Wave transmission lines and networks – Resonators – Cavity resonator
Patent
1997-08-01
1998-12-15
Ham, Seungsook
Wave transmission lines and networks
Resonators
Cavity resonator
333235, H01P 706
Patent
active
058501690
DESCRIPTION:
BRIEF SUMMARY
This application is the national phase of international application PCT/FI96/00645 filed Dec. 3, 1996 which designated the U.S.
BACKGROUND OF THE INVENTION
The present invention relates to a device for filtering frequency, which device comprises a shell and a conductor adjustable in length, which conductor comprises an outer pipe affixed at its first end to the shell and an extruding adjusting element adjustable in the direction of the central axis of the outer pipe at the second, free end of the outer pipe by means of adjusting means for adjusting the length of the conductor, which adjusting element is of a flexible surface material and affixed at its first end to the outer pipe and at its other end to the adjusting means and which adjusting element forms the free end of the conductor.
For example, the filter according to Finnish Patent Application 944,806 comprises an outer pipe attached to the filter shell, adjusting means adapted coaxially inside the outer pipe and adjusting elements adapted between the outer pipe and the end of the adjusting means. When the axial distance of the adjusting means from the outer pipe changes, the frequency of the filter will change as well. The adjusting elements comprise a laminated or film structure bent and attached between the outer pipe and the end of the adjusting means.
The greatest problem with a solution of this type is that this method of adjusting frequency is inaccurate. A travel of one millimeter of the adjusting means corresponds to a frequency deviation of 2.6 MHz with a filter. This means that the frequency of the filter is very difficult to adjust manually to be correct. If a stepping motor moves the adjusting means, a great accuracy is required of the stepping motor in order that the filter will attain the desired frequency.
In the filter of the cited Finnish patent application, the laminated or film structure comprises several separate, adjoining lamellas or films essentially bent into a U shape and attached to one another into an annular structure and the laminated or film structure is attached to the outer pipe and the adjusting means with annular retainers whose periphery has mounting slots for said structure. The mounting of the adjusting element has thus been rather difficult and complicated.
Furthermore, the end of the adjusting film protruding from the outer pipe has not been in the same line as the outer pipe but the adjusting element has protruded essentially perpendicularly away from the line of the outer pipe. However, the object is that the length of the conductor, that is, the length in the direction of the free end of the outer pipe, can be adjusted. If the filter, for example, is also adjusted so that the part of the adjusting element bending most forms as small an angle as possible, such a great stress is directed to the adjusting element that in the worst case it may get damaged.
SUMMARY OF THE PRESENT INVENTION
The object of the present invention is to eliminate the disadvantages described above and improve the device.
The idea of the invention is that the second end of the adjusting element which is attached to the adjusting means is situated closer to the fixture of the outer pipe than the free end of the conductor. This structure provides the advantage that frequency adjustment will be considerably more accurate than in prior art solutions.
The solution of the invention will make the adjustment accuracy of frequency of the filter significantly better than in prior art solutions. In the solution of the invention, the frequency change of the filter corresponding to the travel of one millimeter of the adjusting means is only 1.6 MHz, whereas previously the frequency change has been as much as 2.6 MHz. The more accurate frequency adjustment of the invention is based on that the travel of the adjusting element will be half of that in the prior art solution. This essential improvement in frequency adjustment means that frequency can be easily adjusted just manually to be correct. If frequency adjustment is automatic, that is, a ste
REFERENCES:
patent: 2742617 (1956-04-01), Bondley
patent: 4207548 (1980-06-01), Graham et al.
patent: 4521754 (1985-06-01), Ranghelli et al.
patent: 5612655 (1997-03-01), Stronks et al.
Ham Seungsook
Nokia Telecommunications Oy
LandOfFree
Tunable cavity resonator for frequency filter does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Tunable cavity resonator for frequency filter, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Tunable cavity resonator for frequency filter will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1461204