BANDPASS MICROWAVE FILTER TUNABLE BY ROTATION OF A DIELECTRIC ELEMENT

• US 20150180105A1
• Filed: 12/17/2014
• Published: 06/25/2015
• Est. Priority Date: 12/20/2013
• Status: Active Grant

• 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, ESTAGERIE, Laetitia, BILA, Stephane, VERDEYME, Serge, PACAUD, Damien
• Granted Patent: US 9,620,836 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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 each other 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 centre 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 filter for microwave-frequency wave, frequency tunable, comprising at least one resonator, each resonator comprising:

a cavity having a conducting wall substantially cylindrical in relation to an axis Z having a height H, a position z along the axis Z being labelled by an abscissa z lying between 0 and H, and being at least partially closed at both ends and, and at least one dielectric element disposed inside the cavity;

said resonator resonating according to a mode for which two perpendicular polarizations respectively have distributions of the electromagnetic field in the cavity that are deduced from one another by a rotation of 90°

;

said mode having in said cavity N maxima and N+1 minima of electric field which are situated substantially in a plane perpendicular to the axis Z, the two ends of the cylinder respectively at the abscissae z=0 and z=H corresponding to electric field minima, successive minima and maxima being spaced apart by a separation distance H/2N;

further comprising;

means of rotation adapted for setting said element into rotation in relation to an axis R substantially perpendicular to the axis Z, between at least a first and a second position;

said element comprising at least one first end such that;

in a first position the said element is disposed substantially in a plane perpendicular to the axis Z and the centre of said first end is disposed at a height in the cavity corresponding substantially to a minimum of the electric field, in a second position said element is substantially parallel to Z and said first end is disposed in a plane corresponding to an electric field maximum to within ±

30%.

2. The filter according to claim 1, in which the dielectric element has a central part of elongate shape and a first end having a greater cross-section than a cross-section of the central part.

3. The filter according to claim 1, in which said element in the second position has a shape such that the volume traversed by a polarization is substantially identical to the volume traversed by the orthogonal polarization.

4. The filter according to claim 1, in which said element in the second position has a shape such that it is invariant under rotation of 90°

about the axis Z.

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

6. The filter according to claim 1, in which said element comprises a second end such that:

in the first position the centre of the said second end is disposed at a height in the cavity corresponding substantially to a minimum of the electric field,

in the second position the said second end is disposed in a plane corresponding to an electric field maximum to within ±

30%.

7. The filter according to claim 1, in which the said substantially cylindrical wall has a director curve chosen from among a circle, a square.

8. The filter according to claim 1, in which the angle of rotation in relation to the axis R between the first position and the second position is substantially equal to 90°

.

9. The filter according to claim 1, in which the axis of rotation R is concurrent with the axis Z.

10. The filter according to claim 1, in which the axis of rotation is situated at an abscissa z corresponding to an electric field minimum.

11. The filter according to claim 1, in which the means of rotation comprise a rod along the axis R rigidly attached to the element and comprising a dielectric material.

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

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

14. The filter according to claim 13, further comprising linking means adapted for equalizing the respective rotations of the resonator means of rotation.

15. The filter according to claim 14, in which the linking means comprise the said rod rigidly attached to a plurality of elements disposed along the rod.

16. The 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 filter according to claim 1.