Wide bandwidth helical resonator filter
AssigneeMotorola, Inc.
InventorRonald J. Wanat
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Abstract
A helical resonator filter with increased bandwidth is provided for use as a wideband bandpass filter. The device is composed of a series of helical resonators cells cascaded with non-uniform cell spacing, thus providing an increase in coupling coefficients between cells. The increased bandwidth is thereby obtained without placing a burden on the exterior housing dimensions relative to a normally spaced narrow bandwidth filter and without substantially reducing the unloaded Q's or increasing insertion losses.
Claims4
A wideband helical resonator device for use in a circuit responsive to applied high frequency signals comprising:
- an elongated enclosure of conductive material;
- a least three helical coils each connected at one end to the inner surface of said enclosure, and arranged so as to have predetermined, and fixed, non-uniform spacing, and with the second end of each coil maintained in a fixed spatial relationship to said enclosure, whereby a pre-selected resonant frequency and a pre-selected bandwidth is obtained;
- means for input of high frequency signals;
- and
- means for output of high frequency signals.
The method of constructing a helical resonator bandpass filter which filter displays enhanced bandwidth and low insertion losses comprising the steps of:
- a. producing an elongated cavity composed of conductive material;
- b. connecting at least three helical coils at one end to the inner surface of said enclosure with predetermined and fixed, non-uniform spacing;
- c. mounting the second end of each coil in fixed spatial relationship to the walls of said enclosure;
- d. providing means for coupling high frequency signals into one end of said enclosure;
- and
- e. providing means to extract a high frequency signal from the other end of the enclosure.
Dependencies are inferred from the claim text.