Patent Application
20120249267
The invention pertains to transmission of radio frequency signals and to filters used in transmission of radio frequency signals.
In-line filters are well known for use in radio frequency transmission lines. Examples of radio frequency filters include low pass filters. Further examples of low pass filters include generally cylindrical conductive structures, which may have changing outer diameters, and which may be surrounded by a dielectric material. Such filters have been known to be supported by a housing block having a channel into which the filter is placed, with a flat cover mounted over the top of the channel and the filter.
A brief summary of various exemplary embodiments is presented in this section. Some simplifications and omissions may be made in the following summary, which is intended to highlight and introduce some aspects of the various exemplary embodiments, but not to limit the scope of the invention. Detailed descriptions of a preferred exemplary embodiment adequate to allow those of ordinary skill in the art to make and use the inventive concepts will follow in later sections.
Various exemplary embodiments relate to a radio frequency (RF) filter assembly, comprising: a filter component; a housing having a groove to receive the filter component; a cover mounted to the housing to cover the groove; and an elastomeric element disposed between the cover and the filter.
The elastomeric member can include two elastomeric members each in the shape of a rod, and may be made of silicone. The groove can define a semi-circular u-shaped surface and two side wall surfaces, each being on one side of the u-shaped surface. The tubular elastomeric member can be in contact with an outer surface of the filter, an inner surface of the channel, and an inner surface of the plate. The elastomeric member may have two parallel rod portions, connected to each other by a plurality of cross bar portions. The assembly may also have an extension block disposed in between the elastomeric member and the filter, having a lower surface having a concave curved portion.
Other exemplary embodiments relate to a method of stabilizing a radio frequency (RF) filter assembly, comprising: providing a filter component, a housing having a groove to receive the filter component, and a cover mounted to the housing to cover the groove; and compressing an elastomeric element disposed between the cover and the filter.
Other exemplary embodiments relate to a radio frequency (RF) filter assembly, comprising: a filter component; a housing having a groove to receive the filter component; a cover mounted to the housing to cover the groove; and stabilizing means, such as an elastomeric member, disposed between the cover and the filter.
In order to better understand various exemplary embodiments, reference is made to the accompanying drawings, wherein:
Various embodiments will now be described with reference to the drawing figures, including reference numerals relating to the various parts.
The main filter component 16 is surrounded by a dielectric material 22. In the illustrated example, the dielectric material may be any suitable material such as, for example, a melt-porcessible flouropolymer such as a heat shrink applied FEP (fluorinated ethylene propylene) material, in some cases with the dielectric outer material having been applied around the main filter component 16 using a heat gun. Alternatively, other dielectric surrounding materials may be used, and may be implemented or applied in different methods.
Returning to
The housing 24 has sides 26 and a bottom surface 28, but may be any external shape and can be surrounded by and be a part of a cavity filter. The housing 24 also has two flat top mounting surfaces 30 which will be described in more detail below. The housing 24 further includes a channel 32 (also referred to herein as a groove) which is configured to receive and support the filter 10. In the illustrated example, the channel 32 has a lower surface 33 which is a semi-circle when viewed as an end view, and has two flat side surfaces 34. The radius of the semi-circular lower surface 33 may be selected to be dimensionally close to the largest outer radius of the filter 10. This can provide an advantage in some examples by which the largest outer surface of the filter 10 rests with the desired closeness to the housing 24, around approximately 180° of the 360° circumference of the filter 10. In other embodiments, the lower portion of the channel 32 may be square, in which case only three substantially tangential contact points with the filter 10 are provided between the filter 10 and the housing 24.
The assembly of
As will be described in further detail below, the elastomeric elements 44 in some embodiments may provide a benefit of being compressed between the cover 36 and the filter 10 in such a way as to resiliently position the filter 10 against the lower surface 32 of the channel. Although two parallel elastomeric elements 44 are shown, with each elastomeric element spanning essentially the entire length of the housing 24, a single elastomeric element 44, or a larger number of elastomeric elements, may be employed and may run for a shorter portion of the housing.
In
The reaction forces described above are by way of examples in some embodiments only. The materials and geometries are also examples and can be selected to provide a desirable degree of compression force. In some instances, it may be desirable to select the compression force so that it is low enough so that the cover 36 is not unduly deflected upwards away from the housing 24. In some instances, it may be desirable to avoid undue upward deflection of the cover 36 so that the lower surface of the cover 36 remains flush or flat against the upper surface 30 of the housing 24, thus providing a desired degree of electrical contact between the cover 36 and the housing 24.
Due to the compressive forces, the filter 10 is stabilized with respect to the housing 24, and in some cases will thus tend to remain in place to a desired degree when subjected to vibrations or thermal dimensional changes of the filter 10 and/or housing 24 with respect to each other.
In the illustrated embodiments, the elastomeric members 44 have a cylindrical tube shape with a circular outer profile. However, the outer profile of the elastomeric members may be any other shape including, for example, triangular, square, hexagonal or other shapes which may have uneven outer surfaces.
In the illustrated embodiments, the elastomeric members 44 are shown as being a separate component from the filter. However, in some other embodiments the elastomeric components may be permanently or semi-permanently attached to the outside of the filter, for example, by being adhesively attached on pre-manufactured onto the filter. For example, elastomeric components may be pre-molded onto an outer surface of the filter along with or after the application of the dielectric layer.
Although the various exemplary embodiments have been described in detail with particular reference to certain exemplary aspects thereof, it should be understood that the invention is capable of other embodiments and its details are capable of modifications in various obvious respects. As is readily apparent to those skilled in the art, variations and modifications can be affected while remaining within the spirit and scope of the invention. Accordingly, the foregoing disclosure, description, and figures are for illustrative purposes only and do not in any way limit the invention, which is defined only by the claims.
