CN111033889A - Directional coupler and microwave heating device with same - Google Patents
Directional coupler and microwave heating device with same Download PDFInfo
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- CN111033889A CN111033889A CN201980003790.XA CN201980003790A CN111033889A CN 111033889 A CN111033889 A CN 111033889A CN 201980003790 A CN201980003790 A CN 201980003790A CN 111033889 A CN111033889 A CN 111033889A
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- 238000010438 heat treatment Methods 0.000 title claims description 27
- 230000005540 biological transmission Effects 0.000 claims abstract description 100
- 230000008878 coupling Effects 0.000 claims abstract description 87
- 238000010168 coupling process Methods 0.000 claims abstract description 87
- 238000005859 coupling reaction Methods 0.000 claims abstract description 87
- 230000001902 propagating effect Effects 0.000 claims description 29
- 239000007787 solid Substances 0.000 description 48
- 239000000758 substrate Substances 0.000 description 14
- 238000001514 detection method Methods 0.000 description 13
- 238000010586 diagram Methods 0.000 description 8
- 230000004048 modification Effects 0.000 description 7
- 238000012986 modification Methods 0.000 description 7
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 4
- 230000008859 change Effects 0.000 description 4
- 239000011889 copper foil Substances 0.000 description 4
- 230000005684 electric field Effects 0.000 description 4
- 230000005855 radiation Effects 0.000 description 4
- 238000000926 separation method Methods 0.000 description 3
- 230000010287 polarization Effects 0.000 description 2
- 230000000644 propagated effect Effects 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000001154 acute effect Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000009499 grossing Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P5/00—Coupling devices of the waveguide type
- H01P5/08—Coupling devices of the waveguide type for linking dissimilar lines or devices
- H01P5/10—Coupling devices of the waveguide type for linking dissimilar lines or devices for coupling balanced lines or devices with unbalanced lines or devices
- H01P5/107—Hollow-waveguide/strip-line transitions
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P5/00—Coupling devices of the waveguide type
- H01P5/12—Coupling devices having more than two ports
- H01P5/16—Conjugate devices, i.e. devices having at least one port decoupled from one other port
- H01P5/18—Conjugate devices, i.e. devices having at least one port decoupled from one other port consisting of two coupled guides, e.g. directional couplers
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/64—Heating using microwaves
- H05B6/70—Feed lines
- H05B6/707—Feed lines using waveguides
- H05B6/708—Feed lines using waveguides in particular slotted waveguides
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- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Waveguide Aerials (AREA)
- Constitution Of High-Frequency Heating (AREA)
- Waveguide Switches, Polarizers, And Phase Shifters (AREA)
Abstract
The directional coupler has an opening and a coupling line. The opening has a1 st long hole and a 2 nd long hole which are arranged at positions which do not intersect with the tube axis of the waveguide in a plan view and intersect with each other. The coupling line has a1 st transmission line and a 2 nd transmission line. The 1 st transmission line has a1 st crossover portion. The 1 st intersecting line portion extends so as to be separated from the tube axis as approaching from one end of the tube axis to a perpendicular line perpendicular to the tube axis through an opening intersecting portion where the 1 st long hole and the 2 nd long hole intersect, and intersects the 1 st long hole at a position separated from the tube axis than the opening intersecting portion. The 2 nd transmission line has a 2 nd crossover portion. The 2 nd intersecting line portion extends so as to be separated from the tube axis as approaching the perpendicular line from the other end of the tube axis in a plan view, and intersects the 2 nd long hole at a position separated from the tube axis than the opening intersecting portion. The 1 st transmission line and the 2 nd transmission line are connected to each other at positions deviated from the region of the opening in a plan view.
Description
Technical Field
The present disclosure relates to a directional coupler that detects a power level of a microwave propagating in a waveguide and a microwave heating apparatus having the directional coupler.
Background
A directional coupler is known as a device for detecting the power level of a microwave propagating through a waveguide. The directional coupler separates the traveling wave and the reflected wave propagating in the waveguide and detects them separately.
As a conventional directional coupler, for example, a directional coupler described in patent document 1 is known. The directional coupler of patent document 1 includes an opening portion disposed on a wall surface of a waveguide and a coupling line disposed outside the waveguide. The opening is disposed at a position not intersecting with the tube axis of the waveguide in a plan view, and is formed to radiate circularly polarized microwaves. The coupling line has a1 st transmission line and a 2 nd transmission line that cross the opening in a plan view. The 1 st transmission line and the 2 nd transmission line are disposed so as to face each other with the center of the opening interposed therebetween, and are connected to each other at a position offset from a region vertically above the opening.
According to the directional coupler of patent document 1, the rotation direction of the circularly polarized traveling wave radiated from the opening is opposite to the rotation direction of the circularly polarized reflected wave. By utilizing the difference in the rotation direction of the circularly polarized microwaves, the forward wave and the reflected wave can be separated and detected separately.
Documents of the prior art
Patent document
Patent document 1: japanese patent No. 6176540
Disclosure of Invention
However, in the conventional directional coupler, there is still room for improvement in terms of separating and detecting the forward wave and the reflected wave with higher accuracy.
Accordingly, an object of the present disclosure is to provide a directional coupler capable of separating and detecting a traveling wave and a reflected wave with higher accuracy, and a microwave heating apparatus having the same.
A directional coupler according to one aspect of the present disclosure includes an opening portion disposed on a wall surface of a waveguide and a coupling line disposed outside the waveguide, and separates and detects a traveling wave and a reflected wave propagating through the waveguide.
The opening has a1 st long hole and a 2 nd long hole which are arranged at positions which do not intersect with the tube axis of the waveguide in a plan view and intersect with each other. The coupling line has a1 st transmission line and a 2 nd transmission line.
The 1 st transmission line has a1 st crossover portion. The 1 st intersecting line portion extends so as to be separated from the tube axis as approaching from one end of the tube axis to a perpendicular line perpendicular to the tube axis through an opening intersecting portion where the 1 st long hole and the 2 nd long hole intersect, and intersects the 1 st long hole at a position separated from the tube axis than the opening intersecting portion.
The 2 nd transmission line has a 2 nd crossover portion. The 2 nd intersecting line portion extends so as to be separated from the tube axis as approaching the perpendicular line from the other end of the tube axis in a plan view, and intersects the 2 nd long hole at a position separated from the tube axis than the opening intersecting portion.
One end of the 1 st transmission line is connected to one end of the 2 nd transmission line at a position deviated from the region of the opening in plan view.
According to the directional coupler of the present embodiment, the forward wave and the reflected wave can be separated and detected with higher accuracy.
Drawings
Fig. 1 is a perspective view of a directional coupler according to an embodiment of the present disclosure.
Fig. 2 is a perspective view of the directional coupler according to the embodiment with the printed board removed.
Fig. 3 is a plan view of the waveguide of the embodiment.
Fig. 4 is a circuit configuration diagram of a printed board provided on the directional coupler of the embodiment.
Fig. 5 is a diagram for explaining the principle of emitting circularly polarized microwaves from the cross apertures.
Fig. 6 is a diagram for explaining the direction and amount of a microwave that propagates through a microstrip line and changes with time.
Fig. 7 is a diagram for explaining the direction and amount of microwaves that propagate through the microstrip line and change with time.
Fig. 8A is a plan view showing a1 st modification of the microstrip line.
Fig. 8B is a plan view showing a 2 nd modification of the microstrip line.
Fig. 8C is a plan view showing a 3 rd modification of the microstrip line.
Fig. 8D is a plan view showing a 4 th modification of the microstrip line.
Fig. 8E is a plan view showing a 5 th modification of the microstrip line.
Fig. 8F is a plan view showing a 6 th modification of the microstrip line.
Fig. 9 is a schematic view of a microwave heating apparatus according to an embodiment.
Detailed Description
The present inventors have conducted intensive studies to separate and detect a forward wave and a reflected wave with higher accuracy, and as a result, have obtained the following findings.
In the conventional directional coupler, the coupling line is formed by connecting a plurality of lines parallel to the tube axis in a plan view and a plurality of lines perpendicular to the tube axis in a plan view at right angles to each other into one line. According to this configuration, the influence of the impedance of the load connected to the waveguide can be alleviated, and the forward wave and the reflected wave can be separated with high accuracy.
The present inventors have found that, at a portion where the coupling line is bent at a right angle (or an acute angle), a magnetic field is concentrated, and the flow of current (microwaves) in the coupling line is blocked, thereby affecting the degree of separation between the forward wave and the reflected wave. The present inventors have found that in a conventional directional coupler, there are many places where the coupling line is bent at right angles, and that these have a large influence on the degree of separation between the forward wave and the reflected wave. The present inventors have found that the current flow in the coupling line can be suppressed from being hindered by separating the bent portion of the coupling line from the region in the vertical direction of the opening that is strongly influenced by the magnetic field.
Based on these findings, the present inventors have found the following invention. The present inventors have confirmed that, according to these inventions, directivity (the degree of separation between a forward wave and a reflected wave) is improved by 5dB or more (about 3 times or more) as compared with a conventional directional coupler.
A directional coupler according to claim 1 of the present disclosure includes an opening portion disposed on a wall surface of a waveguide and a coupling line disposed outside the waveguide, and separates and detects a traveling wave and a reflected wave propagating through the waveguide.
The opening has a1 st long hole and a 2 nd long hole which are arranged at positions which do not intersect with the tube axis of the waveguide in a plan view and intersect with each other. The coupling line has a1 st transmission line and a 2 nd transmission line.
The 1 st transmission line has a1 st crossover portion. The 1 st intersecting line portion extends so as to be separated from the tube axis as approaching from one end of the tube axis to a perpendicular line perpendicular to the tube axis through an opening intersecting portion where the 1 st long hole and the 2 nd long hole intersect, and intersects the 1 st long hole at a position separated from the tube axis than the opening intersecting portion.
The 2 nd transmission line has a 2 nd crossover portion. The 2 nd intersecting line portion extends so as to be separated from the tube axis as approaching the perpendicular line from the other end of the tube axis in a plan view, and intersects the 2 nd long hole at a position separated from the tube axis than the opening intersecting portion.
One end of the 1 st transmission line is connected to one end of the 2 nd transmission line at a position deviated from the region of the opening in plan view.
In the directional coupler of the 2 nd aspect of the present disclosure, in the 1 st aspect, the 1 st transmission line and the 2 nd transmission line are connected to each other at the following positions: the position is outside a rectangular region circumscribed with the opening in a plan view and is further away from the pipe axis than the rectangular region.
In the directional coupler according to claim 3 of the present disclosure, in addition to the 1 st aspect, at least one of the 1 st cross line portion and the 2 nd cross line portion intersects the corresponding 1 st long hole or the 2 nd long hole at a position closer to the opening end portion than the opening cross portion in a plan view.
In the directional coupler according to claim 4 of the present disclosure, in addition to the 1 st aspect, at least one of the 1 st cross line portion and the 2 nd cross line portion is perpendicular to the corresponding 1 st long hole or 2 nd long hole in a plan view.
In the directional coupler according to claim 5 of the present disclosure, in addition to the 1 st aspect, the coupling line includes a plurality of straight line portions including a1 st crossover portion and a 2 nd crossover portion. Two of the plurality of straight portions adjacent to each other are connected so as to form an obtuse angle.
In the directional coupler according to claim 6 of the present disclosure, in addition to the 5 th aspect, the plurality of linear portions include a linear portion connecting the other end of the 1 st cross line portion and the 1 st output portion, and a linear portion connecting the 2 nd cross line portion and the 2 nd output portion.
In the directional coupler according to claim 7 of the present disclosure, in addition to the 1 st aspect, 1/4 in which the total distance of the 1 st transmission line and the 2 nd transmission line, which are farther from the tube axis than the virtual straight line passing through the 1 st coupling point, which is the intersection of the 1 st crossline portion and the 1 st long hole, and the 2 nd coupling point, which is the intersection of the 2 nd crossline portion and the 2 nd long hole, in a plan view, is set to be the effective length is set.
In the directional coupler according to claim 8 of the present disclosure, in addition to the 1 st aspect, 1/2, which is an effective length, is set to be a total distance of the 1 st transmission line and the 2 nd transmission line that are farther from the tube axis than a parallel line that passes through the opening intersection and is parallel to the tube axis in a plan view.
A microwave heating device according to claim 9 of the present disclosure includes the directional coupler according to claim 1.
Hereinafter, a directional coupler according to an embodiment of the present disclosure and a microwave heating apparatus having the same will be described with reference to the drawings.
Fig. 1 is a perspective view of a directional coupler 5 of an embodiment of the present disclosure. Fig. 2 is a perspective view of the directional coupler 5 with the printed substrate 12 removed. Fig. 3 is a plan view of the waveguide 3. Fig. 4 is a circuit configuration diagram of the printed substrate 12 provided on the directional coupler 5.
As shown in fig. 1 to 3, the directional coupler 5 is disposed on a wall surface of the waveguide 3 that transmits microwaves. The waveguide 3 is a square waveguide. The cross section of the waveguide 3 perpendicular to the tube axis L1 has a rectangular shape. The tube axis L1 is the central axis of the waveguide 3 in the width direction.
The directional coupler 5 has a cross opening 11, a printed substrate 12, and a support portion 14. The intersection opening 11 is an X-shaped opening disposed in the Wide Plane (Wide Plane)3a of the waveguide 3. The printed board 12 is disposed outside the waveguide 3 so as to face the intersection opening 11. The support portion 14 supports the printed substrate 12 on the outer surface of the waveguide 3.
As shown in fig. 3, the intersection opening 11 is disposed at a position not intersecting the tube axis L1 of the waveguide 3 in a plan view. The opening center portion 11c of the cross opening 11 is disposed apart from the tube axis L1 of the waveguide 3 by a dimension D1 in a plan view. Dimension D1 is, for example, 1/4 of the width of waveguide 3. The cross opening 11 emits the microwave propagating through the waveguide 3 as a circularly polarized microwave toward the printed circuit board 12.
The opening shape of the intersection opening 11 is determined according to conditions such as the width and height of the waveguide 3, the power level and frequency band of the microwave propagating through the waveguide 3, and the power level of the circularly polarized microwave emitted from the intersection opening 11.
For example, when the width of the waveguide 3 is 100mm, the height is 30mm, the thickness of the wall surface of the waveguide 3 is 0.6mm, the maximum power level of the microwave propagating in the waveguide 3 is 1000W, the frequency band is 2450MHz, and the maximum power level of the circularly polarized microwave radiated from the intersection 11 is about 10mW, the length 11W and the width 11d of the intersection 11 are set to 20mm and 2mm, respectively.
As shown in fig. 4, the cross opening 11 includes a1 st long hole 11e and a 2 nd long hole 11f that cross each other. The opening center portion 11c of the intersecting opening 11 coincides with an opening intersecting portion where the 1 st long hole 11e and the 2 nd long hole 11f intersect. Intersection opening 11 is formed line-symmetrically with respect to perpendicular line L2. Perpendicular line L2 is perpendicular to tube axis L1 and passes through opening center portion 11 c.
In the present embodiment, the 1 st long hole 11e and the 2 nd long hole 11f intersect at an angle of 90 degrees. However, the present disclosure is not limited thereto. The 1 st long hole 11e and the 2 nd long hole 11f may intersect at an angle of 60 degrees or 120 degrees.
When the opening center portion 11c of the cross opening 11 is disposed at a position overlapping the pipe axis L1 in a plan view, the electric field reciprocates in the microwave transmission direction without rotating. In this case, the cross aperture 11 radiates a polarized microwave.
If the opening center portion 11c is slightly deviated from the tube axis L1, the electric field rotates. However, when the opening center portion 11c approaches the tube axis L1 (the closer to 0mm the dimension D1), an irregular rotating electric field is generated. In this case, the cross opening 11 radiates elliptically polarized microwaves.
In the present embodiment, the dimension D1 is set to about 1/4 of the width of the waveguide 3. In this case, a substantially standard circular rotating electric field is generated. The cross hatch 11 emits a substantially standard circular circularly polarized microwave. Therefore, the rotation direction of the circularly polarized microwave becomes more definite. As a result, the forward wave and the reflected wave can be separated and detected with high accuracy.
The printed board 12 has a board back surface 12b facing the intersection opening 11 and a board front surface 12a on the opposite side of the board back surface 12 b. The substrate front surface 12a has a copper foil (not shown) as an example of the microwave reflecting member, which is formed so as to cover the entire substrate front surface 12 a. The copper foil prevents the circularly polarized microwaves emitted from the intersection opening 11 from transmitting through the printed circuit board 12.
As shown in fig. 4, a microstrip line 13 as an example of a coupling line is disposed on the substrate back surface 12 b. The microstrip line 13 is constituted by a transmission line having a characteristic impedance of about 50 Ω, for example. The microstrip line 13 is arranged so as to surround the opening center portion 11c of the intersection opening 11.
Hereinafter, the effective length λ of the microstrip line 13reThe description is given. Assuming that the width of the microstrip line 13 is w, the thickness of the printed board 12 is h, the speed of light is c, the frequency of the electromagnetic wave is f, and the relative dielectric constant of the printed board is epsilonrThe effective length λ of the microstrip line 13reRepresented by the following formula. Effective length λreRefers to the wavelength of the electromagnetic wave propagating in the microstrip line 13.
[ formula 1]
Specifically, the microstrip line 13 has a1 st transmission line 13a and a 2 nd transmission line 13 b. The 1 st transmission line 13a includes a1 st straight line portion 13aa as an example of a1 st crossover portion. The 1 st linear portion 13aa intersects the 1 st elongated hole 11e at a position farther from the tube axis L1 than the opening center portion 11c in plan view. The 1 st linear portion 13aa extends away from the tube axis L1 as approaching the perpendicular line L2.
The 2 nd transmission line 13b has a 2 nd straight line portion 13ba as an example of the 2 nd intersecting line portion. The 2 nd linear portion 13ba intersects the 2 nd elongated hole 11f at a position farther from the tube axis L1 than the opening center portion 11c in plan view. The 2 nd linear portion 13ba extends away from the tube axis L1 as approaching the perpendicular line L2. First linear portion 1 aa and second linear portion 2 ba 13 are arranged line-symmetrically with respect to perpendicular line L2.
The 1 st transmission line 13a and the 2 nd transmission line 13b are connected to each other at the following positions: this position is outside the rectangular region E1 in plan view and is farther from the tube axis L1 than the rectangular region E1. The 1 st linear portion 13aa intersects the 1 st long hole 11e at a position closer to the opening distal end portion 11ea than the opening central portion 11c in a plan view.
The 1 st linear portion 13aa is perpendicular to the 1 st elongated hole 11e in a plan view. The 2 nd straight portion 13ba intersects the 2 nd long hole 11f at a position closer to the opening distal end portion 11fa than the opening center portion 11c in a plan view. The 2 nd linear portion 13ba is perpendicular to the 2 nd elongated hole 11f in a plan view.
One end of the 1 st transmission line 13a and one end of the 2 nd transmission line 13b are connected to each other outside the region overlapping the intersection 11 in a plan view. One end of the 1 st linear portion 13aa is connected to one end of the 2 nd linear portion 13ba outside the rectangular region E1 circumscribed with the cross opening 11.
The 1 st coupling point P1 is a point at which the 1 st linear portion 13aa and the 1 st elongated hole 11e intersect with each other in plan view. The 2 nd coupling point P2 is a point at which the 2 nd linear portion 13ba and the 2 nd elongated hole 11f intersect with each other in a plan view. A straight line connecting the 1 st coupling point P1 and the 2 nd coupling point P2 is defined as a virtual straight line L3. In the present embodiment, the total distance of the 1 st transmission line 13a and the 2 nd transmission line 13b, which are farther from the pipe axis L1 than the virtual straight line L3, is set to the effective length λ re1/4 of (1).
A line passing through the opening center portion 11c and parallel to the tube axis L1 in plan view is a parallel line L4. In the present embodiment, the total distance of the 1 st transmission line 13a and the 2 nd transmission line 13b, which are farther from the pipe axis L1 than the parallel line L4, is set to the effective length λ re1/2 of (1).
The 1 st transmission line 13a has a 3 rd linear part 13ab connecting the other end of the 1 st linear part 13aa and the 1 st output part 131. The 1 st linear part 13aa and the 3 rd linear part 13ab are connected to form an obtuse angle (e.g., 135 degrees).
The 2 nd transfer line 13b has a 4 th straight line portion 13bb connecting the other end of the 2 nd straight line portion 13ba with the 2 nd output portion 132. The 2 nd and 4 th linear portions 13ba and 13bb are connected to form an obtuse angle (e.g., 135 degrees). The 3 rd and 4 th linear portions 13ab and 13bb are arranged parallel to the perpendicular line L2.
The 1 st output unit 131 and the 2 nd output unit 132 are disposed outside the support portion 14 (see fig. 1 and 2) in a plan view. The 1 st detector circuit 15 is connected to the 1 st output unit 131. The 1 st detector circuit 15 detects the level of the microwave signal and outputs the detected level of the microwave signal as a control signal. The 2 nd detector circuit 16 is connected to the 2 nd output unit 132. The 2 nd detection circuit 16 detects the level of the microwave signal and outputs the detected level of the microwave signal as a control signal.
In the present embodiment, each of the 1 st detector circuit 15 and the 2 nd detector circuit 16 has a smoothing circuit (not shown) including a chip resistor and a schottky diode. The 1 st detector circuit 15 rectifies the microwave signal from the 1 st output unit 131, and converts the rectified microwave signal into a dc voltage. The converted dc voltage is output to the 1 st detection output unit 18.
Similarly, the 2 nd detector circuit 16 rectifies the microwave signal from the 2 nd output unit 132, and converts the rectified microwave signal into a dc voltage. The converted dc voltage is output to the 2 nd detection output unit 19.
The printed substrate 12 has four holes ( holes 20a, 20b, 20c, 20d) for mounting the printed substrate 12 on the waveguide 3. Copper foil serving as a ground is formed around the holes 20a, 20b, 20c, and 20d in the substrate back surface 12 b. The portion where the copper foil is formed has the same potential as the substrate front surface 12 a.
The printed circuit board 12 is fixed to the waveguide 3 by being screwed to the support 14 through the holes 20a, 20b, 20c, and 20d by screws 201a, 201b, 201c, and 201d (see fig. 1).
As shown in fig. 2, the support portion 14 has screw portions 202a, 202b, 202c, and 202d for screwing screws 201a, 201b, 201c, and 201d, respectively. The threaded portions 202a, 202b, 202c, 202d are formed on the flange portion provided on the support portion 14.
The support portion 14 has conductivity and is disposed so as to surround the cross opening 11 in a plan view. The support portion 14 functions as a shield for preventing the circularly polarized microwaves emitted from the cross hatch 11 from leaking to the outside of the support portion 14.
The support portion 14 includes a groove 141 and a groove 142 through which the 3 rd and 4 th linear portions 13ab and 13bb of the microstrip line 13 pass. According to this configuration, the 1 st output portion 131 and the 2 nd output portion 132 of the microstrip line 13 can be disposed outside the support portion 14. The grooves 141 and 142 function as extraction portions for extracting the microwave signal propagating through the microstrip line 13 to the outside of the support portion 14. The grooves 141 and 142 can be formed by recessing the flange portion of the support portion 14 so as to be spaced apart from the printed circuit board 12.
Fig. 1 and 2 show a connector 18a and a connector 19a connected to the 1 st detection output unit 18 and the 2 nd detection output unit 19 shown in fig. 4, respectively.
Next, the operation and action of the directional coupler 5 will be described.
First, the principle of emitting circularly polarized microwaves from the cross hatch 11 will be described with reference to fig. 5. In fig. 5, the magnetic field distribution 3d generated in the waveguide 3 is represented by a concentric ellipse of a broken line. The direction of the magnetic field distribution 3d is indicated by an arrow. The magnetic field distribution 3d moves in the waveguide 3 in the microwave transmission direction a1 with the passage of time.
At time t shown in fig. 5 (a), t0, the magnetic field distribution 3d is formed. At this time, the magnetic field indicated by the broken-line arrow B1 excites the 1 st long hole 11e of the cross opening 11. At time t shown in fig. 5 (B), t0+ t1, the magnetic field indicated by the broken-line arrow B2 excites the 2 nd long hole 11f of the cross hatch 11.
At time T shown in fig. 5 (c), T0+ T/2(T is the period of the in-tube wavelength of the microwave), the magnetic field shown by the broken-line arrow B3 excites the 1 st slot 11e of the cross hatch 11. At time T shown in fig. 5 (d), T0+ T/2+ T1, the magnetic field indicated by the broken-line arrow B4 excites the 2 nd long hole 11f of the cross hatch 11. At time T, T0+ T, the magnetic field indicated by broken-line arrow B1 excites the 1 st long hole 11e of the cross opening 11, similarly to time T, T0.
By repeating these states in sequence, the circularly polarized microwaves rotating counterclockwise (in the microwave rotation direction 32) are emitted from the intersection opening 11 to the outside of the waveguide 3.
Here, when the microwave propagating along arrow 30 shown in fig. 3 is a traveling wave and the microwave propagating along arrow 31 is a reflected wave, the traveling wave propagates in the same direction as propagation direction a1 shown in fig. 5. Therefore, as described above, the microwave of circular polarization rotated counterclockwise is radiated from the intersection opening 11 to the outside of the waveguide 3.
On the other hand, the reflected wave propagates in the direction opposite to the propagation direction a1 shown in fig. 5. Therefore, the microwave of circular polarization rotating clockwise is radiated from the intersection opening 11 to the outside of the waveguide 3.
The circularly polarized microwaves radiated out of the waveguide 3 are coupled to the microstrip line 13 opposite to the intersection opening 11. The microstrip line 13 outputs most of the microwaves radiated from the intersection 11 by the traveling wave propagating along the arrow 30 to the 1 st output unit 131.
On the other hand, the microstrip line 13 outputs most of the microwaves radiated from the cross opening 11 by the reflected waves propagating along the arrow 31 to the 2 nd output unit 132. This makes it possible to separate and detect the forward wave and the reflected wave with higher accuracy. This point will be described in more detail with reference to fig. 6.
Fig. 6 is a diagram for explaining the direction and amount of the microwave that propagates through the microstrip line 13 and changes with time. A gap exists between the microstrip line 13 and the cross opening 11. The time required for the microwaves to reach the microstrip line 13 will, by nature, delay the time for the microwaves to propagate in the gap. However, for convenience, this time delay is not assumed here.
Here, a region where the intersection opening 11 and the microstrip line 13 intersect in a plan view is referred to as a coupling region. The 1 st coupling point P1 is substantially the center of the coupling region where the 1 st long hole 11e intersects the microstrip line 13. The 2 nd coupling point P2 is substantially the center of the coupling region where the 2 nd long hole 11f intersects the microstrip line 13.
In fig. 6, the amount of microwaves (current flowing due to the linkage of the magnetic field) propagating through the microstrip line 13 is represented by the thickness of the line indicated by the solid arrow. That is, when the amount of microwaves propagating through the microstrip line 13 is large, the line is thick, and when the amount of microwaves propagating through the microstrip line 13 is small, the line is thin.
At time t shown in fig. 6 (a), t0, the magnetic field indicated by the broken-line arrow B1 excites the 1 st slot 11e of the cross hatch 11, and the microwave indicated by the thick solid-line arrow M1 is generated at the 1 st coupling point P1. The microwave propagates in the microstrip line 13 toward the 2 nd coupling point P2.
At time t shown in fig. 6 (B), t0+ t1, the magnetic field indicated by broken arrow B2 excites the 2 nd long hole 11f of the cross opening 11, and the microwave indicated by thick solid arrow M2 is generated at the 2 nd coupling point P2.
When the effective propagation time of the microwave by the microstrip line 13 between the 1 st coupling point P1 and the 2 nd coupling point P2 is set to time t1, the microwave generated at the 1 st coupling point P1 propagates to the 2 nd coupling point P2 at the time shown in fig. 6 (b) at the time shown in fig. 6 (a). That is, at the time shown in (b) of fig. 6, the microwave indicated by the solid arrow M1 and the microwave indicated by the solid arrow M2 are generated at the 2 nd coupling point P2.
Therefore, the two microwaves are added and propagated through the microstrip line 13 to the 2 nd output unit 132, and after a predetermined time, the sum is output to the 2 nd output unit 132. In the present embodiment, in order to set the effective propagation time to the time t1, the total distance of the 1 st transmission line 13a and the 2 nd transmission line 13b, which are farther from the tube axis L1 than the virtual straight line L3, is set to the effective length λ re1/4 of (1). With this configuration, the microstrip line 13 can be easily designed.
At time T shown in fig. 6 (c), T0+ T/2, the magnetic field indicated by the broken-line arrow B3 excites the 1 st slot 11e of the cross opening 11, and the microwave indicated by the thin solid-line arrow M3 is generated at the 1 st coupling point P1. The microwave propagates through the microstrip line 13 to the 1 st output section 131, and is output to the 1 st output section 131 after a predetermined time has elapsed.
The reason why the thickness of the solid arrow M3 is smaller than the thickness of the solid arrow M1 is as follows. The circularly polarized microwaves rotating counterclockwise (the direction 32 of rotation of the microwaves) as described above are emitted from the cross hatch 11.
At the time shown in fig. 6 (a), the microwave shown by the solid arrow M1 generated at the 1 st coupling point P1 propagates in substantially the same direction as the rotational direction of the microwave radiated from the intersection 11. Therefore, the energy of the microwave shown by the solid arrow M1 is not reduced.
On the other hand, at the time shown in fig. 6 (c), the microwave indicated by the solid arrow M3 generated at the 1 st coupling point P1 propagates in a direction substantially opposite to the rotational direction of the microwave radiated from the intersection 11. Thus, the energy of the coupled microwaves is reduced. Therefore, the amount of microwaves shown by the solid arrow M3 is smaller than the amount of microwaves shown by the solid arrow M1.
At time T shown in fig. 6 (d), T0+ T/2+ T1, the magnetic field indicated by the broken-line arrow B4 excites the 2 nd long hole 11f of the cross opening 11, and the microwave indicated by the thin solid-line arrow M4 is generated at the 2 nd coupling point P2. The microwave propagates toward the 1 st coupling point P1. The reason why the thickness of the solid arrow M4 is reduced is the same as the reason why the thickness of the solid arrow M3 is reduced.
At time T, T0+ T, the magnetic field indicated by the broken-line arrow B1 excites the 1 st long hole 11e of the cross hatch 11, similarly to the time T, T0 shown in fig. 6 (a). In this case, the microwave indicated by the thin solid arrow M4, which is not described when the time shown in fig. 6 (a) is present on the microstrip line 13.
The microwave shown by the thin solid arrow M4 propagates to the 1 st coupling point P1 at time T-T0 + T (i.e., T-T0). The microwave shown by the thin solid arrow M4 propagates in the opposite direction to the microwave shown by the thick solid arrow M1. Therefore, the microwaves shown by the solid arrow M4 are cancelled and lost, and are not output to the 1 st output unit 131.
Strictly speaking, the amount of microwaves propagating from the 1 st coupling point P1 at time t-t 0 is obtained by subtracting the amount of microwaves indicated by the thin solid arrow M4 from the amount of microwaves indicated by the thick solid arrow M1 (M1-M4). Therefore, the amount of microwaves outputted to the 2 nd output unit 132 is obtained by adding the amount of microwaves transmitted from the 2 nd coupling point P2 to the amount of microwaves indicated by the thick solid arrow M2 (M1+ M2-M4).
Even in consideration of this, the amount of microwaves (M1+ M2-M4) output to the 2 nd output part 132 is much more than the amount of microwaves (M3) output to the 1 st output part 131. Therefore, the microstrip line 13 outputs most of the microwaves radiated counterclockwise from the cross opening 11 by the reflected waves propagating along the arrow 31 to the 2 nd output unit 132. On the other hand, the microstrip line 13 outputs most of the microwaves radiated clockwise from the intersection 11 by the traveling wave propagating along the arrow 30 to the 1 st output unit 131.
The amount of microwaves radiated from the intersection opening 11 relative to the amount of microwaves propagating in the waveguide 3 is determined by the shape and size of the waveguide 3 and the intersection opening 11. For example, in the case of setting the above shape and size, the amount of microwaves radiated from the intersection opening 11 is about 1/100000 (about-50 dB) with respect to the amount of microwaves propagating in the waveguide 3.
Next, in the present embodiment, the total distance of the 1 st transmission line 13a and the 2 nd transmission line 13b, which are farther from the pipe axis L1 than the parallel line L4, is set to the effective length λreThe reason of 1/2 (1) is explained.
Fig. 7 is a diagram for explaining the direction and amount of the microwave that propagates through the microstrip line 13 and changes with time. Fig. 7 (a) to (d) are diagrams showing the states in which time t1/2 has elapsed from fig. 6 (a) to (d), respectively.
Although the description is omitted, the magnetic field distribution 3d moves in the propagation direction a1 of the microwave in the waveguide 3 with the passage of time. Therefore, as shown in (a) to (d) of fig. 7, the magnetic fields indicated by the broken line arrows B12, B23, B34, and B41 excite the 1 st long hole 11e and the 2 nd long hole 11 f. Thereby, the circularly polarized microwaves radiated out of the waveguide 3 are coupled to the microstrip line 13.
Here, a region where perpendicular line L2 and parallel line L4 intersect microstrip line 13 in plan view is referred to as a coupling region. The 3 rd coupling point P3 is substantially the center of the coupling region where the perpendicular line L2 intersects the microstrip line 13. The 4 th coupling point P4 is substantially the center of the coupling region where the parallel line L4 crosses the 1 st transmission line 13 a. The 5 th coupling point P5 is substantially the center of the coupling region where the parallel line L4 crosses the 2 nd transmission line 13 b.
At time t shown in fig. 7 (a), t0+ t1/2, the magnetic field indicated by broken line arrow B12 excites the cross opening 11, and the microwave indicated by thick solid line arrow M11 is generated at the 3 rd coupling point P3. The microwave propagates in the microstrip line 13 toward the 5 th coupling point P5.
At time t shown in fig. 7 (B), t0+ t1+ t1/2, the magnetic field shown by the dotted arrow B23 excites the cross hatch 11. Microwaves shown by thick solid line arrows M12a are generated at the 5 th coupling point P5, and microwaves shown by thin solid line arrows M12b are generated at the 4 th coupling point P4. The reason why the thickness of the solid arrow M12b is reduced is the same as the reason why the thickness of the solid arrow M3 is reduced.
When the effective propagation time of the microwave by the microstrip line 13 between the 3 rd coupling point P3 and the 5 th coupling point P5 is set to time t1, the microwave generated at the 3 rd coupling point P3 at the time shown in fig. 7 (a) propagates to the 5 th coupling point P5 at the time shown in fig. 7 (b). That is, at the time shown in fig. 7 (b), microwaves indicated by a thick solid arrow M11 and microwaves indicated by a thick solid arrow M12a are generated at the 5 th coupling point P5.
Therefore, the two microwaves are added and propagated through the microstrip line 13 to the 2 nd output unit 132, and after a predetermined time, the sum is output to the 2 nd output unit 132. In order to set the effective propagation time to the time t1, in the present embodiment, the distance of the 1 st transmission line 13a from the tube axis L1 with respect to the parallel line L4 is set to the effective length λ re1/4 of (1). The microwave shown by a thin solid arrow M12b generated at the 4 th coupling point P4 propagates through the microstrip line 13 to the 1 st output unit 131, and is output to the 1 st output unit 131 after a predetermined time.
At time T shown in fig. 7 (c), T0+ T/2+ T1/2, the magnetic field indicated by the broken-line arrow B34 excites the cross opening 11, and the microwave indicated by the thin solid-line arrow M13B is generated at the 3 rd coupling point P3. The microwave propagates through the microstrip line 13 to the 1 st output section 131. The reason why the thickness of the solid arrow M13b is reduced is the same as the reason why the thickness of the solid arrow M3 is reduced.
At time T shown in fig. 7 (d), T0+ T/2+ T1+ T1/2, the magnetic field shown by the dotted arrow B41 excites the cross hatch 11. The microwave shown by the arrow M14b is generated at the 5 th coupling point P5, and the microwave shown by the arrow M14a is generated at the 4 th coupling point P4. The microwave shown by the thin solid line arrow M14b propagates in the microstrip line 13 toward the 3 rd coupling point P3. The reason why the thickness of the solid arrow M14b is reduced is the same as the reason why the thickness of the solid arrow M3 is reduced.
The microwave shown by the thick solid arrow M14a propagates in the microstrip line 13 toward the 3 rd coupling point P3. When the effective propagation time of the microwave by the microstrip line 13 between the 3 rd coupling point P3 and the 4 th coupling point P4 is set to time t1, the microwave generated at the 3 rd coupling point P3 at the time shown in fig. 7 (c) propagates to the 4 th coupling point P4 at the time shown in fig. 7 (d).
That is, at the time shown in fig. 7 (d), microwaves indicated by a thin solid arrow M13b and microwaves indicated by a thick solid arrow M14a are generated at the 4 th coupling point P4. In order to make the above effective propagation timeThe time t1 is set, and in the present embodiment, the distance of the 2 nd transmission line 13b from the tube axis L1 to the parallel line L4 is set to the effective length λ re1/4 of (1).
That is, the total distance of the 1 st transmission line 13a and the 2 nd transmission line 13b, which are farther from the pipe axis L1 than the parallel line L4, is set to the effective length λ re1/2 of (1). The microwave shown by the thin solid arrow M13b propagates in the opposite direction to the microwave shown by the thick solid arrow M14 a. Therefore, the microwaves indicated by the thin solid line arrow M13b are cancelled and lost, and are not output to the 1 st output unit 131.
At time T, T0+ T1/2, the magnetic field indicated by broken-line arrow B12 excites the intersection 11, similarly to time T, T0+ T1/2 shown in fig. 7 (a). In this case, the microwave indicated by the thin solid arrow M14b, which is not described when the time shown in fig. 7 (a) is present on the microstrip line 13.
The microwave shown by the thin solid arrow M14b propagates to the 3 rd coupling point P3 at time T0+ T1/2. The microwaves indicated by the thin solid line arrow M14b propagate in the opposite direction to the microwaves indicated by the thick solid line arrow M11 and the thick solid line arrow M14 a. Therefore, the microwaves indicated by the thin solid line arrow M14b are cancelled and lost, and are not output to the 1 st output unit 131.
Strictly speaking, the amount of microwaves propagating from the 3 rd coupling point P3 at time t (t 0+ t 1/2) is obtained by subtracting the amount of microwaves indicated by the thin solid arrow M14b from the amount of microwaves indicated by the thick solid arrows M11 and M14a (M11+ M14a-M14 b). Therefore, the amount of microwaves output to the 2 nd output unit 132 is obtained by adding the amount of microwaves transmitted from the 3 rd coupling point P3 to the amount of microwaves indicated by the thick solid arrow M12a (M11+ M12a + M14a-M14 b).
Even in consideration of this, the amount of microwaves (M11+ M12a + M14a-M14b) output to the 2 nd output part 132 is much more than the amount of microwaves (M12b) output to the 1 st output part 131. Therefore, the microstrip line 13 outputs most of the microwaves radiated counterclockwise from the cross opening 11 by the reflected waves propagating in the direction of the arrow 31 to the 2 nd output unit 132. On the other hand, the microstrip line 13 outputs most of the microwaves radiated clockwise from the intersection 11 by the traveling wave propagating in the direction of the arrow 30 to the 1 st output unit 131.
The directional coupler 5 has an intersection opening 11 that emits circularly polarized microwaves and is disposed at a position that does not intersect the tube axis L1 of the waveguide 3 in a plan view. According to this structure, the rotation directions of the circularly polarized microwaves radiated from the cross opening 11 are opposite to each other in the forward wave and the reflected wave. The traveling wave and the reflected wave can be separated and detected by utilizing the difference in the rotational direction of the circularly polarized microwave.
In the directional coupler 5, the 1 st transmission line 13a has a1 st straight line part 13aa, and the 2 nd transmission line 13b has a 2 nd straight line part 13 ba. With this configuration, the bent portion of the microstrip line 13 can be reduced compared to the conventional one. The necessity of bending the microstrip line 13 at a right angle can be eliminated. The portion where the microstrip line 13 is bent can be separated from the region in the vertical direction of the intersection opening 11. As a result, the forward wave and the reflected wave can be separated and detected with higher accuracy.
In the directional coupler 5, the 1 st transmission line 13a and the 2 nd transmission line 13b are connected to each other at a position outside the rectangular region E1 and away from the tube axis L1 in a plan view. With this configuration, the portion where the microstrip line 13 is bent can be further away from the region in the vertical direction of the intersection opening 11. The 1 st linear portion 13aa and the 2 nd linear portion 13ba can be made longer, and the flow of current in the microstrip line 13 can be suppressed from being obstructed. As a result, the forward wave and the reflected wave can be separated and detected with higher accuracy.
In the directional coupler 5, the 1 st linear portion 13aa intersects the 1 st long hole 11e at a position closer to the opening distal end portion 11ea than the opening central portion 11c in a plan view. The 2 nd straight portion 13ba intersects the 2 nd long hole 11f at a position closer to the opening distal end portion 11fa than the opening center portion 11c in a plan view. Normally, a stronger magnetic field is generated around the opening end portions 11ea and 11fa than around the opening center portion 11 c. With the above structure, a stronger magnetic field is coupled to the microstrip line 13. Therefore, the current flowing in the microstrip line 13 becomes more. As a result, the forward wave and the reflected wave can be separated and detected with higher accuracy.
In the directional coupler 5, the 1 st linear portion 13aa is perpendicular to the 1 st long hole 11e in a plan view. According to this structure, the transmission direction of the microwave shown by the solid arrow M1 generated at the 1 st coupling point P1 is made to be the same as the rotation direction 32 of the microwave radiated from the cross hatch 11. This can further increase the amount of microwaves indicated by solid arrow M1.
The transmission direction of the microwave shown by the solid arrow M3 generated at the 1 st coupling point P1 is made opposite to the rotation direction 32 of the microwave radiated from the cross hatch 11. This can further reduce the amount of microwaves indicated by solid arrow M3. As a result, the forward wave and the reflected wave can be separated and detected with higher accuracy.
In the directional coupler 5, the 2 nd straight portion 13ba is perpendicular to the 2 nd long hole 11f in a plan view. With this structure, the transmission direction of the microwave indicated by the solid arrow M2 generated at the 2 nd coupling point P2 is made to be the same as the rotation direction 32 of the microwave radiated from the cross hatch 11. This can further increase the amount of microwaves indicated by solid arrow M2.
The transmission direction of the microwave shown by the solid arrow M4 generated at the 2 nd coupling point P2 is made opposite to the rotation direction 32 of the microwave radiated from the cross hatch 11. This can further reduce the amount of microwaves indicated by solid arrow M4. As a result, the forward wave and the reflected wave can be separated and detected with higher accuracy.
In the directional coupler 5, the microstrip line 13 has a1 st straight line portion 13aa, a 2 nd straight line portion 13ba, a 3 rd straight line portion 13ab, and a 4 th straight line portion 13 bb. The 1 st and 3 rd linear portions 13aa and 13ab adjacent to each other are connected to form an obtuse angle. The 2 nd and 4 th linear portions 13ba and 13bb adjacent to each other are connected to form an obtuse angle.
With this configuration, the portions of the microstrip line 13 bent at right angles can be reduced. This can suppress the current in the coupling line from being blocked. As a result, the forward wave and the reflected wave can be separated and detected with higher accuracy.
In the directional coupler 5, the total distance of the 1 st transmission line 13a and the 2 nd transmission line 13b, which are farther from the tube axis L1 than the virtual straight line L3, is set to the effective length λ re1/4 of (1). With this configuration, the forward wave and the reflected wave can be separated and detected with higher accuracy. The total distance is set to an effective length λreThe effective length λ may be set to approximately 1/4, but need not necessarily be set tore1/4 of (1).
In the directional coupler 5, the total distance of the 1 st transmission line 13a and the 2 nd transmission line 13b, which are farther from the tube axis L1 than the parallel line L4, is set to the effective length λ re1/2 of (1). With this configuration, the forward wave and the reflected wave can be separated and detected with higher accuracy. The total distance is set to an effective length λreThe effective length λ may be set to approximately 1/2, but need not necessarily be set tore1/2 of (1).
As shown in fig. 4, in the present embodiment, one end of the 1 st transmission line 13a and one end of the 2 nd transmission line 13b are connected so as to form a right angle. However, the present disclosure is not limited thereto. One end of the 1 st transmission line 13a may be connected to one end of the 2 nd transmission line 13b at a position deviated from the region of the intersection opening 11 in a plan view. In this region, the influence caused by the magnetic field is large.
Fig. 8A to 8D are plan views showing modifications 1 to 6 of the microstrip line 13. As shown in fig. 8A, the 1 st transmission line 13a and the 2 nd transmission line 13b may be bent so that a connection point between one end of the 1 st transmission line 13a and one end of the 2 nd transmission line 13b is distant from the opening center portion 11 c.
As shown in fig. 8B, the 1 st transmission line 13a and the 2 nd transmission line 13B may be bent so that a connection point between one end of the 1 st transmission line 13a and one end of the 2 nd transmission line 13B is close to the opening center portion 11 c. As shown in fig. 8C, the 1 st transmission line 13a and the 2 nd transmission line 13b may be bent so that a connection point between one end of the 1 st transmission line 13a and one end of the 2 nd transmission line 13b is close to the open center portion 11C.
In the present embodiment, the 1 st and 2 nd linear portions 13aa and 13ba correspond to the 1 st and 2 nd intersecting line portions, respectively. However, the present disclosure is not limited thereto. As shown in fig. 8D, the 1 st and 2 nd intersecting line portions may be arc-shaped portions 13ac and 13bc, respectively.
In the present embodiment, the 3 rd and 4 th linear portions 13ab and 13bb are parallel to the perpendicular line L2. However, the present disclosure is not limited thereto. As shown in fig. 8E, the 3 rd and 4 th linear portions 13ab and 13bb may be parallel to the parallel line L4.
In the present embodiment, the 1 st transmission line 13a and the 2 nd transmission line 13b have a plurality of straight portions. However, the present disclosure is not limited thereto. As shown in fig. 8F, the 1 st transmission line 13a and the 2 nd transmission line 13b may be formed of a single straight line portion.
In the present embodiment, the intersection opening 11 is formed line-symmetrically with respect to the perpendicular line L2. The perpendicular line L2 is perpendicular to the tube axis L1 and passes through the opening center portion 11 c. However, the present disclosure is not limited thereto. The intersection opening 11 may not be formed line-symmetrical with respect to the perpendicular line L2. For example, the 1 st long hole 11e and the 2 nd long hole 11f may intersect at positions offset from the respective longitudinal center portions. The length of the 1 st long hole 11e and the length of the 2 nd long hole 11f may be different from each other.
In these cases, the opening intersection portion where the 1 st long hole 11e and the 2 nd long hole 11f intersect is offset from the opening center portion 11 c. The intersection opening 11 may be formed to be line-symmetric with respect to a straight line slightly inclined with respect to the perpendicular line L2 in a plan view.
The structure of the microwave heating device 10 of the present embodiment will be described below with reference to fig. 9. As shown in fig. 9, microwave heating apparatus 10 includes heating chamber 1, microwave generating unit 2, waveguide 3, and microwave radiating unit 4.
The heating chamber 1 accommodates an object to be heated. The microwave generating unit 2 generates microwaves. The waveguide 3 propagates the microwave generated by the microwave generating unit 2. The microwave radiation unit 4 is disposed below the bottom surface 1a of the heating chamber 1, and radiates microwaves propagating through the waveguide 3 to the heating chamber 1. A directional coupler 5 is disposed on a wide surface 3a (see fig. 1 and 2) of the waveguide 3 between the microwave generating unit 2 and the microwave radiating unit 4.
The directional coupler 5 detects the detection signal 5a based on the traveling wave propagating through the waveguide 3 from the microwave generating unit 2 to the microwave radiating unit 4. The directional coupler 5 detects the detection signal 5b based on the reflected wave propagating through the waveguide 3 from the microwave radiation unit 4 to the microwave generation unit 2. The directional coupler 5 transmits the detection signals 5a and 5b to the control unit 6.
The control unit 6 receives a signal 8 in addition to the detection signals 5a, 5 b. The signal 8 includes heating conditions set by an input unit (not shown) of the microwave heating device 10, and the weight of the object to be heated and the amount of steam detected by a sensor (not shown). The control section 6 controls the driving power supply 7 and the motor 9 based on the detection signals 5a, 5b and the signal 8. The driving power supply 7 supplies power for generating microwaves to the microwave generating unit 2. The motor 9 rotates the microwave radiation unit 4. In this way, the microwave heating device 10 heats the object to be heated stored in the heating chamber 1 by the microwaves supplied to the heating chamber 1.
As the object to be heated is heated, the object to be heated is physically changed. The amount of the reflected wave varies according to the physical change. By detecting the change in the amount of reflected waves using directional coupler 5, microwave heating device 10 can grasp the progress of heating of the object to be heated. The microwave heating device 10 can also grasp the change in the state of the object to be heated, and the type and amount of the object to be heated. Therefore, according to the present embodiment, a microwave heating device with high convenience can be provided.
Industrial applicability
The directional coupler of the present disclosure may be used in a microwave heating device for domestic or commercial use.
Description of the reference symbols
1: a heating chamber; 1 a: a bottom surface; 2: a microwave generating section; 3: a waveguide; 3 a: a wide breadth; 3 d: a magnetic field distribution; 4: a microwave radiation unit; 5: a directional coupler; 5a, 5 b: detecting a signal; 6: a control unit; 7: a drive power supply; 8: a signal; 9: a motor; 10: a microwave heating device; 11: a cross opening; 11 c: an open central portion; 11 d: a width; 11 e: a1 st long hole; 11ea, 11 fa: an opening end portion; 11 f: a 2 nd long hole; 11 w: a length; 12: a printed substrate; 12 a: a front surface of the substrate; 12 b: the reverse side of the substrate; 13: a microstrip line; 13 a: 1 st transmission line; 13 aa: a1 st straight line part; 13 ab: a 3 rd linear part; 13ac, 13 bc: a circular arc portion; 13 b: a 2 nd transmission line; 13 ba: a 2 nd straight line part; 13 bb: a 4 th linear part; 14: a support portion; 15: a1 st detector circuit; 16: a 2 nd detection circuit; 18: a1 st detection output unit; 18a, 19 a: a connector; 19: a 2 nd detection output section; 20 a: an aperture; 30: an arrow; 31: an arrow; 131: a1 st output unit; 132: a 2 nd output unit; 141. 142: a groove; 201 a: a screw; 202 a: a threaded portion; e1: a rectangular area; l1: a tubular shaft; l2: a vertical line; l3: an imaginary straight line; l4: parallel lines; p1: 1 st coupling point; p2: a 2 nd coupling point; p3: a 3 rd coupling point; p4: a 4 th coupling point; p5: the 5 th coupling point.
Claims (9)
1. A directional coupler having an opening portion disposed on a wall surface of a waveguide and a coupling line disposed outside the waveguide, the directional coupler separating and detecting a traveling wave and a reflected wave propagating through the waveguide,
the opening has a1 st long hole and a 2 nd long hole which are arranged at positions which do not intersect with the tube axis of the waveguide in a plan view and intersect with each other,
the coupled line has a1 st transmission line and a 2 nd transmission line,
the 1 st transmission line has a1 st cross line portion, the 1 st cross line portion extending so as to be apart from the pipe axis as approaching from one end of the pipe axis to a perpendicular line perpendicular to the pipe axis through an opening intersection portion where the 1 st long hole and the 2 nd long hole intersect, and intersecting the 1 st long hole at a position apart from the pipe axis than the opening intersection portion,
the 2 nd transmission line has a 2 nd intersecting line portion, the 2 nd intersecting line portion extending away from the tube axis as approaching the perpendicular line from the other end of the tube axis in a plan view and intersecting the 2 nd long hole at a position farther from the tube axis than the opening intersecting portion,
one end of the 1 st transmission line is connected to one end of the 2 nd transmission line at a position deviated from the region of the opening in a plan view.
2. The directional coupler of claim 1,
the 1 st transmission line and the 2 nd transmission line are connected to each other at: the position is outside a rectangular region circumscribed with the opening in a plan view and is further away from the pipe shaft than the rectangular region.
3. The directional coupler of claim 1,
at least one of the 1 st cross line portion and the 2 nd cross line portion intersects the corresponding 1 st long hole or the 2 nd long hole at a position closer to an opening distal end portion than the opening cross portion in a plan view.
4. The directional coupler of claim 1,
at least one of the 1 st cross line portion and the 2 nd cross line portion is perpendicular to the corresponding 1 st long hole or the 2 nd long hole in a plan view.
5. The directional coupler of claim 1,
the coupling line has a plurality of straight line portions including the 1 st and 2 nd crossover portions, and two adjacent straight line portions of the plurality of straight line portions are connected so as to form an obtuse angle.
6. The directional coupler of claim 5, wherein,
the plurality of linear portions include a linear portion connecting the other end of the 1 st cross line portion and the 1 st output portion, and a linear portion connecting the 2 nd cross line portion and the 2 nd output portion.
7. The directional coupler of claim 1,
1/4 in which the total distance of the 1 st transmission line and the 2 nd transmission line that are farther from the tube axis than a virtual straight line that passes through the 1 st coupling point, which is the intersection of the 1 st crossline portion and the 1 st long hole, and the 2 nd coupling point, which is the intersection of the 2 nd crossline portion and the 2 nd long hole, in a plan view, is set to an effective length.
8. The directional coupler of claim 1,
a total distance of the 1 st transmission line and the 2 nd transmission line, which is farther from the pipe axis than a parallel line that passes through the opening intersection in a plan view and is parallel to the pipe axis, is set to 1/2 that is an effective length.
9. A microwave heating apparatus, wherein the microwave heating apparatus has the directional coupler of claim 1.
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| JP2018-081499 | 2018-04-20 | ||
| JP2018081499 | 2018-04-20 | ||
| PCT/JP2019/016074 WO2019203170A1 (en) | 2018-04-20 | 2019-04-15 | Directional coupler and microwave heating device provided with same |
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| Publication number | Publication date |
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| JP7178563B2 (en) | 2022-11-28 |
| EP3783736A1 (en) | 2021-02-24 |
| JPWO2019203170A1 (en) | 2021-05-13 |
| EP3783736A4 (en) | 2021-06-16 |
| JP2022189917A (en) | 2022-12-22 |
| CN111033889B (en) | 2021-10-08 |
| JP7454770B2 (en) | 2024-03-25 |
| EP3783736B1 (en) | 2023-11-22 |
| WO2019203170A1 (en) | 2019-10-24 |
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