Wave transmission lines and networks – Plural channel systems – Having branched circuits
Reexamination Certificate
1999-05-24
2001-02-20
Lee, Benny (Department: 2817)
Wave transmission lines and networks
Plural channel systems
Having branched circuits
C333S135000, C333S033000, C333S239000, C333S253000, C333S209000
Reexamination Certificate
active
06191664
ABSTRACT:
BACKGROUND OF THE INVENTION
It is now prevalent in satellite microwave communications systems for the such systems to process multiple channels. This requires the combination or separation of the channels either for transmission or for processing after acquisition. This function is usually accomplished by means of a multiplexer. The typical multiplexer consists of a series of input waveguides generally including filter elements connected to a waveguide manifold through ports or irises. Each of the filters is tuned and the irises designed for maximum efficiency of the overall system.
In order to obtain optimum performance of the multiplexer, while minimizing losses, the internal impedance of the various components must be closely matched. This process of tuning the system requires the balancing of hundreds of variables many of which are extremely sensitive because of the high frequency environment. The design of these components has, therefore, become a difficult technological challenge. Although the optimization problem can be diminished through the use of various design techniques, because of the inherent limitations of manufacturing tolerances, the design of the these components ultimately relies on a trial and error process in which multiplexers are constructed, tested, modified, tested and gradually optimized in this manner. There are limits however, to the number of iterations which can be employed with constructive results.
It is a purpose of this invention to provide a multiplexer system and method of adjustment that allows a final adjustment of the impedance of the manifold to tune the overall system.
One means in the prior art for providing a final tuning step involves the insertion of tuning screws extending through the structure of the microwave filters, as shown in U.S. Pat. No. 4,614,920. A series of holes are drilled through the outer wall of the filter and screws are screwed in place to create adjustable perturbations on the inner surface of the associated filter waveguide cavity. This adjusting screw method, when applied to a tuning section as constructed in the manifold of this invention, creates undesirable reduction of power handling and contact problems leading to is possible generation of passive inter-modulation products (PIMS).
A waveguide system using a threaded rod protruding into a waveguide cavity for the purpose of fine tuning the impedance matching adjustment of the waveguide is shown in U.S. Pat. No. 4,200,847. This configuration also creates undesirable power handling and PIMS conditions.
It is a purpose of this invention to simulate the protrusions of the tuning screw without the need to fracture the wall of the waveguide and thereby avoid these problems.
SUMMARY OF THE INVENTION
The manifold of this invention is constructed with a primary manifold section to which the input wave guides, including filters, are connected and a tuning section attached to the output of the primary manifold section. The tuning section is constructed of a deformable material which allows the dimpling of the internal wall to alter the impedance of the waveguide system. The dimpling may be accomplished by an adjustable clamp or appropriate crimping tool which allows a controlled force to be exerted by the tool. The final adjustment is accomplished by monitoring the performance as dimples are constructed at various positions in the broad wall of the tuning section of the manifold.
REFERENCES:
patent: 2563612 (1951-08-01), Nebel
patent: 3974467 (1976-08-01), Tobita et al.
patent: 4200847 (1980-04-01), Nishikawa et al.
patent: 4614920 (1986-09-01), Tong
patent: 4780693 (1988-10-01), Elliott et al.
patent: 5977849 (1999-11-01), Hsing et al.
patent: 1015990 (1952-10-01), None
Dunker David J.
Fiedziuszko Slawomir J.
Lee Benny
Perman & Green LLP
Space Systems Loral, Inc.
Summons Barbara
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