Wave transmission lines and networks – Coupling networks – Wave filters including long line elements
Reexamination Certificate
1999-01-12
2001-07-03
Pascal, Robert (Department: 2817)
Wave transmission lines and networks
Coupling networks
Wave filters including long line elements
C333S206000, C333S219000, C333S222000, C333S230000, C029S527200, C029S600000
Reexamination Certificate
active
06255917
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
Not Applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed generally to a filter and, more particularly, to filters including capacitively coupled resonators and filters including resonators integral with a housing. The present invention is also directed to methods of making a filter.
2. Description of the Background
Filters utilizing stepped impedance resonators (SIRs) have been realized in various media, such as printed microstrip circuits, stripline, dielectric block, and air dielectric. Microstrip and stripline filters, however, often require the use of expensive substrate material and labor intensive assembly. Moreover, the electrical performance of such filters diminishes at lower frequencies, such as below about 400 MHz. Dielectric block resonators typically require the use of expensive dielectric material, which are additionally too heavy for certain applications. Furthermore, dielectric block resonators exhibit insertion loss, which is the loss of signal energy as the signal passes through the filter, which varies significantly based upon the type of dielectric used. Air dielectric combline filters use distributed capacitive coupling, which limits the bandwidth of the filter.
Accordingly, there exists a need for a filter that is small and light weight, and which maintains satisfactory electrical performance characteristics. Also, a need exists for such a filter which is operable at lower frequency ranges. In addition, there exists a need for a such a filter which allows for a wider range of bandwidths.
Brief Summary of the Invention
The present invention is directed to a filter including first and second resonators connected by a coaxial cable. The coaxial cable includes an inner conductor connected to the first resonator and an outer conductor connected to the second resonator.
The present invention is also directed to a filter including a housing and a plurality of stepped impedance resonators in which the high impedance portions of the stepped impedance resonators are integral with the housing. The stepped impedance resonators may be capacitively coupled, for example, by a coaxial cable or a trimmer capacitor. The present invention is also directed to a filter including a housing and a plurality of stepped impedance resonators in which the resonators are coupled by trimmer capacitors.
The present invention is also directed to a method of manufacturing a filter including forming a housing and a high impedance portion of a stepped impedance resonator as an integral piece, and fastening a low impedance portion of the resonator to the high impedance portion. The present invention is also directed to methods of coupling resonators.
The present invention solves problems experienced with the prior art because it is small, light weight, and operable at low frequencies. In addition, the present invention allows for a wider range of bandwidths. These and other advantages and benefits of the present invention will become apparent from the description of the embodiments hereinbelow.
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Sagawa et al., Geometrical Structures and Fundamental Characteristics of Microwave Stepped Impedance Resonators, IEEE Transactions on Microwave Theory and Techniques, v.45, No.7, Jul. 1997, pp. 1078-1085.
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Kirkpatrick & Lockhart LLP
Pascal Robert
Summons Barbara
Teledyne Technologies Incorporated
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