Transmission line resonator, band-pass filter and branching filter
AssigneeThe University of Electro-Communications
InventorsKoji Wada, Morikazu Sagawa, Mitsuo Makimoto
Life of this patent
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Abstract
A transmission line resonator includes distributed coupled lines including first distributed constant line which one ends are connected to a short-circuit grounding portion and second distributed constant line which is disposed in parallel to the first distributed constant line while being separated therefrom by a predetermined distance and which one ends opposing the short-circuit grounded one ends of the first distributed constant line are connected to the short-circuit grounding portion, and a single transmission line which both ends are connected to the respective other ends of the distributed coupled lines.
Claims11
A transmission line resonator, including:
- distributed coupled lines comprised of first distributed constant line which one ends are connected to a short-circuit grounding portion and second distributed constant line which is disposed in parallel to the first distributed constant line while being separated therefrom by a predetermined distance and which one ends opposing the short-circuit grounded one ends of the first distributed constant line are connected to the short-circuit grounding portion, and
- a single transmission line which both ends are connected to the respective other ends of the distributed coupled lines,
- wherein the distributed coupled lines have an even mode impedance and/or odd mode impedance, and wherein a resonance frequency of the transmission line resonator reduces in accordance with increases in a coupling coefficient of the distributed coupled lines which is given by an equation satisfying the following conditions:
- k=(Zce−Zco)/(Zce+Zco),0≦k≦1
- (where k is the coupling coefficient, Zce the even mode impedance and Zco the odd mode impedance.)
A band-pass filter, including two or more transmission line resonators of identical resonance frequency including distributed coupled lines comprised of first distributed constant line which one ends are connected to a short-circuit grounding portion and second distributed constant line which is disposed in parallel to the first distributed constant line while being separated therefrom by a predetermined distance and which one ends opposing the short-circuit grounded one ends of the first distributed constant line are connected to the short-circuit grounding portion, and a single transmission line both ends of which are connected to the respective other ends of the distributed coupled lines, wherein the single transmission line has a first line impedance and a first line length and is disposed in loop-like shape, wherein the distributed coupled lines have an even mode impedance and/or odd mode impedance and wherein a resonance frequency reduces in accordance with increases in coupling coefficients of the distributed coupled lines which are given by an equation satisfying the following conditions for resonating.
- k=(Zce−Zco)/(Zce+Zco),0≦k1≦1
- (where k is the coupling coefficient, Zce the even mode impedances and Zco the odd mode impedances.),
- having an input terminal that is coupled to one transmission line resonator from among the two or more transmission line resonators, and
- an output terminal that is coupled to another transmission line resonator from among the remaining one(s) of the two or more transmission line resonators,
- wherein the two or more transmission line resonators are coupled to adjoin each other while being separated from each other by a predetermined distance.
A multiplexer, including two or more band-pass filters obtained by coupling two or more transmission line resonators of identical resonance frequency to adjoin each other while being separated from each other by a predetermined distance, the two or more transmission line resonators including distributed coupled lines comprised of first distributed constant line which one ends are connected to a short-circuit grounding portion and second distributed constant line which is disposed in parallel to the first distributed constant line while being separated therefrom by a predetermined distance and which one ends opposing the short-circuit grounded one ends of the first distributed constant line are connected to the short-circuit grounding portion, and a single transmission line both ends of which are connected to the respective other ends of the distributed coupled lines, wherein the single transmission line has a first line impedance and a first line length and is disposed in loop-like shape, wherein the distributed coupled lines have an even mode impedance and/or odd mode impedance, and wherein a resonance frequency reduces in accordance with increases in coupling coefficients of the distributed coupled lines which are given by an equation satisfying the following conditions:
- k=(Zce−Zco)/(Zce+Zco),0≦k1≦1
- (where k is the coupling coefficient, Zce the even mode impedances and Zco the odd mode impedances.),
- having input terminals that are coupled to respective inputs of the two or more band-pass filters, and
- output terminals that are coupled to a transmission line resonator other than the transmission line resonators with the respective input terminals for the two or more band-pass filters, and
- wherein the two or more band-pass filters have respectively different passbands.
Dependencies are inferred from the claim text.