Alcatel Lucent

Radio Frequency Systems, Inc.

Michael Joseph Adkins

Yin-Shing Chong

Teppo M Lukkarila

Raja K Reddy

An embedded resonator sharpens the frequency characteristics of a coaxial low pass filter. The resonator introduces finite transmission zeros to the response of the low pass filter, thereby suppressing spurious modes occurring just above the operating frequency. Two parameters are used to tune the operation of the embedded resonator. The length of an insert into the filter's transmission line substantially controls the resonant frequency, and the gap width substantially controls the coupling of the embedded resonator to the low pass filter.

Low pass filter with embedded resonator

Various exemplary embodiments include a cavity having a tuning assembly with tunable capacitive coupling. The tuning assembly may have a recess having a specified depth, designed for a default magnitude of coupling into the cavity. A sleeve may be fully inserted within the recess to have the structure operate at that default coupling magnitude. If a different amount of coupling is desired, the sleeve may be inserted to a particular depth that only includes part of the recess, enabling repeatable tuning of a plurality of cavities.

Tunable capacitive input coupling

Various exemplary embodiments include a technique for tuning a filter to have two stop bands. This technique may involve combination of signals from a plurality of high-band notch resonators and low-band notch resonators. Loop wires may couple both high-band and low-band notch resonators to a central conductor, thereby enabling the central conductor to transmit a signal having dual stop bands.

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Fruitland, MD, United States of America

Michael Joseph Adkins