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

• US 9,620,836 B2
• Filed: 12/17/2014
• Issued: 04/11/2017
• Est. Priority Date: 12/20/2013
• Status: Expired due to Fees

• Current Assignee: Centre National De La Recherche Scientifique, Centre National D'Etudes Spatiales, Thales SA
• Original Assignee: Centre National De La Recherche Scientifique, Centre National D'Etudes Spatiales, Thales SA
• Inventors: Jolly, Nicolas, Perigaud, Aurelien, Tantot, Olivier, Delhote, Nicolas, Bila, Stephane, Verdeyme, Serge, Pacaud, Damien, Estagerie, Laetitia
• Primary Examiner(s): LEE, BENNY T
• Application Number:
  US14/574,170
• Publication Number:
  US 20150180105A1
• Time in Patent Office: 846 Days
• Field of Search: 333202, 333235
• CPC Class Codes: H01P 1/2084 with dielectric resonators
• CPC Class Codes: H01P 1/2086 multimode
• CPC Class Codes: H01P 7/06 Cavity resonators
• CPC Class Codes: H01P 7/10 Dielectric resonators
• CPC Class Codes: H01P 7/105 Multimode resonators

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%.

Claims

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.