Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
  • H01P7/00—Resonators of the waveguide type
  • H01P7/06—Cavity resonators

Definitions

• the present invention relates to filtering devices in the microwave domain, of the type having a metal cavity with dielectric inserts.
• the invention particularly advantageously finds application for filtering in the field of telecommunications by satellites.
• Metal cavities have long been used for filtering hyper frequencies. Recent studies have shown that it is advantageous, in order to improve the electrical performance of the resonators constituted by such metal cavities, to charge them by dielectric inserts extending transversely in the cavity. In this respect, it is advantageous to refer to the following different publications:
• the dielectric inserts indeed make it possible to distance the strong electromagnetic fields from the metal end walls of the cavity, and therefore to confine the energy in the central part of the cavity.
• An object of the invention is to provide a filtering device of the type having a metal cavity with dielectric inserts, which makes it possible to solve this problem and which, moreover, has particularly satisfactory properties, in particular at high powers.
• Another object of the invention is therefore to propose a device with a metal cavity in which the dielectric inserts define several resonators allowing said device to carry out multi-pole filtering and in which means are provided for coupling between these different resonators.
• metallic irises extending transversely either at the level of the end walls of the cavity, that is to say inside thereof between two resonators defined by dielectric inserts, made it possible to produce particularly satisfactory couplings and to solve the problem due to the coupling of the resonant parasitic modes in the dielectric inserts.
• the invention provides a filtering device comprising a metal cavity closed by two end walls extending transversely with respect to the axis of said cavity, as well as at least two dielectric inserts defining a resonator in said cavity, characterized in that it comprises at least one coupling iris which also extends transversely with respect to said axis.
• this device comprises two coupling irises distributed respectively over one and the other of the two end walls and which couple said cavity with metal waveguides superimposed on said end walls.
• it may include a coupling iris extending transversely between two resonators each defined between two dielectric inserts.
• - Figure 1 schematically illustrates a possible application for the invention
• - Figure 2 is a graph on which the external coupling coefficient of the device illustrated in Figure 1 has been plotted, as a function of the length of the irises of this device;
• FIG. 1 schematically illustrates another possible application for the invention
• - Figure 4 is a graph on which the intercavity coupling coefficient of the device illustrated in Figure 3 has been plotted, as a function of the length of the iris of this device.
• the coupling device illustrated in FIG. 1 comprises a metal cavity 1, which is of the cylindrical type.
• This cavity 1 is defined by a cylindrical side wall 2 and by two end walls 3a and 3b which close said cavity 1 by extending transversely relative to its axis.
• FIG. 2 gives, for different lengths of rectangular coupling iris, the values of the external quality coefficient of a filtering device of the type illustrated in FIG. 1. It is recalled that from a point electrically, a coupling device as illustrated in FIG. 1 is characterized by:
• Q "- Q ⁇ 1 + Q; 1 The values given for Q e in FIG. 2 correspond to the case of a cylindrical metallic cavity 39.7 mm in diameter having dielectric inserts 4a, 4b made of sapphire with a thickness of 1.92 mm, the distance separating these inserts dielectric 4a, 4b of the walls 3a and 3b being 6.4 mm, the height separating these two dielectric inserts being 12.8 mm, the coupling irises being 2 mm thick, with a width of
• the metal guides 6a, 6b being guides of type G90 with a height of
• the invention is not limited to cases where the cylindrical cavity is of the cylindrical type, but also applies in the case of metal cavities having another shape.
• FIG. 3 a metal cavity 11, of cylindrical type, which has a plurality of dielectric inserts 14a to 14d, which define in said cavity, has been illustrated.
• resonators 15a, 15b are coupled via a metal iris 17, for example of rectangular, circular or cross shape.
• the metallic iris 17 is advantageously placed at the level of the middle height of the cavity 11, so that said cavity 11 has a structure which is symmetrical on either side of said iris metallic 17.
• the graph of FIG. 4 shows the intercavity coupling values of a structure of the type illustrated in FIG. 3, in the case of a metal cavity 11 39.7 mm in diameter having four dielectric inserts 14a to 14d constituted by sapphire pellets with a thickness of 1.92 mm, the inserts 14a (resp. 14c) and 14b (resp. 14d) being separated by a height of 12.8 mm, the height of separation between the dielectric pads and the metal end walls 13a, 13b of the cavity 11 or the coupling iris 17 disposed inside the cavity 11 being 6.4 mm, the coupling iris 17 having a rectangular opening a 2 mm thick, 1 mm wide and variable length.
• This variation does not entail coupling of the modes of the dielectric inserts and the environment. electromagnetic of the inserts is not modified.
• the filtering devices which have just been described have conventional coupling values for this type of device and satisfy the usual insulation constraints.

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• 1996
  • 1996-11-05 FR FR9613441A patent/FR2755544B1/fr not_active Expired - Fee Related
• 1997
  • 1997-11-03 CA CA002271074A patent/CA2271074A1/fr not_active Abandoned
  • 1997-11-03 EP EP97913235A patent/EP0937310A1/de not_active Ceased
  • 1997-11-03 US US09/297,665 patent/US6211752B1/en not_active Expired - Fee Related
  • 1997-11-03 WO PCT/FR1997/001962 patent/WO1998020576A1/fr not_active Ceased

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