Variable tuning device

Claim 2

A variable tuning device for selecting a signal of a desired frequency component from an input signal, comprising: a non-reversible circuit including a three-port circulator, having first, second and third ports respectively arranged in the direction of circulation of said circulator, wherein said input signal is applied at said first port, a signal corresponding to said input signal is provided from said first port to said second port; a resistive terminating element connected via a signal path to the second port; and a magnetic resonance element coupled with said signal path and having a variable resonance frequency, wherein the third port is supplied from the second port with said signal of a desired frequency component in correspondence to the resonance frequency of the resonance element.

Claim 3

A variable tuning device according to claim 1 which has cascade-connected thereto a variable tuning device of the same construction.

Claim 4

A variable tuning device according to claim 1 wherein the circulator is a variable bias type circulator having a variable working frequency depending on the magnitude of a bias magnetic field applied thereto.

Claim 5

The device of claim 3, wherein the resonance element is a magnetic resonance element, comprising means for varying simultaneously the resonance frequency thereof and the working frequency of the circulator.

Claim 6

A variable tuning device for selecting a signal of a desired frequency component from an input signal, comprising a non-reversible circuit having a first, second and third ports, wherein said input signal is applied at said first port, a signal corresponding to said input signal is provided from said first port to said second port, and the third port is supplied from the second port with said signal of a desired frequency component, a resistive terminating element connected via a signal path to the second port, and a resonance element electromagnetically coupled with said signal path and having a variable resonance frequency corresponding to said desired frequency component; wherein: the non-reversible circuit is a directional bridge in which two resistors are connected in common at respective first ends; the first port is led out from the common connection point of the two resistors; the second port is led out from the second end of a first one of the two resistors; a terminating resistor is connected to the second end of the second one of the two resistors; the primary side of a transformer is connected between the second ends of the two resistors; and the third port is led out from the secondary side of the transformer.

Claim 7

A variable tuning device for selecting a signal of a desired frequency component from an input signal, comprising a non-reversible circuit having a first, second and third ports, wherein said input signal is applied at said first port, a signal corresponding to said input signal is provided from said first port to said second port, and the third port is supplied from the second port with said signal of a desired frequency component, a resistive terminating element connected via a signal path to the second port, and a resonance element electromagnetically coupled with said signal path and having a variable resonance frequency corresponding to said desired frequency component; wherein: the non-reversible circuit is a directional bridge in which two resistors are connected in common at respective first ends; the first port is led out from the common connection point of the two resistors; the second port is led out from the second end of a first one of the two resistors; a terminating resistor is connected to the second end of the second one of the two resistors; the primary side of a transformer is connected between the second ends of the two resistors; and the third port is led out from the secondary side of the transformer.

Claim 8

A variable tuning device according to claim 5, wherein the resonance element is a parallel resonance circuit with a selectively variable resonance frequency and the parallel resonance circuit is electromagnetically coupled with the signal path.

Claim 9

A variable tuning device according to claim 5, wherein the resonance element is a series resonance circuit with a selectively variable resonance frequency and the series resonance circuit is connected in parallel with the resistive terminating element.

Claim 10

A variable tuning device according to claim 7 wherein the series resonance circuit is formed by a lumped constant element.

Claim 11

A variable tuning device according to claim 7 wherein the series resonance circuit is composed of a distributed constant element and a lumped constant element.

Claim 12

A variable tuning device for selecting a signal of a desired frequency component from an input signal, comprising: a non-reversible circuit having first, second and third ports, wherein said input signal is applied at said first port, a signal corresponding to said input signal is provided from said first port to said second port, and the third port is supplied from the second port with said signal of a desired frequency component, a resistive terminating element connected via a signal path to the second port; and a resonance element electromagnetically coupled with said signal path and having a variable resonance frequency corresponding to said desired frequency component; wherein the non-reversible circuit is a directional coupler with input, output and reflecting ports serving as the first, third and second ports, respectively.

Claim 13

A variable tuning device for selecting a signal of a desired frequency component from an input signal, comprising: a non-reversible circuit having first, second and third ports, wherein said input signal is applied at said first port, a signal corresponding to said input signal is provided from said first port to said second port, and the third port is supplied from the second port with said signal of a desired frequency component, a resistive terminating element connected via a signal path to the second port; and a resonance element electromagnetically coupled with said signal path and having a variable resonance frequency corresponding to said desired frequency component; wherein the non-reversible circuit is a directional coupler with input, output and reflecting ports serving as the first, third and second ports, respectively.

Claim 14

The device of claim 1, 5, 3 or 10, said resonance frequency being selectively variable by varying the strength of a magnetic field applied to said resonance element.