each of the cavities comprises a plurality of planar surfaces that define:
a first dimension aligned with the major axis, and
a second dimension and a third dimension that are aligned perpendicular to the major axis and each other, wherein the first dimension is shorter than the second dimension and the third dimension; and

each adjacent pair of cavities is coupled by an inter-cavity slot, wherein:
each inter-cavity slot overlaps a portion of a consecutive inter-cavity slot in a manner that tunes a resonance frequency with a zero-transition corresponding with the overlap.

18. The method of claim 17 , wherein the RF transmission medium further comprises:
an RF inlet that couples an RF signal received at the RF bandpass filter to a first cavity at a first end of the plurality of cavities; and
an RF outlet that couples a filtered RF signal from a second cavity at a second end of the plurality of cavities opposite the first end externally to the RF bandpass filter.

19. The method of claim 17 , wherein the set of conductive plates comprises aluminum.

20. The method of claim 17 , further comprising coating at least a portion of the set of conductive plates with a conductive layer.

Assignees

• Meta Platforms Inc

Inventors

• Tabatabai Farbod
• Alijagic Haris

Classifications

• H01P1/208 Primary

  Cascaded cavities; Cascaded resonators inside a hollow waveguide structure (H01P1/205 takes precedence) · CPC title

• H01P1/2138 Primary

  using hollow waveguide filters (H01P1/2131 takes precedence) · CPC title

• H01P11/007

  Manufacturing frequency-selective devices (resonators H01P11/008) · CPC title

• H01P11/002

  Manufacturing hollow waveguides · CPC title