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:
Mar. 31, 1998
Filed:
Mar. 22, 1996
Kimmo Ervasti, Varjakka, FI;
LK-Products Oy, Kempele, FI;
Abstract
The invention relates to a resonator structure and radio frequency filter in which the resonating frequency of a transmission line resonator can be switched in a stepwise manner between at least three values. The switching is implemented as follows: a regulating element including a switch that has at least three states is arranged in connection with the resonator. The three states of the switch correspond to different values of the specific impedance and, hence, the resonating frequency of the transmission line resonator. The regulating element is in accordance with a known arrangement: it may be e.g. a coupling element formed of a strip line on the surface of a low-loss substrate or ceramic, or a side circuit including a capacitive and inductive element, coupled to the resonator. In the former example the switch is open in its first state, in its second state it grounds one end of the coupling element directly and in its other states it grounds the end of the coupling element through differently dimensioned transmission lines. In the latter implementation the switch is open in its first state, in its second state it forms at the side circuit a capacitive-inductive coupling in series and in its third state it bypasses the inductive element.