Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Distributive type parameters
Reexamination Certificate
1999-07-08
2001-12-11
Metjahic, Safet (Department: 2858)
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Distributive type parameters
C324S636000
Reexamination Certificate
active
06329824
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application is based upon and claims benefit of priority of Japanese Patent Application No. Hei-11-046877 filed on Feb. 24, 1999, the content of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of measuring a resonant frequency of a resonator, and more particularly to a method of measuring a resonant frequency of an individual resonator, a plurality of which constitute a filter.
2. Description of Related Art
A filter characteristic such as resonant frequency has to be adjusted after its manufacturing process is completed, because the characteristic usually deviates from its target due to various deviation factors such as dielectric constant of a substrate, thickness of layers, accuracy of a mask, manufacturing process conditions and the like. Such characteristic adjustment, or tuning is especially necessary for narrow band and low ripple filters.
Before or during such adjustment, it is necessary to accurately measure the resonant frequency of each resonator constituting a filter. Conventionally, a resonant frequency of each resonator is measured using a pair of probes attached to a resonator to be measured. Also, a coupling degree between two resonators selected arbitrarily among others is measured by the probes to check whether the coupling degree is realized as originally designed. However, the resonant frequency of an individual resonator and the coupling degree of two resonators cannot be accurately measured because of electromagnetic interference between the resonator to be measured and other neighboring resonators.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above-mentioned problem, and an object of the present invention is to provide an improved method, in which the resonant frequency of a resonator selected from among plural resonators is accurately and independently measured while eliminating interference from other resonators. Another object of the present invention is to provide a method of accurately measuring the coupling degree between two resonators without having electromagnetic interference from other resonators.
A distributed-constant-type filter is composed of a dielectric substrate, plural resonators formed on one surface of the substrate and a ground plane formed on the other surface of the substrate. The resonators may be patterned in a shape having two ends such as a ring having a small open gap, an elongate stripe, or the like. One resonator, the resonant frequency of which is to be measured, is arbitrarily selected from the plural resonators. The two ends of non-selected resonators are short-circuited with a conductive member which is easily removable to shift their resonant frequency to a frequency which does not interfere with the resonant frequency of the selected resonator. Then, the resonant frequency of the selected resonator is measured without electromagnetic interference from other resonators. Each resonator is selected one by one and its resonant frequency is accurately measured independently from other resonators. The resonators and the ground plane may be made of a superconductive material.
The resonant frequency of resonators constituting a lumped-constant-type filter is measured in the similar manner. In this case, non-selected resonators are covered with a conductive member to shift their resonant frequency. Non-selected resonators may be partially covered with the conductive member so that at least their capacitor and inductor portions are covered.
A coupling degree or coefficient of any one pair of resonators selected from the plural resonators can be measured under similar arrangement. Resonators other than a selected pair are short-circuited or covered with the conductive member to eliminate interference with the selected pair.
According to the present invention, the resonant frequency of one resonator is precisely measured, because interference from other resonators is eliminated by short-circuiting or covering other resonators with a conductive member. Also, the coupling degree of any pair of resonators is precisely measured in the same manner.
Other objects and features of the present invention will become more readily apparent from a better understanding of the preferred embodiments described below with reference to the following drawings.
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patent: 5227730 (1993-07-01), King et al.
patent: 5334941 (1994-08-01), King
Gerhard Sollner et al, “High-Power YBCO Microwave Filters and Their Nonlinearities”, 5thInternational Superconductive Electronics Conference (ISEC '95), Sep. 18-21, 1995, Nagoya, Japan, pp. 517-520.
Suzuki Masanobu
Tsuzuki Genichi
Advanced Mobile Telecommunications Technology Inc.
Hollington Jermele
Metjahic Safet
Nixon & Vanderhye P.C.
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