JP2007295350A - Submillimeter wave oscillator, array antenna and cavity resonator - Google Patents

Abstract

An object of the present invention is to realize a small and high-power submillimeter wave oscillator that can be easily and inexpensively manufactured.
A substrate 2 having a plurality of through-holes 1 provided at intervals corresponding to one or almost one wavelength of an oscillation wavelength in a submillimeter wave band, and a plurality of conductive layers provided in the plurality of through-holes 1. Cavities 3 made of a conductive material, a plurality of negative resistance elements 4 electrically connected to each of the plurality of cavity resonators 3, and a bias line electrically connected to the plurality of negative resistance elements 4 5.
[Selection] Figure 1

Description

  The present invention relates to a submillimeter wave oscillator, an array antenna, and a cavity resonator that can be used in, for example, imaging and a high-speed communication system and operate in a submillimeter wave band.

Conventionally, as an oscillator, (1) a configuration using a Fabry-Perot resonator, (2) a configuration in which a metal film or a semiconductor film is periodically formed on a substrate (for example, Patent Document 1), (3) a diode, for example, A configuration using a negative resistance element and a waveguide (for example, see FIG. 4 of Patent Document 2) has been reported.
Further, in the microwave band oscillator, the oscillation frequency can be adjusted by adjusting the distance between the negative resistance element and the short stub in the configuration of the above (3).

Non-Patent Document 1 describes that, in an oscillator using two Gunn diodes, an output equal to the sum of the specific outputs of the elements can be obtained by optimizing the distance between the elements.
Japanese Patent No. 2728200 Japanese Patent Laid-Open No. 1-272301 Saga et al., “Gun Diode Multi-Element Oscillator Using HRRD Guide”, IEICE Technical Report, TECHNICAL REPORT OF IEICE, ED99-220, MW99-152, 1999-11

However, although the configuration (1) is configured by using a quasi-optical design method, the resonator length is large with respect to the wavelength, so that the configuration is weak against mechanical vibrations and is not easily radiated. There is a problem.
The configuration (2) has a problem that the oscillation frequency changes when the thickness or properties of the metal film or semiconductor film changes.

  The configuration of (3) has good heat dissipation and is a technique that has been often used in microwave band oscillators. However, sub-millimeter wave oscillators have short wavelengths, making assembly difficult and increasing the cost of assembly. There is a problem of end. For example, in order to set the oscillation frequency to 300 GHz, the resonator length (length corresponding to half of the oscillation wavelength) is shortened to about 0.5 mm. Furthermore, in order to set the oscillation frequency to a desired frequency in the terahertz band, it is necessary to adjust the resonator length to about a few tens of μm. For this reason, assembling is difficult and the cost for assembling becomes high.

  In the configuration (3), for example, a negative resistance element (semiconductor element) such as a diode generally has a problem in that the oscillation output decreases because the amplification degree decreases as the frequency increases. Furthermore, since a waveguide is used, it is difficult to reduce the size. For this reason, a small and high-power submillimeter wave oscillator could not be realized with an oscillator having such a structure.

  The present invention has been devised in view of such problems, and an object of the present invention is to provide a small, high-power submillimeter wave oscillator that can be manufactured easily and inexpensively. Another object of the present invention is to provide an array antenna that can be manufactured easily and inexpensively and has an improved antenna gain. Furthermore, it aims at providing the cavity resonator which can be manufactured easily and cheaply.

  For this reason, the submillimeter wave band oscillator of the present invention includes a substrate having a plurality of through holes provided at intervals corresponding to one or almost one wavelength of the submillimeter wave band oscillation wavelength, and a plurality of through holes. A plurality of conductive cavity resonators, a plurality of negative resistance elements electrically connected to each of the plurality of cavity resonators, and a bias electrically connected to the plurality of negative resistance elements It is characterized by comprising a track.

  The array antenna of the present invention includes a substrate having a plurality of through holes provided at intervals corresponding to one wavelength of the target wavelength or substantially one wavelength, and a plurality of through holes so as to protrude from the back surface of the substrate. A plurality of antenna elements constituted by bag-like conductive films provided on the inner peripheral surface, a feeder line provided on the surface of the substrate so as to electrically connect the plurality of antenna elements, and a back surface of the substrate And a grounding conductive pattern provided in a portion other than the portion where the antenna element is formed.

  In the cavity resonator of the present invention, a resist is applied to the back surface of a substrate having a plurality of through holes, a space portion connected to the through holes is formed in the resist, and a conductive film is formed on the inner peripheral surfaces of the through holes and the space portions. It is formed by doing.

Therefore, according to the submillimeter wave oscillator of the present invention, there is an advantage that a small and high output submillimeter wave oscillator can be realized easily and inexpensively.
Further, the array antenna of the present invention is advantageous in that it can be manufactured easily and inexpensively and the antenna gain can be improved.
Furthermore, according to the cavity resonator of the present invention, there is an advantage that a cavity resonator that can be manufactured easily and inexpensively can be realized.

Hereinafter, a submillimeter wave oscillator, an array antenna, and a cavity resonator according to embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
First, a submillimeter wave oscillator and a cavity resonator according to a first embodiment of the present invention will be described with reference to FIGS.

  The submillimeter wave oscillator according to the present embodiment includes a substrate having a plurality of through holes (through vias) 1 as shown in a schematic perspective view of FIG. 1A and a schematic plan view of FIG. 2, a plurality of metal (conductive material) cavity resonators 3 provided on the back side of the substrate 2 of the plurality of through-holes 1, and the plurality of cavity resonators 3, respectively. A plurality of negative resistance elements (for example, diodes) 4 and a bias line (bias supply line; power supply circuit) 5 electrically connected to the plurality of negative resistance elements 4 are provided. In FIG. 1A, reference numeral 7 denotes a resist (photosensitive resin).

The submillimeter wave oscillator can also be called a terahertz submillimeter wave oscillator (terahertz submillimeter wave signal generator) capable of outputting an electromagnetic wave having an oscillation frequency in the terahertz band, for example.
Here, the plurality of through holes 1 are provided at intervals corresponding to one or almost one wavelength of the oscillation wavelength of the submillimeter wave band. Further, the plurality of negative resistance elements 4 and the bias line 5 are all provided on the surface of the substrate 2.

The cavity resonator 3 is configured by a bag-like metal film (conductive film) 3A provided on the inner peripheral surface of the through hole 1 so as to protrude from the back surface of the substrate 2 as shown in FIG. Is done. The metal film 3A constituting the cavity resonator 3 is grounded.
Here, the resonator length of the cavity resonator 3 (the distance from the lowermost end of the inner peripheral surface of the bag-shaped metal film 3A to the position where the negative resistance element 4 is provided) is the oscillation wavelength of the submillimeter wave band. The length corresponds to half (1/2 wavelength) or almost half (approximately 1/2 wavelength).

In the present embodiment, as shown in FIG. 1A, a negative resistance element 4 is electrically connected to each of a plurality of cavity resonators 3 provided on one substrate 2, whereby one substrate A plurality of oscillation elements 6 having a submillimeter wave band oscillation wavelength are formed on 2. For this reason, this submillimeter wave band oscillator is also called a submillimeter wave band multi-element oscillator.
In the present embodiment, the plurality of oscillating elements 6 are arranged on the substrate 2 with an interval corresponding to one or almost one of the submillimeter wave band oscillation wavelengths. Thereby, when an oscillation element 6 oscillates, the adjacent oscillation element 6 is synchronized and oscillates in the same phase, and the power output from each oscillation element 6 is spatially synthesized (power synthesis). Although it is a small structure, it is possible to obtain a large power (high output oscillation power) as an oscillation output.

Next, the manufacturing method of the submillimeter wave band oscillator concerning this embodiment is explained.
First, the cavity resonator 3 constituting the present submillimeter wave oscillator is formed as follows.
First, as shown in the schematic plan view of FIG. 2A, a substrate 2 having a plurality of through holes 1 is prepared, and as shown in the schematic cross-sectional view of FIG. A resist (thick film resist) 7 is applied to the substrate.

Next, as shown in the schematic cross-sectional view of FIG. 2C, a space 8 that is continuous with the through hole 1 is formed in the resist 7 by, for example, etching. That is, the plurality of space portions 8 used for forming the plurality of bag-like metal films (conductive films) 3 </ b> A constituting the plurality of cavity resonators 3 are patterned into the resist 7.
Next, as shown in the schematic cross-sectional view of FIG. 2D, the metal film 3A is formed on the inner peripheral surface of the through hole 2 and the space 8 by, for example, any one of sputtering, vapor deposition, plating, or a combination thereof. To form a cavity resonator 3 made of a bag-like metal film (conductive film) 3A.

Here, although the resist 7 is left as it is, for example, as shown in FIG. 3, a metal film 3A is formed to form a cavity resonator 3 made of a bag-like metal film (conductive film) 3A. Thereafter, the resist 7 may be removed.
The cavity resonator 3 according to this embodiment has an advantage that it can be manufactured easily and inexpensively. In addition, the cavity resonator formed as described above has an advantage of being easy to radiate heat because of its large surface area.

Depending on the patterning conditions (for example, etching conditions) and the film formation conditions of the metal film 3A, the cavity resonator 3 whose resonator length is about half the oscillation wavelength of the submillimeter wave band may be formed. it can. For example, in order to set the oscillation frequency to 300 GHz to 10 THz, the resonator length of the cavity resonator 3 is about several 15 μm to 0.5 mm.
After the cavity resonator 3 is formed in this way, as shown in FIG. 2E, around the through hole 1 on the surface of the substrate 2 (surface opposite to the surface on which the cavity resonator 3 is formed). A negative resistance element 4 is provided, and a bias supply line 5 for the negative resistance element 4 is further provided as shown in FIG.

  Therefore, the submillimeter wave oscillator according to the present embodiment has an advantage that a small and high output submillimeter wave oscillator can be realized easily and inexpensively. In particular, since a plurality of cavity resonators 3 and a plurality of negative resistance elements 4 (solid oscillation elements) can be provided on one substrate 2 by a simple process, the cost can be reduced and practical. A submillimeter wave solid-state oscillator can be realized.

For example, as shown in the equivalent circuit of FIG. 4, reactance components such as varactor diodes (variable capacitance diodes) can be changed to the negative resistance elements 4 constituting the submillimeter wave oscillator according to the above-described embodiment. You may comprise so that an oscillation frequency can be made variable by connecting the element 9 in parallel.
Further, for example, as shown in FIG. 5, a metal material or a desired thermal conductivity is provided on the back side of the substrate 2 so as to be connected to the cavity resonator 3 constituting the submillimeter wave oscillator according to the above-described embodiment. A heat sink (heat radiating member; heat radiating element) 11 may be provided through a layer 10 made of a resin material. If the resist 7 used for forming the cavity resonator 3 has a desired thermal conductivity, the heat sink 11 may be provided via the resist 7. As a result, the heat generated by the negative resistance element 4 can be efficiently released to the heat sink 11 via the cavity resonator 3, and good heat dissipation can be obtained.

  Furthermore, in the above-described embodiment, the cavity formed by the bag-shaped metal film 3A constituting the cavity resonator 3 is filled with air. However, the present invention is not limited to this. For example, a dielectric material or a gas is used. It only has to be satisfied. Thereby, since the effective resonator length of the cavity resonator 3 can be increased and the resonance frequency can be lowered, the resonance frequency can be finely adjusted.

In the above-described embodiment, the cavity resonator 3 is formed by the bag-shaped metal film 3A. However, the present invention is not limited to this.
For example, the cavity resonator 3 may be configured by a MEMS (Micro Electro Mechanical Systems) switch 3B. For example, as shown in FIGS. 6A and 6B, the cavity resonator 3 can be constituted by a MEMS switch 3B and a metal film 3C formed on the inner peripheral surface of the through hole 1 of the substrate 2. .

  Here, as shown in FIG. 6B [partial enlarged view of part A of FIG. 6A], the MEMS switch 3B includes a pair of disk-shaped metal films 3Ba and a pair that supports the disk-shaped metal films 3Ba. The metal film 3Bb and a bias terminal 3Bc connected to each of the metal films 3Bb are configured. For this reason, a cavity resonance made of a conductive material comprising a disk-shaped metal film (conductive film) 3Ba and a metal film (conductive film) 3C formed on the inner peripheral surface of the through hole 1 inside the through hole 1. A vessel 3 will be formed. In this case, an oscillation output is obtained from the back side of the substrate 2. The metal film 3C constituting the cavity resonator 3 is grounded. Although not shown, a bias supply line is connected to the bias terminal 3Bc.

Here, the thickness of the substrate 2 is set to about half the oscillation wavelength of the submillimeter wave band, and the position of the disk-shaped metal film 3 is set to the lowest position of the through hole 1 so that the resonator length is submillimeter. A cavity resonator 3 having a length about half the oscillation wavelength of the waveband is formed.
In this case, since the bias terminal of the MEMS switch 3B is provided around the through hole 1 on the front surface side of the substrate 2, the negative resistance element 4 and the bias supply line (not shown) are provided on the back surface of the substrate 2. Will be provided on the side.

  Thus, by configuring the cavity resonator 3 with the MEMS switch 3B, the position of the disk-shaped metal film 3Ba constituting the MEMS switch 3B is moved up and down as shown by the arrows in FIG. By moving the disk-shaped metal film 3Ba up and down along the inner peripheral surface of the through hole 1 [see FIG. 6A], the resonator length of the cavity resonator 3 can be changed. Thus, the oscillation frequency can be made variable.

Further, the disk-shaped metal film 3Ba constituting the MEMS switch 3B is moved so that the lowermost position of the through hole 1 (the substrate back surface position; the resonator length is about a half wavelength) and the uppermost position of the through hole 1 Oscillation output can be turned ON / OFF by alternately positioning (substrate surface position; resonator length is zero), whereby amplitude modulation can be applied.
[Second Embodiment]
Next, an array antenna according to a second embodiment of the present invention will be described with reference to FIGS.

In the array antenna according to this embodiment, the configuration of the antenna element is the same as the configuration of the cavity resonator of the submillimeter wave band oscillator according to the first embodiment described above.
The array antenna includes a substrate 22 having a plurality of through holes (through vias) 21 and an inner periphery of the through hole 21 so as to protrude from the back surface of the substrate 22 as shown in the schematic cross-sectional view of FIG. A plurality of antenna elements 23 constituted by a bag-like metal film (conductive film) 23A provided on the surface, and a feed line provided on the surface of the substrate 22 so as to electrically connect the plurality of antenna elements 23 24.

Here, as shown in FIG. 7A, the plurality of through holes 21 are provided at intervals corresponding to one wavelength of the target wavelength or substantially one wavelength.
Here, the length of the antenna element 23 (the distance from the lowermost end of the inner peripheral surface of the bag-shaped metal film 23A to the back surface of the substrate on which the grounding metal pattern 25 is formed) is 1 for the target wavelength. / 4 wavelength or almost ¼ wavelength. Thereby, the antenna element 23 constituted by the bag-like metal film 23A functions as a quarter wavelength grounded antenna as shown in FIG.

  In this embodiment, as shown in the schematic plan views of FIGS. 7A and 7B, a plurality of antenna elements 23 (here, bag-shaped metal films 23A) provided on one substrate 22 are provided. A power supply line 24 formed on the surface of the substrate 22 is connected to each. 7A and 7C, a grounding conductive pattern (here, a metal pattern) is formed on a portion other than the portion where the antenna element 23 is formed on the back surface of the substrate 22. ) 25 is formed.

In the present embodiment, the plurality of antenna elements 23 are arranged on one substrate 22 with an interval corresponding to one wavelength of the target wavelength or substantially one wavelength. Thereby, since the electric power radiated in the same phase from the individual antenna elements 23 provided on the back side of the substrate 22 is spatially combined (power combining), the antenna gain can be improved while the structure is small. .
Next, a method for manufacturing the array antenna according to this embodiment will be described.

First, the antenna element 23 constituting the array antenna is formed as follows in the same manner as the cavity resonator of the first embodiment (see FIG. 2).
First, a resist (thick film resist) is applied to the back surface of the substrate 22 having a plurality of through holes 21.
Next, a space portion that continues to the through hole 21 is formed in the resist by, for example, etching. That is, a plurality of spaces used for forming a plurality of bag-like metal films (conductive films) 23A constituting a plurality of antenna elements 23 are patterned into a resist.

Next, a metal film (conductive film) 23A is formed on the inner peripheral surface of the through hole 21 and the space portion by, for example, sputtering, vapor deposition, plating, or a combination thereof, and a bag-shaped metal film ( An antenna element 23 made of conductive film 23A is formed.
Note that the antenna element 23 is formed so that the length of the antenna element 23 is about ¼ of the target wavelength depending on the patterning conditions (for example, etching conditions) and the film formation conditions of the metal film 23A. Can do.

  After the antenna element 23 is formed in this way and the resist is removed, as shown in FIG. 7B, the through hole 21 on the surface of the substrate 22 (the surface opposite to the surface on which the antenna element 23 is formed). A feed line 24 (signal line) is provided so as to connect between the antenna elements 23 (between the antenna elements 23). Further, as shown in FIG. 7C, a grounding conductive pattern (here, a metal pattern) 25 is provided in a portion other than the portion where the antenna element 23 is formed on the back surface of the substrate 22. Thereby, an array antenna including a plurality of antenna elements 23 (¼ wavelength grounded antennas) is manufactured.

Therefore, the array antenna according to the present embodiment has advantages that it can be manufactured easily and inexpensively and the antenna gain can be improved.
In addition, as shown in FIG. 8, you may provide the phase shifter 27 which controls a phase in the middle of the feeder 24 which connects between the some antenna elements 23 which comprise the above-mentioned array antenna. Thereby, the phase of the electromagnetic field fed to each antenna 23 can be changed, and the direction (radiation direction) of the main beam radiated from the antenna 23 can be changed.
[Others]
The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

(Appendix 1)
A substrate having a plurality of through-holes provided at an interval corresponding to one or almost one wavelength of the oscillation wavelength of the submillimeter wave band;
A plurality of conductive resonator cavities provided in the plurality of through holes;
A plurality of negative resistance elements electrically connected to each of the plurality of cavity resonators;
A submillimeter wave band oscillator comprising a bias line electrically connected to the plurality of negative resistance elements.

(Appendix 2)
The cavity resonator applies a resist to the back surface of the substrate, forms a space portion connected to the through hole in the resist, and forms a conductive film on the inner peripheral surface of the through hole and the space portion. The submillimeter wave band oscillator according to appendix 1, wherein the submillimeter wave band oscillator is formed.
(Appendix 3)
The submillimeter wave band oscillator according to appendix 1, wherein the cavity resonator is constituted by a bag-like conductive film provided on an inner peripheral surface of the through hole so as to protrude from a back surface of the substrate.

(Appendix 4)
The submillimeter wave band oscillator according to any one of appendices 1 to 3, further comprising a reactance element connected in parallel to the negative resistance element.
(Appendix 5)
The submillimeter wave band oscillator according to any one of appendices 1 to 4, further comprising a heat radiating member provided on the back side of the substrate via a metal material or a resin material having a desired thermal conductivity. .

(Appendix 6)
The submillimeter wave oscillator according to appendix 1, wherein the cavity resonator is configured by a MEMS switch formed inside the through hole.
(Appendix 7)
The submillimeter wave band oscillator according to any one of appendices 1 to 6, wherein a cavity constituting the cavity resonator is filled with a dielectric material or a gas.

(Appendix 8)
A substrate having a plurality of through-holes provided at intervals corresponding to one or almost one wavelength of the target wavelength;
A plurality of antenna elements constituted by bag-like conductive films provided on the inner peripheral surfaces of the plurality of through holes so as to protrude from the back surface of the substrate;
A feed line provided on the surface of the substrate so as to electrically connect the plurality of antenna elements;
An array antenna comprising: a grounding conductive pattern provided on a portion of the back surface of the substrate other than the portion where the antenna element is formed.

(Appendix 9)
The antenna element coats a resist on the back surface of the substrate, forms a space portion connected to the through hole in the resist, forms a conductive film on the inner surface of the through hole and the space portion, and forms the resist. The array antenna according to claim 8, wherein the array antenna is formed by removing the antenna.

(Appendix 10)
The array antenna according to appendix 8 or 9, further comprising a phase shifter provided in the middle of the feeder line connecting the plurality of antenna elements and controlling the phase.
(Appendix 11)
Formed by applying a resist to the back surface of a substrate having a plurality of through holes, forming a space portion connected to the through hole in the resist, and forming a conductive film on the inner peripheral surface of the through hole and the space portion. A cavity resonator, wherein:

(Appendix 12)
A resist is applied to the back surface of a substrate having a plurality of through-holes, a space portion connected to the through-holes is formed in the resist, and a conductive film is formed on the inner peripheral surface of the through-holes and the space portions. A method for manufacturing a cavity resonator, characterized by manufacturing a resonator.

(A), (B) is a schematic diagram which shows the structure of the submillimeter wave band oscillator concerning 1st Embodiment of this invention. (A)-(E) is a figure for demonstrating the manufacturing method of the submillimeter wave band oscillator concerning 1st Embodiment of this invention. It is a figure for demonstrating the other structural example of the submillimeter wave band oscillator concerning 1st Embodiment of this invention. It is a figure for demonstrating the modification of the submillimeter wave band oscillator concerning 1st Embodiment of this invention. It is a figure for demonstrating the other modification of the submillimeter wave band oscillator concerning 1st Embodiment of this invention. (A), (B) is a figure for demonstrating the other modification of the submillimeter wave band oscillator concerning 1st Embodiment of this invention. (A)-(D) are figures which show the structure of the array antenna concerning 2nd Embodiment of this invention. It is a figure for demonstrating the modification of the array antenna concerning 2nd Embodiment of this invention.

Explanation of symbols

1,21 Through-hole 2,22 Substrate 3 Cavity resonator 3A, 23A Metal film (conductive film)
3B MEMS switch 3Ba Disk-shaped metal film (conductive film)
3Bb metal film 3Bc bias terminal 3C metal film (conductive film)
4 Negative resistance element 5 Bias line (bias supply line; power supply circuit)
6 Oscillating element 7 Resist 8 Space 9 Reactance element 10 Layer made of metal material or resin material having desired thermal conductivity 11 Heat sink 23 Antenna element 24 Feed line 25 Conductive pattern for grounding (metal pattern)
27 Phaser

Claims (5)

A substrate having a plurality of through-holes provided at an interval corresponding to one or almost one wavelength of the oscillation wavelength of the submillimeter wave band;
A plurality of conductive resonator cavities provided in the plurality of through holes;
A plurality of negative resistance elements electrically connected to each of the plurality of cavity resonators;
A submillimeter wave band oscillator comprising a bias line electrically connected to the plurality of negative resistance elements.   The cavity resonator applies a resist to the back surface of the substrate, forms a space portion connected to the through hole in the resist, and forms a conductive film on the inner peripheral surface of the through hole and the space portion. The submillimeter wave band oscillator according to claim 1, wherein the submillimeter wave oscillator is formed.   The submillimeter wave oscillator according to claim 1, wherein the cavity resonator is configured by a MEMS switch formed inside the through hole. A substrate having a plurality of through-holes provided at intervals corresponding to one or almost one wavelength of the target wavelength;
A plurality of antenna elements constituted by bag-like conductive films provided on the inner peripheral surfaces of the plurality of through holes so as to protrude from the back surface of the substrate;
A feed line provided on the surface of the substrate so as to electrically connect the plurality of antenna elements;
An array antenna comprising: a grounding conductive pattern provided on a portion of the back surface of the substrate other than the portion where the antenna element is formed.   Formed by applying a resist to the back surface of a substrate having a plurality of through holes, forming a space portion connected to the through hole in the resist, and forming a conductive film on the inner peripheral surface of the through hole and the space portion. A cavity resonator, wherein:

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