The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 20, 2003
Filed:
Sep. 19, 2001
Erkki Niiranen, Ii, FI;
Tapani Vistbacka, Kempele, FI;
Filtronic LK Oy, Kempele, FI;
Abstract
The invention relates to a bandpass filter comprised of coaxial resonators. On the side of a resonator chain ( ) which makes the filter there is provided an additional equalizing resonator (EQ ) which is coupled to a resonator (R ) in the chain. The resonance frequency of the equalizing resonator and the coupling with the rest of the filter are arranged so that attenuation increases at a point corresponding to an original attenuation minimum. Thereby it follows that attenuation variation in the whole pass band decreases. Response equalization can be further enhanced by providing a second equalizer (EQ ) affecting a band beside the first one. Using the structure according to the invention, a decrease of a certain magnitude in the pass band attenuation variation of a bandpass filter can be achieved with a smaller increase in the number of resonators than in known structures. Moreover, the production costs caused by the additional structure are relatively small.