Bandpass microwave filter tunable by a 90 degree rotation of a dielectric element between first and second positions

Patent metadata

Field	Value
Publication number	US-9620836-B2
Application number	US-201414574170-A
Country	US
Kind code	B2
Filing date	Dec 17, 2014
Priority date	Dec 20, 2013
Publication date	Apr 11, 2017
Grant date	Apr 11, 2017

Abstract

A frequency tunable microwave bandpass filter comprises a resonator, including: a cavity with conducting wall substantially cylindrical with axis Z having height H, and partially closed at both ends; and a dielectric element inside the cavity. The resonator resonates at two perpendicular polarizations having distributions of electromagnetic field in the cavity deduced from eachother by 90° rotation. The element rotates about an axis substantially perpendicular to axis Z, between a first and second position. The element comprises a first end wherein: in a first position the element is disposed substantially in a plane perpendicular to axis Z and the center of the first end is disposed at a height in the cavity corresponding substantially to an electric field minimum; and in a second position the element is substantially parallel to Z and the first end is disposed in a plane corresponding to an electric field maximum within +/−30%.

First claim

The invention claimed is:

1. A bandpass dual mode filter for microwave-frequency wave, the bandpass dual mode filter being frequency tunable, the bandpass dual mode filter comprising:
at least one resonator, each said at least one resonator including:
a cavity having a conducting wall substantially cylindrical in relation to an axis Z having a height H, a position along the axis Z being labelled by an abscissa z lying between 0 and H, the cavity being at least partially closed at two ends, and
a dielectric element disposed inside the cavity;

said at least one resonator resonating according to a mode for which two perpendicular polarizations respectively have distributions of the electromagnetic field in the respective cavity, said distributions of the two perpendicular polarizations being obtained from one another by a rotation of the respective dielectric element by 90° around an axis of symmetry of the at least one resonator;
said mode having in said respective cavity N maxima and N+1 minima of the electromagnetic field, N being an integer, said N maxima and N+1 minima are situated substantially in a plane perpendicular to the axis Z, the two ends of the respective substantially cylindrical conducting wall at the abscissae z=0 and z=H corresponding to respective electromagnetic field minima, successive minima and maxima in the N maxima and N+1 minima being spaced apart by a separation distance H/2N;
the at least one resonator further including:
means of rotation adapted for setting each said dielectric element into rotation in relation to an axis Ro substantially perpendicular to the axis Z, between at least a first and a second position;
each said dielectric element comprising at least one first end such that:
in a first position, each said dielectric element is disposed substantially in a plane perpendicular to the axis Z and a center of said at least one first end is disposed at a height in the cavity corresponding substantially to a minimum of the electromagnetic field,
in a second position, each said dielectric element is substantially parallel to the axis Z and said first end is disposed in a plane corresponding to an maximum of the electromagnetic field to within +/−30%.

2. The bandpass dual mode filter according to claim 1 , in which each said dielectric element has a central part of an elongated shape and a first end having a greater cross-section than a cross-section of the central part.

3. The bandpass dual mode filter according to claim 1 , in which each said dielectric element in the second position has a shape such that a volume traversed by the electromagnetic field in a polarization is substantially identical to a volume traversed by the electromagnetic field in an orthogonal polarization.

4. The bandpass dual mode filter according to claim 1 , in which each said dielectric element in the second position has a shape that is invariant under a rotation of 90° about the axis Z.

5. The bandpass dual mode filter according to claim 1 , in which a shape of each said dielectric element comprises two orthogonal symmetry planes, a symmetry plane in the two orthogonal symmetry planes coinciding with a plane comprising a polarization axis and the axis Z when each said dielectric element is in the second position.

6. The bandpass dual mode filter according to claim 1 , in which each said dielectric element comprises a second end such that:
in the first position, a center of the said second end is disposed at a height in the cavity corresponding substantially to a minimum of the electromagnetic field,
in the second position, the second end is disposed in a plane corresponding to a maximum of the electromagnetic field to within +/−30%.

7. The bandpass dual mode filter according to claim 1 , in which said respective substantially cylindrical wall has a base chosen from among a circle and a square.

8. The bandpass dual mode filter according to claim 1 , in which an angle of rotation, relative to an axis of rotation Ro of each said dielectric element, between the first position and the second position is substantially equal to 90°.

9. The bandpass dual mode filter according to claim 1 , in which an axis of rotation Ro of each said dielectric element coincides with the axis Z.

10. The bandpass dual mode filter according to claim 1 , in which an axis of rotation Ro of each said dielectric element is situated at the abscissa z corresponding to a minimum of the electromagnetic field.

11. The bandpass dual mode filter according to claim 1 , in which the means of rotation include a rod along an axis of rotation Ro of each said dielectric element, said rod being rigidly attached to each said dielectric element and comprising a dielectric material.

12. The bandpass dual mode filter according to claim 1 , in which N=2.

13. The bandpass dual mode filter according to claim 1 , comprising a plurality of resonators and coupling means adapted for coupling together two consecutive resonators.

14. The bandpass dual mode filter according to claim 13 , further comprising linking means adapted for making all respective angles of rotation associated with the means of rotation equal.

15. The bandpass dual mode filter according to claim 14 , wherein the means of rotation include a rod along the axis of rotation Ro rigidly attached to each said dielectric element, and wherein the linking means comprise the rod rigidly attached to a plurality of dielectric elements disposed along the rod.

16. The bandpass dual mode filter according to claim 14 , further comprising additional dielectric elements disposed inside the coupling means and rigidly attached to the linking means.

17. A microwave circuit comprising at least one bandpass dual mode filter according to claim 1 .

Assignees

• Thales Sa
• Centre Nat Rech Scient
• Centre Nat D'Etudes Spatiales

Inventors

• Jolly Nicolas
• Perigaud Aurelien
• Tantot Olivier
• Delhote Nicolas
• Bila Stephane
• Verdeyme Serge
• Pacaud Damien
• Estagerie Laetitia

Classifications

• H01P7/105

  Multimode resonators · CPC title

• H01P1/2086 Primary

  multimode · CPC title

• H01P7/10

  Dielectric resonators · CPC title

• H01P1/2084

  with dielectric resonators · CPC title

• H01P7/06

  Cavity resonators · CPC title