JPH0766610A - Ferromagnetic magnetic resonator - Google Patents

Abstract

PURPOSE:To control a resonance frequency by accurately obtaining synchronization at all times, to surely provide the fixed gap of the resonance frequency, to enable miniaturization, to reduce a cost and to provide a wide-band high- performance tuning system. CONSTITUTION:A main magnetic core part 21 is divided into a first main magnetic core part 21A and a second main magnetic core part 21B by a slit 29 provided along a magnetic flux direction and a coil 27 for sub excitation is wound around at least one of the main magnetic core parts. A first ferromagnetic resonance element 25A is arranged between the first main magnetic core part 21A and a sub magnetic core part 22 and a second ferromagnetic resonance element 25B is arranged between the second main magnetic core part 21B and the sub magnetic core part 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferromagnetic magnetic resonance apparatus, for example, a resonance apparatus suitable for a superheterodyne frequency conversion / tuning circuit.

[0002]

2. Description of the Related Art Conventionally, in a system for performing frequency conversion / tuning of a communication device or the like by a superheterodyne system,
As shown in FIG. 7, a resonance device in which a tuning / bandpass filter 1 and a local oscillator 2 are combined is known.

For example, for satellite broadcasting, the reception frequency of about 12 GHz received by the BS-antenna 3 is converted to the BS converter 4
Then, the frequency is converted to a first intermediate frequency of around 1 GHz, and this is supplied as an input (1stIFin) to the frequency conversion / tuning circuit 5 as a BS tuner.

In this frequency conversion / tuning circuit 5, 1st
The signal introduced from IFin is the tuning / bandpass filter 1
Removes harmful spurious signals and noise as it passes through
Only the signal in the necessary band (frequency is 1stIF) is added to the mixer 6 together with the signal oscillated by the local oscillator 2 (frequency is LO), and the second intermediate frequency signal (2n
dIF) and output.

Here, the tuning / bandpass filter 1 needs to change its center frequency in synchronization with the local oscillator 2 when performing tuning operation for tuning, and at the same time, the oscillation frequency of the local oscillator 2 is changed. And a constant intermediate frequency (I
A gap corresponding to the value of (F) (for example, LO
-1stIF = 2ndIF) is required.

The intermediate frequency IF must always be a constant frequency (normally 402.78 MHz) for the next detection and demodulation. For this reason, it is designed to perform frequency conversion accurately corresponding to the reception frequency, and in anticipation of future expansion of the reception frequency range, the tuning and bandpass filter 1 uses the 1stIF of 0.9 to 3.0 GHz (bandwidth 30 MHz). It is desired that the local oscillator 2 output LO of 1.3 to 3.4 GHz.

Therefore, different tuning / tuning is required for each selected channel.
The oscillation frequency LO of the local oscillator 2 is constantly adjusted to 400 MHz higher (or lower) with respect to the signal frequency 1stIF of the bandpass filter 1, and is changed in tune with the bandpass filter 1 so that there is no tuning error (tracking error). Will be required.

However, the tuning and
The band-pass filter 1 and the local oscillator 2 are each independently configured by an LC tuning element using a varactor, and frequency control is performed independently by varying the capacitance by the varactor. For this reason, the system becomes complicated, and it is unavoidable that a certain degree of synchronization error (tracking error) occurs due to variations in the characteristics of each tuning element.

As a countermeasure against this, the pass band width of the tuning / band filter 1 is made wider than necessary, but with this, C
/ N was an obstacle to improvement. Moreover, the entire apparatus becomes large, which is disadvantageous in terms of cost.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to always control the frequency with accurate synchronization, to ensure a constant frequency separation, and to reduce the size and cost. An object of the present invention is to provide a device capable of forming a high performance tuning system in a wide band.

[0011]

That is, the present invention provides a variable bias magnetic field applying means (for example, magnetic core portions 21 and 22 in which coils 20 and 27 described later are wound) and a magnetic circuit using the variable bias magnetic field applying means. A first ferromagnetic resonance element (for example, a ferromagnetic magnetic resonance body 25A described later) and a second ferromagnetic resonance element (for example, a ferromagnetic magnetic resonance body 25B described later) arranged inside
The variable bias magnetic field applying means has a main magnetic core portion (for example, an E-shaped core portion 21 for which the main excitation coil 20 described later) is wound, and the main magnetic core It is composed of a core portion and a sub magnetic core portion (for example, an I-shaped core portion 22 described later) that forms a magnetic circuit through a gap for a bias magnetic field (for example, a gap 23 described later). The first main magnetic core portion (for example, 21A described below) and the second main magnetic core portion (for example, 21
B) and a sub-excitation coil (for example, a sub-control coil 27 described later) is wound around at least one of the first main magnetic core portion and the second main magnetic core portion, The first ferromagnetic resonance element is disposed between the main magnetic core portion and the sub magnetic core portion, and the second ferromagnetic resonance element is disposed between the second main magnetic core portion and the sub magnetic core portion. The present invention relates to a ferromagnetic magnetic resonance device in which a ferromagnetic resonance element is arranged.

In the ferromagnetic magnetic resonance apparatus of the present invention, a tuning bias current is passed through the main excitation coil, and a common control magnetic field (for example, 24 which will be described later) generated thereby causes the first ferromagnetic resonance element and the above-mentioned ferromagnetic resonance element. Synchronous control of each resonance frequency with the second ferromagnetic resonance element is performed, and the auxiliary excitation coil corresponds to the difference in resonance frequency between the first ferromagnetic resonance element and the second ferromagnetic resonance element. Bias current to
The additional control field generated by this (eg 2
In 8), it is configured such that a constant difference (for example, a difference corresponding to the above-mentioned intermediate frequency IF) is generated between the resonance frequencies of the first ferromagnetic resonance element and the second ferromagnetic resonance element. Is desirable.

The ferromagnetic magnetic resonance apparatus of the present invention is suitable for, for example, the above-mentioned superheterodyne frequency conversion / tuning circuit for communication equipment for satellite broadcasting reception, and the first ferromagnetic resonance element is tuned. Function as a resonant element of a type bandpass filter (for example, tuning / bandpass filter unit 11 described later),
The second ferromagnetic resonance element can function as a resonance element of a local oscillator (for example, a local oscillator section 12 described later).

In this frequency conversion / tuning circuit, the resonance frequency of the second ferromagnetic resonance element (for example, L described later) is used.
It is desirable to detect O) and control the bias magnetic field based on the detected value.

The first ferromagnetic resonance element and the second ferromagnetic resonance element of the ferromagnetic magnetic resonance apparatus of the present invention are preferably composed of yttrium-iron-garnet (YIG) thin films. This YIG is, as will be described later,
The magnetic field of direct current causes a ferromagnetic resonance (ferrimagnetic resonance) having a remarkably high Q, and is suitable for the present invention as an electrical resonance element.

[0016]

EXAMPLES Examples of the present invention will be described below.

1 to 5 show an embodiment in which the present invention is applied to a frequency conversion / tuning circuit for a communication device such as a BS tuner.

First, referring to FIGS. 1 and 2, the structure of a ferromagnetic magnetic resonance apparatus 10 used in the present invention will be described. This device uses a ferrite E-shaped core portion 21 around which a main control coil (main excitation coil) 20 is wound, and a ferrite I-shaped core portion 22 joined to the core portion 21 to generate a bias magnetic field. The control magnetic circuit is formed through the gap 23.

A slit 29 is provided substantially in parallel with the main magnetic flux 24 at the central portion of the E-shaped core portion 21 as the main magnetic core portion.
As a result, the central portion is divided into two core portions 21A and 21B. Therefore, these core portions face the I-shaped core portion 22 as the sub magnetic core portion with a gap 23 therebetween.

And, each of these core portions 21A and 21B
Ferromagnetic magnetic resonators (YIG thin film) 25A and 25B are arranged in a magnetic field generated between the core portion 22 and the core portion 22, respectively. As will be described later in detail, these magnetic resonators are fixed on the sub core portion 22 while being held by the dielectric 26.

One of the magnetic resonators 25A is used as a resonance element of a tuning / bandpass filter section, and the other 25B is used as a resonance element of a local oscillator section. In this case, the sub-control coil (sub-excitation coil) 27 is wound only around the split core portion 21B facing the latter magnetic resonance body 25B, and the sub-magnetic flux 28 shown by the broken line is generated.

The structure of the resonant element portion including the ferromagnetic magnetic resonators 25A and 25B (disk-shaped YIG thin film) on the I-shaped core portion 22 is actually shown in an enlarged view in FIG. In the tuning / bandpass filter unit 11, the lower dielectric
A micro strip line 31-1 on the input (1stIFin) side and a micro strip line 32 on the output (1stIFout) side are formed on the upper surfaces of the disk-shaped YIG thin films 25A ₁ and 25A ₂ embedded in 26a. Another microstrip line 31-2 is provided between the dielectrics 26b-26c on the upper side, which are provided in parallel with each other and are orthogonal to the microstrip lines.

Further, in the local oscillator / resonator section 12, a disk-shaped YIG thin film 25B as a ferromagnetic magnetic resonator is provided in the dielectric 26a, and a micro strip line 33 is provided on the upper surface thereof. The frequency (L
It is adapted to be coupled to the active portion as a resonance element for oscillating the signal of O). Although the same applies to the tuning / bandpass filter section 11 described above, the ground layer 34 is commonly provided from the front surface to the bottom surface of the dielectric to form a microstrip line.

In the above-described resonant element section, the ferromagnetic magnetic resonators 25A and 25B can be formed by YIG thin film by liquid phase epitaxy technique, and the micro strip lines 31 and 32 are made of alumina or the like. Can be formed of a conductor such as gold provided on the dielectric substrate.

The operation of the ferromagnetic magnetic resonators 25A and 25B will be described here. As shown in FIG. 3, the DC magnetic field Ho
When the YIG single crystal 25 is placed inside, the magnetic moment M is Ho
In the direction of Ho, Mo is obtained while performing one kind of Serigotgi movement to align in the direction of. This is called precession. The angular frequency of precession is directly proportional to the magnitude of Ho. Also,
Magnetic field generated by RF signal (rotating magnetic field) so as to be orthogonal to Ho
When the frequency is added, it resonates with the precession motion only when its frequency matches the angular frequency of the precession motion, absorbs energy, and holds the precession motion. This is the principle of ferromagnetic magnetic resonance (ferrimagnetic resonance).

The resonance frequency fo due to this ferromagnetic magnetic resonance (ferrimagnetic resonance) is expressed by the following equation. fo = γ {Ho + (Nt-Nz) 4πMs + Ha} γ: Magneto-rotation ratio (2.8MHz / Oe) Nt: Transverse demagnetizing factor Nz: Vertical demagnetizing factor 4πMs: Saturation magnetization = Saturation magnetic flux density Ha: Anisotropy magnetic field

In the above equation, the term (Nt-Nz) is usually -1 (0 in a true sphere) in the YIG thin film, and the term Ha is usually negligible, so that the resonance frequency is approximately fo = γ (Ho. -4πMs). Therefore, it can be seen that the resonance frequency is directly proportional to the magnitude (Ho) of the DC magnetic field applied when YIG is magnetically saturated. The thin film of YIG has a lower resonance frequency than that of a true sphere, and is suitable for frequency conversion in this embodiment.

FIG. 3 shows the principle structure of a thin film YIG tuning filter, which is a GGG (gadolinium gallium garnet) substrate 26 provided on an alumina substrate 35.
The thin film YIG disk 25 arranged above is used as a resonator, and the microstrip line 3 is formed vertically above and below the resonator.
1, 32 are arranged. Each of these micro strip lines has an inlet (RFin) and an outlet (RFo).
However, there is no coupling between the micro strip lines 31-32 when the YIG disk 25 is not in resonance.

When a DC magnetic field Ho is applied to the YIG disk 25 in the vertical direction, ferrimagnetic resonance occurs,
High frequency signal (RFi from input strip line 31)
Only the signal corresponding to the resonance frequency of n) is absorbed by the YIG disk 25 and induced in the output strip line 32. This operation is basically the same as that of a conventionally known device using a spherical YIG single crystal.

Regarding the micro strip line, as is well known, a high frequency (microwave) signal input forms a standing wave having a maximum current value in the vicinity of its short end, and the high frequency magnetic field generated by this forms a YIG disk 25. To produce the above-mentioned resonance under the application of a DC magnetic field. As a result, the upper and lower micro strip lines are coupled, and the signal absorbed by the YIG disk 25 is induced as a high frequency output on the output side micro strip line in the vicinity of the short end. Such a mechanism is the basic principle of signal propagation between the micro strip lines shown in FIG.

As described above, the above-mentioned ferromagnetic magnetic resonance apparatus using the YIG disk continuously changes its center frequency when applied as a bandpass filter by changing the magnitude of the applied DC magnetic field. Can be made. This type of bandpass filter can be tuned over approximately 1 to 30 GHz, and various performances as a bandpass filter (attenuation in stop region = 60 dB or more) are very good. Therefore, by inserting this resonance system into the feedback section of the active element, a tunable oscillator can be obtained, and the local oscillator (local oscillator (local section) having a small phase noise and a high purity due to an extremely high Q is used. It has ideal characteristics as an oscillator.

Next, the operation of the above-mentioned ferromagnetic magnetic resonance apparatus 10 will be explained. When a control current flows through the main control coil 20, a magnetic flux 24 is generated, a direct current magnetic field is formed in the gap 23, and the magnetic resonance body 25A is produced. , 25B are simultaneously excited to excite magnetic resonance. Since the resonance frequency is proportional to the strength Ho of the DC magnetic field in the gap 23, the resonance frequency of the magnetic resonators 25A and 25B is changed and controlled in the same manner by changing the current of the main control coil 20. Become.

Further, when a constant direct current is applied to the sub control coil 27, a magnetic flux 28 is generated, which mainly affects the gap portion at the tip of one core portion 21B of the E-shaped core portion 21, and the main control coil 20 Will be added to the magnetic field. As a result, the DC magnetic field applied to the magnetic resonator 25B becomes larger than the DC magnetic field applied to the magnetic resonator 25A. If the current flowing through the sub control coil 27 is in the opposite direction, the DC magnetic field applied to the magnetic resonator 25B is smaller than the above.

In either case, the magnetic resonance
A constant difference is generated in the DC magnetic field applied to 25 A and a constant gap can be generated in each resonance frequency. In particular, if the resonance frequency of the magnetic resonance body 25A on the tuning / bandpass filter side is made to correspond to the above-mentioned 1stIF and the resonance frequency of the magnetic resonance body 25B at the local oscillator section side is made to correspond to the above-mentioned LO, this is Supply to mixer 6 | LO-1s
An intermediate frequency of tIF | = 2ndIF can always be obtained stably.

In this way, a tuning bias current is passed through the main control coil 20 and the resonance frequency difference (value of the intermediate frequency IF or the like) desired to be given to the sub control coil 27 between the two resonators is obtained. A ferromagnetic magnetic resonance device having two magnetic resonators 25A and 25B that can be tuned in synchronization while maintaining a constant distance by passing a constant direct current in a structure that can be regarded as almost the same structure. It can be used as a resonant device such as a frequency conversion / tuning system of a communication device.

Further, the adoption of a resonance device using a ferromagnetic magnetic resonance body composed of yttrium-iron-garnet (YIG) in such a system having a band exceeding 1 GHz makes it possible for a mixer to have a high selection performance. Since the spurious signal can be almost completely removed from the applied high frequency signal, an extremely wide band tuning system can be configured without considering the spurious signal, and a high performance system can be realized such as contributing to the improvement of C / N.

The ferromagnetic magnetic resonance apparatus 10 can be used in the same manner as described with reference to FIG. 7, but a frequency conversion / tuning circuit 35 for a communication device including its control circuit system will be described with reference to FIG.

In use as a BS tuner, for example, the tuning / bandpass filter unit 11 is supplied with the first intermediate frequency signal 1stIF (0.9 to 3 GHz) from the BS-converter, where spurious signals and noise are removed and required. It becomes the first intermediate frequency signal 1stIF of the band. Then, as described above, the tuning / bandpass filter unit 11 and the local oscillator / resonator unit 12 are tuned (synchronized) in correspondence with 1stIF, and the oscillation frequency LO of the local oscillator unit 12 is fixed between them. Resonance frequency difference (| LO-1stIF | = 2nd
IF), the synthesized tuning operation by the PLL is performed as follows.

That is, first, the oscillation frequency LO at that time from the local oscillator / resonator unit 12 is supplied to the frequency divider (Pre-Scaler) 36 as a comparison output, the frequency is once lowered, and then this is further reduced. Variable Divider (Programmable Divider)
Supply to 37, in contrast to this (1stIF + 2ndIF)
The frequency division ratio (commander) corresponding to is specified and input to the phase detector (Phase Detector) 38 at the next stage.

Then, the oscillation of the crystal oscillator 39 is made into a clock pulse of, for example, 10 MHz by the reference oscillator 40, and this is supplied to the phase detector 38, and when the LO frequency is changed and the phases match (that is, When LO matches the target LO), the output from the phase detector 38 becomes "0".

Until the phases match (ie the LO does not match the desired LO), the output from the phase detector 38 is fed through a low pass filter 41 to a DC amplifier 42, and thus in this case. From the DC amplifier 42, a tuning bias current is supplied to the coil 20 of the frequency conversion / tuning circuit 35, and at the same time, a DC bias current is continuously supplied to the sub-control coil 27. The magnetic flux described above together with the DC magnetic field due to the magnetic flux 24
A DC magnetic field generated by 28 is applied in synchronization with each of the ferromagnetic magnetic resonators 25A and 25B.

This means that if LO is low,
This means that the DC magnetic field is continuously applied to the magnetic resonator 25B of the local oscillator / resonator unit 12 until the desired LO is reached. When LO is high, the DC bias current is
It is reduced until the LO matches the LO sought.

Thus, the resonance (oscillation) of the local oscillator unit 12
The frequency is the signal frequency 1 from the tuning / band filter unit 11.
In synchronization with stIF, the LO (= 1stIF + 2ndIF) is controlled so that the difference from this is always 2ndIF.

FIG. 5 shows that the first intermediate frequency signal 1stIF from the tuning / bandpass filter unit 11 and the signal LO from the local oscillator / resonator unit 12 are supplied to the mixer 6, and the intermediate frequency 2
3 shows a circuit configuration for obtaining an output of ndIF. Here, it is possible to output as the local oscillation signal LO by coupling with the Colpitts type oscillator active section 43 by the micro strip line 33 of the local oscillator / resonator section 12.

The mixer 6 is configured as a two-gate FET, and when the above-mentioned first intermediate frequency signals 1stIF and LO are supplied to each gate, the square-law detection is performed by utilizing the non-linearity of the forward admittance of the FET. By doing so and obtaining the beat, the second intermediate frequency output 2ndIF is obtained.

FIG. 6 shows another embodiment of the present invention.

In the case of this example, as compared with the example of FIG.
The slit 29 formed on the core is enlarged, an additional coil 47 is wound around the core portion 21A, and a control bias current is also applied to this coil 47 to generate a third magnetic flux 46, which is generated on the tuning / bandpass filter side. A DC bias magnetic field is applied to the resonator 25A.

As a result, the resonance frequency of the band-pass filter can be arbitrarily controlled as compared with the example of FIG. 1, and various frequencies can be obtained according to the purpose.

Although the embodiments of the present invention have been described above, the above-described embodiments can be further modified based on the technical idea of the present invention.

For example, the position, shape, size, number (division number of the central portion of the core portion 21) and the like of the slits 29 formed in the above-mentioned main magnetic core portion 21 may be variously changed, and according to this, The position of the sub-control coil 27 that controls the resonator 25B,
You may change the number of turns. The number of ferromagnetic magnetic resonators is not limited to that described above.

Further, the material and the forming method of the constituent parts of the above-mentioned device may be changed, and in particular, the ferromagnetic magnetic resonator is YIG.
It can be used in other than.

Also, the frequency to be received is not limited to the above-mentioned frequency, and the above-mentioned device is useful as an oscillating element for a communication device in another band or for other purposes. In the above example, the receiving system has been described, but it is effective to use the same device as described above also for the transmitting system, although the characteristics of spurious to be removed are different.

[0053]

As described above, the present invention divides the main magnetic core portion into the first main magnetic core portion and the second main magnetic core portion by the notches provided along the magnetic flux direction. A sub-excitation coil is wound around at least one of the two main magnetic core portions, the first ferromagnetic resonance element is arranged between the first main magnetic core portion and the sub magnetic core portion, and the second main magnetic core element is provided. Since the second ferromagnetic resonance element is arranged between the magnetic core portion and the sub magnetic core portion, a tuning bias current is passed through the main excitation coil of the main magnetic core portion, and the sub excitation coil is also provided. A plurality of magnetic resonances that can be tuned in synchronism while maintaining a constant gap by flowing a constant DC current corresponding to the difference in resonance frequency (value of intermediate frequency IF, etc.) to be applied between the two resonance elements. I had the body in a structure that can be regarded as almost the same structure It can be a magnetic magnetic resonance apparatus.

Therefore, it can be used as a resonance device such as a frequency conversion / tuning system of a communication device, which has the following remarkable effects (1) to (4).

(1) Since the resonance frequency can be controlled (tuned) by the common control magnetic field, no synchronization error occurs. (2) By passing a constant current through the sub-excitation coil wound in the minor loop of the control magnetic circuit, it is possible to set an arbitrary resonance frequency separation between the resonance elements. (3) Since it is controlled by a magnetic circuit that can be regarded as a single common unit, a compact and low-priced structure can be achieved. (4) Since the resonance device uses ferromagnetic magnetic resonance such as yttrium, iron, garnet (YIG), etc., spurious signals can be almost completely removed from the input signal by advanced selection performance, and spurious signals can be eliminated. , A very wide band tuning system can be constructed, and it can contribute to the improvement of C / N, so that a high performance system can be realized.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a ferromagnetic magnetic resonance apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged plan view of a resonance element portion of the device and its X-
It is an X-ray sectional view.

FIG. 3 is a schematic perspective view for explaining the operating principle of the resonance element section of the device.

FIG. 4 is a block diagram showing a frequency conversion / tuning circuit and its control system using the same device.

FIG. 5 is an equivalent circuit diagram of the frequency conversion / tuning circuit.

FIG. 6 is a schematic view of a ferromagnetic magnetic resonance apparatus according to another embodiment of the present invention.

FIG. 7 is a schematic block diagram for explaining a frequency conversion / tuning circuit.

[Explanation of symbols]

1, 11 ... Tuning / band filter (part) 2 ... Local oscillator 5, 35 ... Frequency conversion / tuning circuit 6 ... Mixer 10 ... Ferromagnetic resonance device 12 ... Local oscillator・ Resonator part 20 ・ ・ ・ Main control coils 21, 22 ・ ・ ・ Core part 21A, 21B ・ ・ ・ Core part 23 ・ ・ ・ Gap 24 ・ ・ ・ Main magnetic flux 25A, 25A ₁ , 25A ₂ , 25B ・ ・ ・Ferromagnetic magnetic resonance 26 ... Dielectric 27 ... Sub control coil 28 ... Sub magnetic flux 29 ... Slits 31, 31-1, 31-2, 32, 33 ... Micro strip line 34 ... Ground layer 1stIFin ... First intermediate frequency input signal 1stIFout ... First intermediate frequency output signal 1stIF ... First intermediate frequency LO ... Local oscillation frequency 2ndIF ... Second intermediate frequency

Claims (5)

[Claims] 1. A variable bias magnetic field applying means, and a first ferromagnetic resonance element and a second ferromagnetic resonance element arranged in a magnetic circuit by the variable bias magnetic field applying means, wherein the variable bias magnetic field is provided. The applying means includes a main magnetic core portion around which a main excitation coil is wound, and a sub magnetic core portion that forms a magnetic circuit together with the main magnetic core portion through a gap for a bias magnetic field, and the main magnetic core portion is , A first main magnetic core portion and a second main magnetic core portion are divided by a notch provided along the magnetic flux direction, and the first main magnetic core portion and the second main magnetic core portion are divided into A sub-excitation coil is wound around at least one side, the first ferromagnetic resonance element is arranged between the first main magnetic core portion and the sub magnetic core portion, and the second magnetic resonance element is provided.
Between the main magnetic core portion and the sub magnetic core portion of
Ferromagnetic resonance device in which the ferromagnetic resonance element of is arranged. 2. A main biasing coil is supplied with a tuning bias current, and a common control magnetic field generated thereby performs synchronous control of resonance frequencies of the first ferromagnetic resonance element and the second ferromagnetic resonance element. A bias current corresponding to the difference in resonance frequency between the first ferromagnetic resonance element and the second ferromagnetic resonance element is passed through the sub-excitation coil, and the additional control magnetic field generated by the bias current causes the bias current to flow. The ferromagnetic magnetic resonance apparatus according to claim 1, wherein a constant difference is generated between respective resonance frequencies of the first ferromagnetic resonance element and the second ferromagnetic resonance element. 3. A superheterodyne frequency conversion / tuning circuit, wherein the first ferromagnetic resonance element functions as a resonance element of a tunable bandpass filter, and the second ferromagnetic resonance element is a resonance element of a local oscillator. The ferromagnetic magnetic resonance apparatus according to claim 2, which functions as: 4. The ferromagnetic magnetic resonance apparatus according to claim 3, wherein the resonance frequency of the second ferromagnetic resonance element is detected, and the bias magnetic field is controlled based on the detected value. 5. The ferromagnetic magnet according to claim 1, wherein the first ferromagnetic resonance element and the second ferromagnetic resonance element are made of yttrium / iron / garnet thin films. Resonance device.