Methods and devices for grounding deep drawn resonators

Abstract

Difficulties in grounding a non-integral, deep drawn resonator (DDR) to the filter body of a cavity may be substantially eliminated by preventing the movement of the DDR away from a grounding contact area on the filter body. The addition of a compression plate and stop limiter in the connection of the non-integral DR to the filter body helps insure that any such movement is eliminated or substantially reduced.

Claims

1. A cavity filter comprising: a filter body; a resonator connected to the filter body and in contact with the filter body at a contact area to ground the resonator, said resonator including a bottom portion having a stop limiter; and a compression plate positioned such that the stop limiter is located between the compression plate and the filter body to substantially eliminate movement of the resonator away from the contact area of the filter body.

2. The cavity filter as in claim 1, wherein the resonator comprises a deep drawn resonator.

3. The cavity filter as in claim 1, wherein the cavity filter is a part of a tower mounted amplifier or antenna.

4. The cavity filter as in claim 1, wherein the compression plate comprises a metallic material.

5. The cavity filter as in claim 1, wherein the compression plate comprises a non-ferrous metallic material.

6. The cavity filter as in claim 1, wherein the resonator operates over a range of frequencies selected from at least 698 MHz to 960 MHz and 1700 MHz to 2700 MHz.

7. The cavity filter as in claim 1, wherein the stop limiter is configured as a stepped stop limiter.

8. A method for grounding a resonator comprising: connecting a filter body and the resonator so as to place the resonator in contact with the filter body at a contact area, the resonator comprising a bottom portion having a stop limiter to ground the resonator; and positioning a compression plate such that the stop limiter is located between the compression plate and the filter body to substantially eliminate movement of the resonator away from the contact area of the filter body.

9. The method as in claim 8 further comprising configuring the stop limiter as a stepped stop limiter.

10. The method as in claim 8, wherein the resonator comprises a deep drawn resonator.

11. The method as in claim 8, wherein the cavity filter is a part of a tower mounted amplifier or antenna.

12. The method as in claim 8, wherein the compression plate comprises a metallic material.

13. The method as in claim 8, wherein the compression plate comprises a non-ferrous metallic material.

14. The method as in claim 8, further comprising operating the resonator over a range of frequencies selected from at least 698 MHz to 960 MHz and 1700 MHz to 2700 MHz.

15. A cavity filter comprising: a filter body; a resonator connected to the filter body and in contact with the filter body at a contact area to ground the resonator, said resonator including a bottom portion having a concentric ring stop limiter; and a compression plate positioned such that the stop limiter is located between the compression plate and the filter body to substantially eliminate movement of the resonator away from the contact area of the filter body.

16. The cavity filter as in claim 15, wherein the resonator comprises a deep drawn resonator.

17. The cavity filter as in claim 15, wherein the cavity filter is a part of a tower mounted amplifier or antenna.

18. The cavity filter as in claim 15, wherein the compression plate comprises a metallic material or a non-ferrous metallic material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 of the prior art depicts a cavity filter where a resonator is connected to a filter body using a known locked washer and screw configuration.

(2) FIG. 2 of the prior art depicts an expanded view of the filter in FIG. 1 including a grounding contact point.

(3) FIG. 3 depicts an expanded view of a cavity filter according to an embodiment of the present invention.

(4) FIG. 4 depicts a cavity filter where a resonator is connected to a filter body according to an embodiment of the present invention.

DETAILED DESCRIPTION, INCLUDING EXAMPLES

(5) Exemplary embodiments for grounding DDRs are described herein and are shown by way of example in the drawings. Throughout the following description and drawings, like reference numbers/characters refer to like elements.

(6) It should be understood that, although specific exemplary embodiments are discussed herein there is no intent to limit the scope of present invention to such embodiments. To the contrary, it should be understood that the exemplary embodiments discussed herein are for illustrative purposes, and that modified and alternative embodiments may be implemented without departing from the scope of the present invention. Further, though specific structural and functional details may be disclosed herein, these are merely representative for purposes of describing the exemplary embodiments.

(7) It should be noted that one or more exemplary embodiments may be described as a process or method. Although a process/method may be described as sequential, it should be understood that such a process/method may be performed in parallel, concurrently or simultaneously. In addition, the order of each step within a process/method may be re-arranged. A process/method may be terminated when completed, and may also include additional steps not included in a description of the process/method.

(8) As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. As used herein, the singular forms “a,” “an” and “the” are not intended to include the plural form, unless the context indicates otherwise.

(9) As used herein, the term “embodiment” refers to an embodiment of the present invention.

(10) FIG. 3 depicts an expanded, cross-sectional view of a cavity filter 40 according to an embodiment of the present invention. As shown the cavity filter 40 comprises a DDR 10 and filter body 20 that are connected using locked washer 30a, screw 30b and deflection reducing means 50a, 50b. In one embodiment of the invention, means 50a, 50b may comprise a compression plate 50a and a stop limiter 50b, respectively, positioned to substantially eliminate movement of the DDR 10 away from a contact area 20a of the filter body 20. Though not shown in FIG. 3, it should be understood that the opposite end of the DDR 10 may extend further and be connected to an amplifier or antenna, for example (connection not shown in figures). As shown, the compression plate 50a may cover the grounding contact area 20a. Further, while only “one” grounding contact area 20a appears to be shown in FIGS. 3 and 4, it should be understood that FIGS. 3 and 4 depict cross sectional areas of the components, and, therefore, in three dimensions, the contact area 20a area forms a circular contact area, for example, on the bottom surface 10b of the DDR 10.

(11) In the embodiment shown in FIG. 3 the combination of the plate 50a and limiter 50b substantially eliminates deflection of the bottom portion 10b which, in turn, substantially eliminates movement of the grounding contact point 20a. In more detail, the plate 50a functions to distribute the forces, being applied by the screw 30a and locked washer 30b, more evenly over the surface of the bottom portion 10b of DDR 10. This distribution has two effects. First, more of the force applied by the screw 30b and washer 30a is applied to the bottom portion 10b over area 20a via portion of plate 40a covering the area 20a. Second, less of the force is applied to an inner portion of the bottom portion 10b over area 20b. Both affects help minimize movement (e.g., deflection) of the DDR 1 away from the contact area 20a. By reducing or eliminating movement of the DDR 1 away from the contact area 20a the resonator 10 remains grounded to the filter body 20, which in turn substantially eliminates frequency drift.

(12) The compression plate may be made of a metallic material, such as a non-ferrous metallic material. Alternatively, the plate may be made from another suitable material. The plate may have a thickness that varies depending on the specific requirements of a particular cavity filter. In one embodiment the thickness may be 1 millimeter.

(13) It should be understood that though component 50a is described as a compression “plate” that other equivalent structure(s) may be substituted, provided, such structure functions to distribute some of force being supplied by a screw and washer, such as screw 30b and washer 30a, over the surface of a bottom portion of a DDR, such as DDR 10. In addition the plate may be substantially flat or may be conical in shape, for example.

(14) Further, though described as a stop limiter 50b, other equivalent structure(s) may be substituted, provided, such a structure functions to eliminate or substantially minimize over compression of the bottom portion of a DDR, such as DDR 10, which, in turn, eliminates or substantially minimizes the movement (e.g., deflection) of a DDR away from a grounding contact area. Still further, the “stepped” form of the limiter 50b depicted in FIG. 3 (and FIG. 4) is only one of many that may be encompassed by the scope of the present invention. For example, rather than be a stepped shape limiter the limiter may be configured as an embossed concentric ring. Yet still further, while the stop limiter 50b is depicted in FIGS. 3 and 4 as being formed from a portion of the bottom surface 10b of the DDR 10, it should be understood that the stop limiter may be a separate component inserted at least underneath the inner portion of the bottom portion 10b associated with area 20b.

(15) FIG. 4 depicts an enlarged, cross-sectional view of the cavity filter 40 depicted in FIG. 3 comprising the resonator 10 and filter body 20. In one embodiment of the invention, the resonator 10 may operate over a range of frequencies, including 698 MHz to 960 MHz, 1700 MHz to 2700 MHz, and other frequency ranges, and may be a part of a tower mounted amplifier, or antenna, such as a low band tower mounted amplifier to name just one of the many types of amplifiers and antennas covered by the present invention.

(16) While exemplary embodiments have been shown and described herein, it should be understood that variations of the disclosed embodiments may be made without departing from the spirit and scope of the claims that follow.