JPH113776A - High-frequency heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple high-frequency heating device with a structure whereby desired finish of an object to be heated in a heating chamber can be obtained. SOLUTION: A radiant antenna 11 which has an expanded part 15 with an enlarged surface area is provided movably in a heating chamber 4, electromagnetic waves generated in a magnetron 2 is introduced to the radiant antenna 11 via a wave guide 3 and a joint part 10 and an object 6 to be heated is locally heated by applying concentrated radiation of the electromagnetic waves from the expanded part 15. The joint part 10 of the radiant antenna is connected to a rotary shaft 13 of a stepping motor 12, a position of the expanded part 15 can be rotated and moved with rispect to the object 6 to be heated by its rotation. When heating the object 6 placed on a support plate 14 for the object by applying electromagnetic wave form a lower part in its neighborhood, it is heated so that desired a finish can be obtained by moving the heating position to be heated locally. In addition, the size of the expanded part 15 is set to be an integral multiple of a half wave length of the electromagnetic waves applied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency heating apparatus provided with a radiation antenna capable of controlling a heating distribution when an object to be heated is subjected to dielectric heating by electromagnetic waves.

[0002]

2. Description of the Related Art A conventional high-frequency heating device will be described below. Conventionally, this type of high-frequency heating apparatus has been disclosed in
The one disclosed in Japanese Patent No. 38857 is generally used. As shown in FIG. 7, this high-frequency heating device includes a turntable 1, and an electromagnetic wave emitted from a magnetron 2 as an electromagnetic wave generating means is transmitted by a waveguide 3, and the shape of the heating chamber 4 and the electromagnetic wave Is distributed in the heating chamber 4 as a standing wave determined by the position of the opening 5 from which the light is radiated, and is heated according to the electric field component of the electromagnetic wave in each part of the object 6 to be heated and the dielectric loss of each part. . In this conventional example,
Since the heating distribution of the object to be heated 6 is substantially determined by the standing wave distribution of the electromagnetic wave, the turntable 1 for suppressing the unevenness of the heating distribution is driven to rotate, so that the concentric heating distribution is made uniform.

Further, as disclosed in Japanese Patent Application Laid-Open No. Hei 7-198147, there has been a method of switching a plurality of openings 5. In this high-frequency heating apparatus, as shown in FIGS. 8 and 9, 20 waveguides 3 are arranged in a matrix outside the bottom surface of a heating chamber 4, and power is supplied to each of the waveguides 3. It was selectively controlled. At this time, which of the waveguides 3 is supplied with power is controlled by temperature detecting means 7 for detecting a local temperature in the heating chamber 4, and 20 mirrors are provided vertically above each opening 5. Equipped with 8, 5
Infrared rays were guided to five sets of temperature detecting means 7 via the set of concave mirrors 9 to detect local temperatures.

[0004]

However, in the conventional high-frequency heating apparatus as shown in FIG. 7, when the waveguide 3 and the heating chamber 4 are connected to each other to introduce an electromagnetic wave into the heating chamber 4, the heating is performed. Since the appropriate position of the opening 5 for making the heating distribution uniform depends on the material and the shape of the heating object 6, one opening 5
However, it is not possible to uniformly heat all of the objects to be heated 6 by using only the heating method. For example, it is generally known that when a flat object 6 to be heated is heated by a conventional microwave oven, heating proceeds from the edge of the object 6 to be heated, and uneven heating occurs such that the center is not heated. At this time, in the configuration shown in FIG. 7, the heating distribution can be made uniform on the concentric circle by the rotation of the turntable 1, but the heating distribution in the radial direction or the vertical direction cannot be improved.

On the other hand, in the conventional high-frequency heating apparatus as shown in FIGS. 8 and 9, the emphasis is placed on the heating by the radiation wave rather than the heating by the standing wave, and the radiation of the electromagnetic wave from below the vicinity of the object 6 to be heated. This is a method of controlling the position, and it is possible to locally heat an arbitrary position of the object to be heated 6 by the radiation position. However, it is necessary to install many waveguides 3, and
In order to obtain a desired finished state, it is necessary to switch the power supply to each of the waveguides 3, so that there is a problem that the configuration becomes complicated.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a high-frequency heating device having a simple structure and capable of finishing a desired cooking state.

[0007]

According to a first aspect of the present invention, a radiating antenna having an enlarged portion having a partially increased surface area is provided so as to be movable in a heating chamber, and the radiating antenna is provided on an object to be heated in the heating chamber. This is a high-frequency heating device in which electromagnetic waves are radiated intensively from a part.

According to the present invention, since the electromagnetic wave can be radiated intensively from the enlarged portion of the movable radiating antenna, the object to be heated can be locally heated, and one of many waveguides can be heated. And an operation equivalent to the means of selecting and heating can be realized.

According to a second aspect of the present invention, the position of the radiation antenna with respect to the object to be heated is controlled to control the finish of cooking of the object to be heated.
This is a high-frequency heating device according to the present invention.

According to the present invention, since the position of the radiation antenna can be moved, it is possible to control the movement of the position where the object to be heated is heated, and to perform the cooking so that the finished state is uniform.

According to a third aspect of the present invention, there is provided the high-frequency heating device according to the first or second aspect, wherein the size of the enlarged portion is an integral multiple of a half wavelength of the radiated electromagnetic wave.

According to the present invention, the expanding section can efficiently radiate electromagnetic waves as an antenna having an integral multiple of half a wavelength.

According to a fourth aspect of the present invention, there is provided a high-frequency heating apparatus according to the first or second aspect, wherein the axial length of the shaft portion excluding the enlarged portion of the radiation antenna is an integral multiple of a half wavelength of the radiated electromagnetic wave. Device.

According to the present invention, an electromagnetic wave can be efficiently introduced into the enlarged portion by mounting an integral multiple of a half wavelength on the shaft portion.

According to a fifth aspect of the present invention, the axial length of the shaft portion excluding the enlarged portion of the radiation antenna from the coupling portion with the waveguide is an odd multiple of 1/4 wavelength of the radiated electromagnetic wave. A high-frequency heating device according to claim 1 or 2.

According to the present invention, the connecting portion becomes a belly and
Since an odd multiple of / 4 wavelength is on the shaft portion, the electromagnetic wave can be efficiently introduced into the enlarged portion.

According to a sixth aspect of the present invention, when the size of the enlarged portion is an odd multiple of a half wavelength of the radiated electromagnetic wave, the electric field on the radiation antenna is maximized so that the electric field intensity at the center of the enlarged portion is maximized. The high-frequency heating device according to claim 3, wherein an intensity distribution is set.

According to the present invention, it is possible to set an optimum state in which the enlarged portion operates as a radiation antenna having an odd multiple of a half wavelength of an electromagnetic wave.

According to a seventh aspect of the present invention, when the size of the enlarged portion is set to an integral multiple of one wavelength of the radiated electromagnetic wave, the electric field intensity at the center of the enlarged portion is minimized on the radiation antenna. The high-frequency heating device according to claim 3, wherein an electric field intensity distribution is set.

According to the present invention, it is possible to set an optimum state in which the expanding portion operates as a radiation antenna having an integral multiple of one wavelength of the electromagnetic wave.

According to the present invention, the shaft width of the shaft portion excluding the enlarged portion of the radiation antenna is not larger than １ ／ of the wavelength of the radiated electromagnetic wave. A high-frequency heating device according to any one of the preceding claims.

According to the present invention, the radiation of electromagnetic waves from the shaft portion can be suppressed and the electromagnetic waves can be radiated efficiently from the enlarged portion in a concentrated manner, thereby suppressing undesired heating due to the radiation from the shaft portion. Can be.

[0023]

The high-frequency heating apparatus according to claim 1 is provided with a radiating antenna having an enlarged portion having a partially increased surface area so as to be movable in a heating chamber, and the heating object in the heating chamber is provided with the enlarged antenna. And a high-frequency heating device in which electromagnetic waves are radiated intensively.

In the present invention, the radiating antenna is formed by printing a conductor on the surface of an insulator and increasing the surface area of a part of the conductor to form an enlarged portion. In the embodiment, the surface area near the tip is circular. The enlarged portion is set to be an integral multiple of a half wavelength of the electromagnetic wave, but the shape of the enlarged portion is not limited to a circle. Further, a coupling portion with the waveguide is provided near the other end of the radiation antenna, and a portion of the radiation antenna reaching the enlarged portion is used as a shaft portion, and electromagnetic waves are propagated to the enlarged portion via the shaft portion. Also,
The radiating antenna is movable in a heating chamber, and in the embodiment, the coupling portion is rotatable by being connected to a rotation shaft of a stepping motor, but is not limited to the rotational movement.

According to a second aspect of the present invention, in the high frequency heating apparatus according to the first aspect, the position of the radiation antenna with respect to the object to be heated is controlled to control the finish of the cooking of the object to be heated. I do.

In the present invention, the position of the radiating antenna is moved within the heating chamber, and the position at which the object to be heated is sequentially moved is changed by changing the relative position of the enlarged portion which mainly emits electromagnetic waves with respect to the object to be heated. In this embodiment, the object to be heated is uniformly heated so as to obtain a desired cooking state. In this embodiment, the position of the radiation antenna is moved by rotating a stepping motor. The pattern to be moved can be set in advance in accordance with the material, shape, size, and the like of the object to be heated.

According to a third aspect of the present invention, there is provided the high-frequency heating apparatus according to the first or second aspect, wherein the size of the enlarged portion is an integral multiple of a half wavelength of the radiated electromagnetic wave.

In the present invention, the enlargement portion is set so that an integral multiple of a half wavelength of the electromagnetic wave is placed on the enlargement portion, and the enlargement portion radiates the electromagnetic wave efficiently as an antenna having an integral multiple of the half wavelength. This setting includes a case where an integral multiple of one wavelength is used. In the embodiment, the diameter of the circular enlarged portion is set to be a half wavelength,
The enlarged portion is configured to be a half-wave antenna.

According to a fourth aspect of the present invention, in the high-frequency heating device, the axial length of the shaft excluding the enlarged portion of the radiation antenna is an integral multiple of a half wavelength of the radiated electromagnetic wave. A heating device.

In the present invention, it is set so that an electromagnetic wave propagates such that an integral multiple of a half wavelength of an electromagnetic wave is placed on a shaft portion excluding the enlarged portion, and the enlarged portion can be an antenna having an integral multiple of a half wavelength. In this case, an integral multiple of a half wavelength rides on the entire radiation antenna, and the electromagnetic wave propagates efficiently to the enlarged portion. In this embodiment, when the enlarged portion is a half-wavelength antenna, three half-wavelengths are set on the shaft portion.

According to a fifth aspect of the present invention, in the high-frequency heating device, the axial length of the shaft portion excluding the enlarged portion of the radiation antenna from the coupling portion with the waveguide is an odd multiple of 1/4 wavelength of the radiated electromagnetic wave. The high-frequency heating device according to claim 1 or 2, wherein

In the present invention, an odd multiple of 1/4 wavelength of the electromagnetic wave rides from the enlarged portion to the coupling portion in the shaft portion, and the electromagnetic wave is propagated so that the enlarged portion becomes an antenna having an integral multiple of half a wavelength. Set. In this case, the coupling portion becomes an antinode of the electromagnetic wave, and the electromagnetic wave is efficiently transmitted from the waveguide to the radiation antenna, and propagates efficiently to the enlarged portion.
In the embodiment, when the expanding portion is a full-wavelength antenna, five quarter wavelengths are set.

According to a sixth aspect of the present invention, when the size of the enlarged portion is set to an odd multiple of a half wavelength of the radiated electromagnetic wave, the high-frequency heating device is mounted on the radiating antenna such that the electric field intensity at the center of the enlarged portion becomes maximum. The high-frequency heating apparatus according to claim 3, wherein the electric field intensity distribution is set as follows.

In the present invention, the electric field intensity at the center of the enlarged portion is set to be maximum, and the enlarged portion efficiently emits electromagnetic waves as an antenna having an odd multiple of half a wavelength. The electric field strength at the center is set to be maximum with the diameter of the circular enlarged portion being half the wavelength, and the enlarged portion is a half-wavelength antenna.

According to a seventh aspect of the present invention, when the size of the enlarged portion is set to an integral multiple of one wavelength of the radiated electromagnetic wave, the high-frequency heating device according to the seventh aspect of the present invention may be arranged so that the electric field intensity at the center of the enlarged portion becomes minimum. The high-frequency heating apparatus according to claim 3, wherein the electric field intensity distribution is set as follows.

In the present invention, the electric field intensity at the center of the enlarged portion is set to be minimum, and the enlarged portion efficiently radiates electromagnetic waves as an antenna having an integral multiple of one wavelength. The diameter of the circular enlarged portion is set to one wavelength so that the electric field intensity at the center is minimized, and the enlarged portion is a full-wavelength antenna.

In the high-frequency heating device according to the eighth aspect, the axial width of the shaft portion excluding the enlarged portion of the radiating antenna is set to a size not exceeding １ ／ of the wavelength of the radiated electromagnetic wave. The high-frequency heating device according to any one of the above.

In the present invention, the axial width of the shaft portion is set to 1 / the wavelength.
4 or less to reduce the emission of electromagnetic waves from the shaft portion, but in the embodiment, it is configured by a strip-shaped conductor that is thinner than the diameter of the circular enlarged portion and has a width of 1/4 wavelength or less. doing.

Hereinafter, embodiments will be described. (Embodiment 1) Hereinafter, a first embodiment of a high-frequency heating apparatus according to the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing the structure of this embodiment. Note that the same components as those of the conventional example shown in FIG. 7 are assigned the same reference numerals, and detailed description will be omitted. In the figure, an electromagnetic wave radiated from a magnetron 2 is applied to a waveguide 3 and a coupling portion 1.
0, and enters the heating chamber 4 via the radiation antenna 11 to heat the object 6 to be heated. Here, the rotating shaft 13 of the stepping motor 12 exists below the waveguide 3,
Connected to the coupling unit 10. In this embodiment, the turntable 1, the plate, and the motor for rotating the turntable 1 in the conventional example do not exist, and the object 6 to be heated is merely placed on the object supporting plate 14.

The operation of the above configuration will be described. FIG. 2 is a plan view showing the configuration of the radiation antenna 11, and FIG. 3 is a side view showing the configuration of the radiation antenna 11. In the figure,
The electromagnetic wave that has entered from the coupling part 10 is transmitted strongly in the longitudinal direction of the radiation antenna 11. At this time, the radiation antenna 11
If the shaft portion 16 has the same width up to the tip, the electromagnetic wave is radiated from every place of the radiation antenna 11, but in the present embodiment, the enlarged portion 15 in which the surface area of the radiation antenna 11 is partially increased is provided. The electromagnetic waves are radiated from the unit 15 in a concentrated manner. In the conventional configuration shown in FIG. 7, the object to be heated 6 is uniformly heated by rotating the turntable 1. However, in the configuration of the present embodiment, the enlarged portion 15 of the radiation antenna 11 is controlled by the stepping motor 12. The object to be heated 6 can be locally heated by moving it to the portion of the object 6 to be heated most, and can be finished to a desired state by sequentially changing the heating position. For example, the radiation antenna 11 can be moved by the stepping motor 12 according to a movement pattern set in advance according to the material, shape, size, and the like of the object 6 to be heated. In the configuration of the present embodiment, it is not possible to move the enlarged portion 15 directly below an arbitrary portion of the object 6 to be heated. However, by using a plurality of stepping motors and gears, an arbitrary portion of the object 6 to be heated can be obtained. It is also possible to move the enlarged portion 15 directly below the location.

In particular, assuming that the wavelength of the electromagnetic wave to be radiated is λ, the size D of the enlarged portion 15 of the radiation antenna 11 is nλ
/ 2 (where n is an integer of 1 or more)
It can work like a patch antenna. The patch antenna is a kind of microstrip antenna that is made by printing on a substrate, and in recent years, there is much demand,
It is also used for array antennas of the most reliable weather satellite radar.

In the configuration shown in FIGS. 2 and 3, the size D of the enlarged portion 15 of the radiation antenna 11 is set to (2m-1) λ
/ 2 (where m is an integer of 1 or more),
When m = 1, it operates as a so-called half-wave antenna. FIG. 4 is a side view schematically showing the electric field intensity distribution on the radiation antenna 11. As shown in FIG. 4, since the electric field strength is zero at both ends of the radiation antenna 11, the lengths A to A of the shaft portion 16 not including the enlarged portion 15 of the radiation antenna 11 are set.
B needs to be kλ / 2 (where k is an integer of 1 or more). In FIG. 4, the length A to B of the shaft portion 16 not including the enlarged portion 15 of the radiation antenna 11 is 3λ / 2. In addition, the lengths A to C of the shaft portion 16 from the coupling portion 10 not including the enlarged portion 15 of the radiation antenna 11 need to be (2k-1) λ / 4 (where k is an integer of 1 or more). . In FIG. 4, the lengths A to C of the shaft portion 16 not including the enlarged portion 15 of the radiation antenna 11 are 5λ / 4. Shaft 16 of radiation antenna 11
By setting the length in this way, the electromagnetic wave can be efficiently transmitted on the shaft portion 16. The size D of the enlarged portion 15 of the radiation antenna 11 is (2m-1) λ /
2 (where m is an integer of 1 or more)
By connecting the enlarged portion 15 to the shaft portion 16 so that the electric field strength is maximized at the center E of 5, the amount of electromagnetic waves emitted from the enlarged portion 15 can be increased.

In order to reduce the amount of electromagnetic waves radiated from the shaft 16 of the radiation antenna 11, it is effective to set the shaft width F of the shaft 16 to λ / 4 or less.

Although FIGS. 2, 3 and 4 show the case where the enlarged portion 15 is circular, it may be a polygon such as a quadrangle, an ellipse, a line, or a combination thereof. Similar effects can be obtained.

(Embodiment 2) Hereinafter, a second embodiment of the high-frequency heating device of the present invention will be described with reference to the drawings. FIG. 5 is a plan view showing the configuration of the radiation antenna in the present embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description is omitted. The overall configuration is the same as in FIG. This embodiment is different from the first embodiment in that the size of the enlargement unit 15 is not an integral multiple of a half wavelength but 1
That is, it is set to an integral multiple of the wavelength. The operation of the radiation antenna in the present embodiment is the same as that of the first embodiment, but in the present embodiment shown in FIG. 5, the size D of the enlarged portion 15 of the radiation antenna 11 is mλ (where m is an integer of 1 or more. ), That is, an integer multiple of the wavelength, and when m = 1, it operates as a so-called full-wavelength antenna.

FIG. 6 is a side view schematically showing the electric field intensity distribution on the radiation antenna 11. As shown in FIG. 6, since the size D of the enlarged portion 15 of the radiation antenna 11 is mλ (where m is an integer of 1 or more), the electric field strength is minimized at the center E of the enlarged portion 15. Enlarged part 15 to shaft part 1
6, the amount of radiation of the electromagnetic wave from the enlarged portion 15 can be increased.

Although FIGS. 5 and 6 show an example in which the enlarged portion 15 is a circular radiating antenna, the same applies to polygons such as a quadrangle, an ellipse, a line, or a combination thereof. The effect of can be obtained.

[0049]

According to the first aspect of the present invention, a radiating antenna having an enlarged portion having a partially increased surface area is provided so as to be movable into a heating chamber, and an electromagnetic wave is applied to an object to be heated in the heating chamber from the enlarged portion. By using a high-frequency heating device that radiates intensively, electromagnetic waves can be radiated intensively from the enlarged portion of the movable radiating antenna, so that any desired position of the object to be heated can be intensively heated. it can.

According to a second aspect of the present invention, the position of the radiation antenna with respect to the object to be heated is controlled to control the finish of cooking of the object to be heated.
, The position of the radiation antenna is appropriately moved with respect to the object to be heated, the position at which the object to be heated is controlled, and the cooking is performed so that the finished state becomes uniform. be able to.

According to a third aspect of the present invention, there is provided the high-frequency heating device according to the first or second aspect, wherein the size of the enlarged portion is an integral multiple of a half wavelength of the radiated electromagnetic wave. Can be efficiently radiated as an antenna having an integral multiple of a half wavelength, and a desired position of the object to be heated can be locally and efficiently heated.

According to a fourth aspect of the present invention, in the first or second aspect, the axis length of the shaft portion excluding the enlarged portion of the radiation antenna is an integral multiple of a half wavelength of the radiated electromagnetic wave. By using the related high-frequency heating device, an electromagnetic wave can be efficiently introduced into the enlarged portion, the amount of electromagnetic wave emitted from the enlarged portion is increased, and a desired position of the object to be heated is locally and efficiently heated. be able to.

According to a fifth aspect of the present invention, the axial length of the shaft portion excluding the enlarged portion of the radiation antenna from the coupling portion with the waveguide is an odd multiple of 1/4 wavelength of the radiated electromagnetic wave. According to the high-frequency heating device according to claim 1 or 2, an electromagnetic wave can be efficiently introduced into the enlarged portion, the amount of the electromagnetic wave emitted from the enlarged portion can be increased, and desired heating of the object to be heated can be achieved. The position can be locally and efficiently heated.

According to a sixth aspect of the present invention, when the size of the enlarged portion is an odd multiple of a half wavelength of the radiated electromagnetic wave, the electric field on the radiation antenna is maximized so that the electric field intensity at the center of the enlarged portion is maximized. The high-frequency heating device according to claim 3, wherein the intensity distribution is set, allows the expansion unit to be set to an optimal state of operating as a radiation antenna having an odd multiple of half a wavelength of an electromagnetic wave, thereby increasing radiation from the expansion unit. be able to.

According to a seventh aspect of the present invention, when the size of the enlarged portion is set to an integral multiple of one wavelength of the radiated electromagnetic wave, the electric field intensity at the center of the enlarged portion is minimized on the radiation antenna. The high frequency heating device according to claim 3, wherein the electric field intensity distribution is set, whereby the expansion unit can be set to an optimal state in which the expansion unit operates as a radiation antenna having an integral multiple of one wavelength of the electromagnetic wave, thereby increasing the radiation from the expansion unit. Can be.

According to the present invention, the shaft width of the shaft portion excluding the enlarged portion of the radiation antenna is set to a size not exceeding １ ／ of the wavelength of the radiated electromagnetic wave. A high-frequency heating device according to any one of the preceding claims.

According to the present invention, the radiation of electromagnetic waves from the shaft portion can be suppressed, the electromagnetic waves can be efficiently radiated from the enlarged portion, and undesired heating due to the radiation from the shaft portion can be suppressed. The heated object can be brought into a desired finished state.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a high-frequency heating device according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a configuration of a radiation antenna according to the embodiment.

FIG. 3 is a side view showing the configuration of the radiation antenna in the embodiment.

FIG. 4 is a side view schematically showing an electric field intensity distribution on the radiation antenna in the embodiment.

FIG. 5 is a plan view showing a configuration of a radiation antenna according to a second embodiment of the high-frequency heating device of the present invention.

FIG. 6 is a side view schematically showing an electric field intensity distribution on the radiation antenna in the embodiment.

FIG. 7 is a cross-sectional view showing a configuration of a conventional high-frequency heating device.

FIG. 8 is a perspective view showing another configuration of a conventional high-frequency heating device.

FIG. 9 is a sectional view showing the configuration of the conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Turntable 2 Magnetron 3 Waveguide 4 Heating chamber 5 Opening 6 Heated object 7 Temperature detecting means 8 Mirror 9 Concave mirror 10 Coupling part 11 Radiation antenna 12 Stepping motor 13 Rotation axis 14 Heated object support plate 15 Enlarged part 16 Shaft E Center F Shaft width

Claims (8)

[Claims] A high-frequency radiation antenna having an enlarged portion having a partially increased surface area is provided so as to be movable in a heating chamber, and an electromagnetic wave is radiated from the enlarged portion to an object to be heated in the heating chamber. Heating equipment. 2. The high-frequency heating apparatus according to claim 1, wherein the position of the radiation antenna with respect to the object to be heated is controlled to control the finish of cooking of the object to be heated. 3. The high-frequency heating device according to claim 1, wherein the size of the enlarged portion is an integral multiple of a half wavelength of the radiated electromagnetic wave. 4. The high-frequency heating device according to claim 1, wherein an axis length of the shaft portion excluding the enlarged portion of the radiation antenna is an integral multiple of a half wavelength of the radiated electromagnetic wave. 5. The shaft of the radiation antenna excluding an enlarged portion,
The axial length from the joint with the waveguide is one of the radiated electromagnetic waves.
3. The high-frequency heating apparatus according to claim 1, wherein the high-frequency heating apparatus has an odd multiple of / 4 wavelength. 6. The electric field intensity distribution on the radiation antenna is set such that the electric field intensity at the center of the enlarged portion is maximized when the size of the enlarged portion is an odd multiple of a half wavelength of the radiated electromagnetic wave. Item 4. The high-frequency heating device according to Item 3. 7. One of the electromagnetic waves radiated through the size of the enlarged portion.
4. The high-frequency heating apparatus according to claim 3, wherein the electric field intensity distribution on the radiation antenna is set such that the electric field intensity at the center of the enlarged portion is minimized when the wavelength is an integral multiple of the wavelength. 8. The illuminating antenna according to claim 1, wherein the axis width of the shaft portion excluding the enlarged portion of the radiating antenna does not exceed １ ／ of the wavelength of the radiated electromagnetic wave. High frequency heating device.