The present Application is based on International Application No. PCT/EP2007/055410, filed on Jun. 1, 2007, which in turn corresponds to French Application No. 06 52011 filed on Jun. 2, 2006, and priority is hereby claimed under 35 USC §119 based on these applications. Each of these applications are hereby incorporated by reference in their entirety into the present application.
The invention relates to a microwave waveguide, to its production process and to its application to a microwave filter, notably a very high-power microwave filter. The invention is applicable more particularly to filters comprising length-adjustable short-circuited transmission lines, called stubs in the art, and used for producing impedances. The invention also relates to a microwave transmit/receive station using the microwave filter applicable notably in the space field.
In certain fields of application, there is a need for microwave filters of very high power. This is the case for example in the space field, where the transmit power must be particularly high and where the filters used must be effective at high power levels in order to provide a maximum transmit power. This is the case for example in direct transmission systems by satellite. The satellite must then be able to transmit with a maximum power. However, the invention is applicable in any other field in which high-power operation is required.
When a waveguide is used in a vacuum (for space applications) and in the case of high-power waveguides, it is possible to initiate an electron avalanche, called a multipactor effect, in certain zones of the waveguide.
This multipactor effect is caused by a concentration of the electromagnetic field which tears electrons out of the walls of the waveguide. The electrons are then accelerated toward the opposite wall of the waveguide. The impact of these electrons on the latter wall causes in turn electrons to be torn therefrom, and so on. An electron avalanche phenomenon thus occurs, which degrades the electrical performance of the waveguide and may lead to it being destroyed.
This phenomenon therefore occurs notably in the space field in which the waveguides operate in a vacuum in the absence of air molecules.
The multipactor power level is the maximum power at which a component can be used without initiating the multipactor effect. This threshold power can be calculated between two parallel plates from the following equation:
P=(1/VMF2)×(Vmulti2/2Z0)
where
To reduce this multipactor effect, it is possible either to move the walls of the waveguide further apart in order to increase the Vmulti or to reduce the electric field concentration in order to reduce the VMF.
Both these solutions pose problems. If moving the walls of the waveguide further apart is envisioned, the operating frequency range is reduced and the device will have difficulties matching the waveguide for all frequencies in the operating range.
To reduce the concentration of the electric field at the critical point, it is necessary to modify the topology of the devices, or even, in the case of filters, to change the type of filter.
The object of the invention is to solve these problems and to provide a microwave waveguide and microwave filters in which the multipactor power level has been notably increased.
The invention therefore relates to a process for the production of a microwave waveguide comprising the following steps:
This process is applicable to the production of a microwave filter comprising length-adjustable short-circuited transmission lines, such as stubs. This process includes:
Advantageously, each enlargement is located at a distance λg/4 from the short-circuit zone of the stub, λg being a guided wavelength lying within the operating wavelength range of the filter.
The invention also relates to a microwave filter produced by this process. Each stub takes the form of a Latin cross in which the horizontal arms perpendicular to the axis of the stub correspond to said enlargements.
According to one embodiment of the invention, the horizontal arms are of unequal lengths.
According to another embodiment of the invention, at least one horizontal arm has sections of different dimensions. The section closest to the axis of the stub is larger than the section or sections further away from the axis of the stub.
According to another embodiment, at least one horizontal arm has sections of different dimensions, the section closest to the axis of the stub being smaller than the section or sections further away from the axis of the stub.
It is also possible for the end face of each horizontal arm to be inclined to the axis of the stub.
According to another embodiment of the invention, it is also possible for the end face of each horizontal arm to have a curved shape.
The invention is also applicable to a microwave transmit/receive station using the microwave filter thus described. This station therefore comprises:
Still other objects and advantages of the present invention will become readily apparent to those skilled in the art from the following detailed description, wherein the preferred embodiments of the invention are shown and described, simply by way of illustration of the best mode contemplated of carrying out the invention. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious aspects, all without departing from the invention. Accordingly, the drawings and description thereof are to be regarded as illustrative in nature, and not as restrictive.
The present invention is illustrated by way of example, and not by limitation, in the figures of the accompanying drawings, wherein elements having the same reference numeral designations represent like elements throughout and wherein:
a, a representation of a waveguide for explaining the subject of the invention;
b, an exemplary embodiment of a waveguide according to the invention;
a and 4b, exemplary embodiments of a microwave filter having stubs according to the invention;
a to 5e, various embodiments of the stubs of a microwave filter;
a to 6c and 7a to 7c, alternative embodiments of stubs according to the invention; and
a shows a waveguide g1 for propagating a microwave. As is known, variations in electromagnetic energy levels can be detected in the waveguide. Variations in energy levels are illustrated in
To remedy this, the invention therefore provides a way of identifying and locating the zones, such as Z1, in which there may be energy concentrations, and of enlarging the waveguide in these zones.
b therefore shows an example of a waveguide according to the invention in which the walls of the waveguide g1 have an enlargement el1. This enlargement is produced in such a way that the energy concentration in the zone z1 cannot give rise to a multipacter effect.
The invention is also applicable to the production of microwave filters.
It has been found that the stubs of the filters are the site of electromagnetic energy concentrations. To avoid the creation of multipacter effects in the stubs, an enlargement is therefore provided in the energy concentration zones.
In a stub, such as st1 in
An example of the invention applied to a microwave filter having stubs will now be described with reference to
The invention makes it possible to avoid this multipactor effect. To do this, as shown in
However, in certain cases the distance between stubs may not allow these enlargements to be provided in a filter of the type shown in
The enlargements may take different forms.
b to 7c give various examples of these forms.
The aim is to avoid creating a multipactor effect in a stub su1 shown in
b and 5c show stubs su1 having enlargements eu1 and eu2 as described above. The enlargement eu2 is larger than the enlargement eu1 and is provided for a higher initial energy concentration in the stub of
The stub of
The enlargements eu4 and eu′4 of
In these stubs, the enlargements are symmetrical with respect to the axis X of the stubs.
a shows a stub having an enlargement eu5, which itself has an enlargement eu′5 of larger size. The enlargements are symmetrical with respect to the axis X of the stub and the enlargement eu′5 is symmetrical with respect to the axis Y of the enlargement eu5.
b shows a stub of the same type as that in
c shows a stub that has an enlargement e″7 on one side of the axis X of the stub and it has, on the other side of the axis X, an enlargement eu7 which itself has an enlargement eu′7 of larger size.
Provision is therefore made for producing enlargements that are not symmetrical with respect to the axes X of the stubs.
Moreover, provision may be made for the faces of the ends of the enlargements furthest away from the axis X of the stub not to be parallel to the axis X. This is shown in
There may also be provision for the walls of the enlargements to have curved surfaces, as shown in
According to another embodiment shown in
The various enlargement shapes described above, preventing the multipactor effect, were described within the context of an application to stubs of a filter, but they could be applied to any microwave waveguide.
By providing stubs as described in the invention, the power level of the filter may be very greatly increased.
Moreover, the stubs as described in the invention have a volume larger than a stub without an enlargement, as shown in
An example of such a filter applied in a transmit/receive unit on board a satellite will now be described with reference to
Such a unit must be able to transmit and receive signals at different energy levels. It must transmit at a maximum energy level and it must receive relatively attenuated signals.
The unit shown in
Diplexer filters DXH and DXV, for horizontal polarization and vertical polarization respectively, are connected to the ports e1 and e2 of a polarization mode splitter/combiner OMT, which is connected via its port e3 to the transmit/receive horn CO.
The receive filters FiRxH and FiRxV may be of relatively low operating power. In contrast, the transmit filters FiTxH and FiTxV must be able to operate at high power levels.
The transmit filters FiTxH and FiTxV are designed according to the invention to allow high power levels. It is then possible to produce a unit as shown in
The invention therefore makes it possible to obtain, in a waveguide and more particularly in a filter:
It will be readily seen by one of ordinary skill in the art that the present invention fulfils all of the objects set forth above. After reading the foregoing specification, one of ordinary skill in the art will be able to affect various changes, substitutions of equivalents and various aspects of the invention as broadly disclosed herein. It is therefore intended that the protection granted hereon be limited only by definition contained in the appended claims and equivalents thereof.
Number | Date | Country | Kind |
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06 52011 | Jun 2006 | FR | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP2007/055410 | 6/1/2007 | WO | 00 | 3/18/2009 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2007/141213 | 12/13/2007 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
2939037 | Jepsen | May 1960 | A |
4862186 | Strider | Aug 1989 | A |
5051713 | Yokota | Sep 1991 | A |
Number | Date | Country |
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17 66 579 | Aug 1971 | DE |
63010802 | Jan 1988 | JP |
Number | Date | Country | |
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20090237184 A1 | Sep 2009 | US |