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\xb0;
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 H2N;
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 \xb130%.
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\xb0 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 \xb130%.
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\xb0.
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.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A system for automatic landing of an aircraft on a landing runway, comprising:
an onboard image capture system carried by the aircraft and intended to capture a series of successive images of the ground;
an image analyzer for detecting in an image a landing runway and for determining in this image the characteristics of a segment P,\u03a9 connecting a planned point of impact P on the runway and a vanishing point \u03a9 of the image;
a measurement module for measuring a plurality of observables in an inertial frame tied to the runway, on the basis of the characteristics of the segment P,\u03a9, the plurality of observables comprising a first observable defined by the relative heading angle (\u03c8) of the aircraft with respect to a mid-axis of the runway, a second observable
(
\u0394
\ue89e
\ue89e
Y
\u0394
\ue89e
\ue89e
H
)
defined by the ratio of a lateral deviation to a vertical deviation of the position of the aircraft with respect to the point of impact and a third observable
(
\u0394
\ue89e
\ue89e
X
\u0394
\ue89e
\ue89e
H
)
defined by the ratio of a longitudinal deviation to the vertical deviation of the position of the aircraft with respect to the point of impact;
an estimator for estimating longitudinal (\u0394X), lateral (\u0394Y) and vertical (\u0394H) position deviations, expressed in the inertial frame, of the position of the aircraft with respect to the point of impact on the basis of the measurements of the first, second and third observables;
a guidance module for determining guidance orders for the aircraft on the basis of the longitudinal, lateral and vertical position deviations thus estimated, and of the relative heading angle.
2. The automatic landing system according to claim 1, wherein characteristics of the segment P,\u03a9 in the image are the angle \u03b6 between the straight line (P\u03a9) with the vertical of the image, the distance dy of the point P from a horizon line Dh and the distance dF between the orthogonal projection, Ph, of the point P on the horizon line and the vanishing point \u03a9.
3. The automatic landing system according to claim 2, wherein the image capture system comprises an onboard camera and that the relative heading angle \u03c8 is measured in the image by the measurement system by the relation:
\u03c8
=
arctan
\ue8a0
(
cos
\ue89e
\ue89e
\u03b8
\xb7
(
d
F
f
–
tan
\ue89e
\ue89e
\u03c6
\ue89e
\ue89e
tan
\ue89e
\ue89e
\u03b8
)
)
where f is the focal length of the onboard camera, \u03c6 is a roll angle and \u03b8 is the pitch angle of the aircraft.
4. The automatic landing system according to claim 3, wherein the second observable is measured in the image by the measurement module by:
\u0394
\ue89e
\ue89e
Y
\u0394
\ue89e
\ue89e
H
=
(
cos
\ue89e
\ue89e
\u03c6
\ue89e
\ue89e
sin
\ue89e
\ue89e
\u03c8
\ue89e
\ue89e
sin
\ue89e
\ue89e
\u03b8
–
sin
\ue89e
\ue89e
\u03c6
\ue89e
\ue89e
cos
\ue89e
\ue89e
\u03c8
)
–
(
sin
\ue89e
\ue89e
\u03d5
\ue89e
\ue89e
sin
\ue89e
\ue89e
\u03c8
\ue89e
\ue89e
sin
\ue89e
\ue89e
\u03b8
+
cos
\ue89e
\ue89e
\u03c6
\ue89e
\ue89e
cos
\ue89e
\ue89e
\u03c8
)
\ue89e
tan
\ue89e
\ue89e
\u03b6
tan
\ue89e
\ue89e
\u03b6
\ue89e
\ue89e
sin
\ue89e
\ue89e
\u03c6
\ue89e
\ue89e
cos
\ue89e
\ue89e
\u03b8
–
cos
\ue89e
\ue89e
\u03c6
\ue89e
\ue89e
cos
\ue89e
\ue89e
\u03b8
5. The automatic landing system according to claim 4, wherein the third observable is measured in the image by the measurement module by:
\u0394
\ue89e
\ue89e
X
\u0394
\ue89e
\ue89e
H
=
f
d
y
–
(
(
sin
\ue89e
\ue89e
\u03c8
\ue89e
\ue89e
cos
2
\ue89e
\u03b8
)
\ue89e
\u0394
\ue89e
\ue89e
Y
\u0394
\ue89e
\ue89e
H
+
cos
\ue89e
\ue89e
\u03b8
\ue89e
\ue89e
sin
\ue89e
\ue89e
\u03b8
)
cos
\ue89e
\ue89e
\u03c8
\ue89e
\ue89e
cos
2
\ue89e
\u03b8
6. The automatic landing system according to claim 5, wherein the longitudinal, lateral and vertical position deviations of the position of the aircraft with respect to the point of impact are estimated by the estimator by a dynamic model using as state equation {dot over (u)}(t)=v(t), where u(t)=(\u0394X, \u0394Y, \u0394H)T is a vector comprising the longitudinal, lateral and vertical position deviations at the instant t, v(t) is the velocity vector of the aircraft in an inertial frame, and as observation equation r(t)=g(u(t)) n(t), where r(t) is the vector of the third and second observables, and g is the function which to any vector u(t)=(\u0394X, \u0394Y, \u0394H)T maps the vector
g
\ue8a0
(
u
\ue8a0
(
t
)
)
=
(
\u0394
\ue89e
\ue89e
X
\u0394
\ue89e
\ue89e
H
\u0394
\ue89e
\ue89e
Y
\u0394
\ue89e
\ue89e
H
)
T
,
n(t) is a measurement noise vector.
7. The automatic landing system according to claim 1, wherein the aircraft guidance orders comprise a load factor setting and a roll rate setting, the guidance determining the load factor setting through the relation:
NzC=Kz+KVzVZ
where \u0394Z=\u2212\u0394H, VZ=()\u2032 is the vertical speed, and Kz, KVz are predetermined constants, and the roll rate setting through:
{dot over (\u03c6)}C=KY+K\u03c8\u03c8+K\u03c6\u03c6
where KY, K\u03c8 and K\u03c6 are predetermined constants.
8. The automatic landing system according to claim 1, furthermore comprising a flight controls computer suitable for determining controls to be applied to the actuators of the control surfaces of the aircraft so as to satisfy the guidance orders.
9. The automatic landing system according to claim 1, wherein the image analyzer furthermore determines the characteristics of at least one segment (A,\u03a9) from among the plurality of segments each connecting a vertex of the runway to the vanishing point \u03a9, the measurement module measures a plurality of additional observables in an inertial frame tied to the runway on the basis of the characteristics of the at least one segment, the plurality of additional observables comprising a first additional observable defined by the relative heading angle (\u03c8A) of the aircraft with respect to a straight line passing through the vertex of the runway and the vanishing point, a second additional observable
(
\u0394
\ue89e
\ue89e
Y
A
\u0394
\ue89e
\ue89e
Z
A
)
defined by a ratio of a lateral deviation to a vertical deviation of the position of the aircraft with respect to the vertex and a third additional observable
(
\u0394
\ue89e
\ue89e
X
A
\u0394
\ue89e
\ue89e
Z
A
)
defined by a ratio of a longitudinal deviation to the vertical deviation of the position of the aircraft with respect to the vertex, the estimator estimates additional longitudinal (\u0394XA), lateral (\u0394YA) and vertical (\u0394ZA) position deviations, expressed in the inertial frame, of the position of the aircraft with respect to the vertex of the runway on the basis of the measurements of the first, second and third additional observables, the automatic landing system furthermore comprising a consolidator for fusing the estimations of the longitudinal, lateral and vertical position deviations with the estimations of the additional longitudinal, lateral and vertical position deviations with respect to the vertex of the runway and providing consolidated longitudinal, lateral and vertical deviations in position between the aircraft and the planned point of impact.
10. The automatic landing system according to claim 9, wherein the guidance determines the aircraft guidance orders on a basis of the longitudinal, lateral and vertical position deviation estimations after they have been fused with the additional longitudinal, lateral and vertical position deviations.
11. The automatic landing system according to claim 9, wherein the estimator also provides on a basis of the estimations of the additional longitudinal, lateral and vertical position deviations, an estimation of the length andor of the slope of the landing runway.
12. A method of automatic landing of an aircraft on a landing runway, comprising:
capturing a series of successive images of the ground;
using an image analyzer for detecting in an image presence of a landing runway and for determining in the image characteristics of a segment P,\u03a9 connecting a planned point of impact P on the runway and a vanishing point \u03a9 of the image;
measuring a plurality of observables in an inertial frame tied to the runway on a basis of the image characteristics of the segment P,\u03a9, the plurality of observables comprising a first observable defined by relative heading angle (\u03c8) of the aircraft with respect to a mid-axis of the runway, a second observable
(
\u0394
\ue89e
\ue89e
Y
\u0394
\ue89e
\ue89e
H
)
defined by a ratio of a lateral deviation of position of the aircraft with respect to the point of impact and a third observable
(
\u0394
\ue89e
\ue89e
X
\u0394
\ue89e
\ue89e
H
)
defined by a ratio of a longitudinal deviation to a vertical ratio of position of the aircraft with respect to the point of impact;
estimating longitudinal (\u0394X), lateral (\u0394Y) and vertical (\u0394H) position deviations, expressed in the inertial frame, of the position of the aircraft with respect to the point of impact on a basis of the measurements of the first, second and third observables;
determining guidance orders for the aircraft on a basis of the longitudinal, lateral and vertical position deviations thus estimated, and of the relative heading angle.