JPH10313213A - Planar antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate matching and adjustment of a circuit, to simplify the manufacturing process, to reduce the cost, and further to improve the reliability by providing a connection part which connects a signal processing circuit, the planar antenna, and a signal processing circuit and prevents a parasitic component from being generated. SOLUTION: On a metallic film 12 provided on a substrate 11, a slot line 13 which increase in slot width in a tapered shape is formed and constitutes a tapered slot antenna 14. On the metallic film 12, the signal processing part 15 which processes a signal to be sent and a signal received by using the tapered slot antenna 14 and the circuit connection part 16 are formed. The circuit connection part 16 consists of a connection path (coplanar line for circuit connection) which connects the signal processing part 15 and tapered slot antenna 14 to each other, a balun for mode conversion to the coplanar line, a stub for impedance matching, a resistor, an inductor, a capacitor, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar antenna integrally formed with a high-frequency circuit, and more particularly, to a circuit antenna having a high degree of freedom in circuit matching and adjustment, reliability and functionality, and being manufactured at low cost. Regarding possible planar antennas.

[0002]

2. Description of the Related Art There has been proposed an MMIC integrated antenna in which a microwave and millimeter wave signal processing circuit represented by MMIC and a planar antenna are formed on the same substrate.

[0003] Here, the MMIC is formed by forming a mixer, a local oscillator, an amplifier, various filters, and the like on the same semiconductor substrate in addition to a microwave and millimeter wave signal processing circuit. It is possible to realize a high-performance and low-cost chip corresponding to each device such as mobile communication and multimedia. MMIC
Is capable of optimal circuit design in that it is formed integrally with active elements such as HEMT and passive elements such as capacitors and resistors.
Unnecessary parasitic inductors and the like can be minimized.

[0004] One of the planar antennas used for the MMIC integrated antenna is a tapered slot antenna. This tapered slot antenna
The slot line has a structure in which the slot width of the slot line becomes wider with an inclination (in a tapered shape), and radiates an electromagnetic wave in a direction parallel to the antenna surface (the traveling direction of the slot line). Since this tapered slot antenna has a structure similar to that of a slot line, it does not require a ground conductor on the back surface unlike a microstrip line, and can be easily integrated with a feeder line or a matching circuit having a uniplanar structure.

[0005] Further, metallic materials, mainly gold, are used for the antennas and the connection lines of active elements and passive elements when forming MMICs. Gold has a characteristic that it has a low resistance value and a small loss at high frequencies, and also has a characteristic that it is easy to mount an MMIC on a substrate by bonding or the like.

[0006] Then, a planar antenna and an MMIC are formed respectively, and M is formed on the planar antenna by bonding or the like.
The MIC is mounted to form an MMIC integrated antenna.

[0007]

SUMMARY OF THE INVENTION However, MMI
C allows an optimal circuit design in that the active element and the passive element are integrally formed, and can minimize the occurrence of unnecessary parasitic inductors and the like.
There has been a problem that the manufacturing cost of the MMIC itself increases with an increase in the number of manufacturing steps. To solve this problem,
By forming only passive elements on silicon using microfabrication technology and forming chips, and then mounting active elements such as transistors and mixers on the chips,
Although a manufacturing method for reducing the cost has been proposed, there is no change in forming a plurality of elements on the same chip.
Therefore, an increase in the length of the manufacturing process cannot be avoided, and as a result, this has been an obstacle to cost reduction.

In order to form a small MMIC-integrated antenna, it is necessary to reduce the size of the planar antenna itself. However, when the above-mentioned tapered slot antenna is employed as the planar antenna, it is necessary to reduce the size of the antenna. When the length or the width of the antenna aperture is reduced, the directivity is deteriorated. That is, in the case of a tapered slot antenna, directivity is degraded when miniaturization is prioritized, and miniaturization cannot be achieved when directivity is prioritized.

In order to form an MMIC-integrated antenna, the MMIC and the planar antenna are separately manufactured and then integrated by bonding or the like. There has been a problem that it fluctuates greatly due to variations, and it is difficult to construct a stable system in terms of manufacturing and characteristics. Therefore, the yield has deteriorated, resulting in an increase in cost.

[0010] Furthermore, because of the ease of connection in mounting, a metal material containing gold as a main component is used for the base metal, so that there is a problem that the cost increases. In particular, since most of the tapered slot antenna is formed using a metal material, the effect of cost increase is great.
Further, when an MMIC or the like is mounted on a tapered slot antenna based on a gold thin film, there is a problem that reliability and mounting stability are low in consideration of mounting strength.

The present invention has been made in view of the above, and in a planar antenna provided with a high-frequency circuit and an intermediate frequency processing circuit, simplification of circuit matching and adjustment, simplification of a manufacturing process, and cost reduction. The purpose is to further improve the reliability.

It is another object of the present invention to reduce the size of a tapered slot antenna and achieve high directivity, and to reduce the size of a planar antenna.

[0013]

According to a first aspect of the present invention, there is provided a planar antenna, wherein a slot line is formed on a metal film provided on a substrate made of a dielectric so that the slot width is tapered. In the planar antenna configured by forming, mounted on an arbitrary area of the planar antenna, a signal processing circuit that processes a signal transmitted and a signal received using the planar antenna, formed in the metal film, A connection unit for connecting the planar antenna and the signal processing circuit and preventing generation of a parasitic component.

According to a second aspect of the present invention, in the planar antenna according to the first aspect, the connecting portion is formed simultaneously with forming the slot line.

According to a third aspect of the present invention, there is provided the planar antenna according to the first aspect, wherein the tapered slot line comprises:

(Equation 3) (Where x is the position coordinate of the antenna in the radiation direction, a,
(b and c are arbitrary constants).

According to a fourth aspect of the present invention, there is provided the planar antenna according to the first aspect, wherein the tapered slot line is formed by:

(Equation 4) (Where x is the position coordinate of the antenna in the radiation direction, a,
(b and c are arbitrary constants).

According to a fifth aspect of the present invention, in the planar antenna according to the first aspect, the metal film has a corrugated structure at an end parallel to a traveling direction of the slot line.

The planar antenna according to claim 6 is the planar antenna according to claim 1 or 5, wherein the metal film is made of at least copper.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the planar antenna according to the present invention will be described in detail with reference to the accompanying drawings.

[First Embodiment] FIG. 1 is a perspective view showing a schematic configuration of a planar antenna according to a first embodiment. FIG.
The planar antenna 10 shown in FIG. 1 includes a substrate 11 and a metal film 12 provided on the substrate 11.

The substrate 11 is made of a dielectric material such as polyimide and has a thickness of 10 to 100 μm, preferably 50 μm.
And the dielectric constant is 3.6.

The metal film 12 is mainly composed of copper (it can be composed of zinc or the like), and has a thickness of 2 to 20 μm. A slot line 13 is formed in the metal film 12 so that the slot width expands in a tapered shape.
4 is constituted. The metal film 12 has a circuit connection unit 16 for connecting the signal processing unit 15 for processing a signal transmitted using the tapered slot antenna 14 and a received signal and the tapered slot antenna 14 to enable transmission and reception. Are formed.

FIG. 2 is a plan view of the planar antenna 10 shown in FIG. Here, the tapered slot antenna 14 will be described with reference to FIG. 2, but for convenience of description,
Illustration of the signal processing unit 15 and the circuit connection unit 16 is omitted.

As described above, the tapered slot antenna 14 is designed so that the slot width is tapered.
It is constituted by forming the slot line 13 in the metal film 12. In this tapered slot antenna 14, the width of the antenna opening 17, which is a portion where the width of the slot line 13 is tapered, is 5 mm, the antenna length is 20 mm, and the width of the slot line 13 other than the antenna opening 17 is 50 μm. .

The tapered slot antenna 14
As the tapered shape of the slot line 13 of

(Equation 5) (Where x is the position coordinate of the antenna in the radiation direction, a,
(b and c are arbitrary constants).

As described above, by setting the tapered shape of the slot line 13 to the shape defined by the above equation (1), the planar antenna 10 having high directivity can be obtained even when the antenna length is shortened. Can be.

Also, instead of the above equation (1), the tapered shape of the slot line 13 is

(Equation 6) (Where x is the position coordinate of the antenna in the radiation direction, a,
b and c may be arbitrary constants). Also in the case of Expression (2), the planar antenna 10 having a short antenna length and high directivity can be obtained.

Returning to FIG. 1, the signal processing section 15 and the connection circuit section 16 will be described. The signal processing unit 15
It comprises a high frequency circuit and an intermediate frequency circuit for processing signals transmitted and received using the tapered slot antenna 14. The signal processing unit 15 is obtained by integrating a high-frequency circuit and an intermediate frequency circuit into a chip or separately forming them into a chip, and is mounted on an arbitrary region on the metal film 12 by soldering.

The circuit connection section 16 connects the signal processing section 15 and the tapered slot antenna 14 to enable signal transmission and reception (coplanar line for circuit connection), a balun for mode conversion to a coplanar line, A stub for impedance matching, a resistor, an inductor, a capacitor, and the like are formed on the metal film 12. When the high-frequency circuit and the intermediate frequency circuit are separately formed into chips, the connection path includes a connection path for connecting them.

In the circuit connecting portion 16, the resistors, inductors, capacitors, etc. are formed for the purpose of preventing the generation of parasitic components associated with the connection of the high-frequency circuit and the intermediate frequency circuit in an extremely high frequency range of several tens of GHz. It is a thing. It is to be noted that all necessary elements such as a resistor, an inductor, and a capacitor may be formed on the metal film 12, or a part may be formed together with the high frequency circuit and the intermediate frequency circuit, and the other part may be formed on the metal film 12. May be formed. As described above, by providing an element for preventing generation of a parasitic component using the same material as that of the tapered slot antenna 14 outside the high frequency circuit and the intermediate frequency circuit, the high frequency circuit and the intermediate frequency circuit are integrated. As compared with the case where the metal film 12 is used instead of the conventional case, compared with the case where the metal film 12 is separately formed using another material, the degree of freedom of design can be increased and the high-frequency circuit can be formed. In addition, the number of manufacturing steps of the intermediate frequency circuit can be reduced, and the manufacturing cost can be reduced.

The planar antenna 10 having the above configuration is used, for example, in mobile communication equipment and small information terminals.

Next, a manufacturing process of the above-described planar antenna 10 will be described with reference to FIG.

For example, a polyimide film having a thickness of 50 μm
Is prepared, and a metal film 12 is formed on the prepared substrate 11.
To form a copper thin film having a thickness of 10 μm.

Then, a tapered slot antenna 14 having a shape based on the above formula (1) or (2) is formed on the formed metal film 12 by photolithography.
After forming a pattern of a circuit connecting portion 16 such as a circuit connecting coplanar line, an impedance matching stub, and a resistor based on a predetermined design dimension, a ferric chloride-based etchant is used. The metal film 12 by etching to form a tapered slot antenna 1
4 and a circuit connecting portion 16 are formed.

After that, the signal processing section 15 is solder-mounted to obtain the planar antenna 10 shown in FIG.

As described above, according to the planar antenna 10 of the first embodiment, the slot line 13 is formed in the metal film 12 provided on the dielectric substrate 11 so that the slot width is tapered. And a signal processing unit 15 provided on the substrate 11 and configured to process a signal transmitted using the tapered slot antenna 14 and a received signal.
And a circuit connection unit 16 formed on the metal film 12 and connected to the tapered slot antenna 14 and the signal processing unit 15 to enable transmission and reception of signals and to prevent generation of a parasitic component. The manufacturing process can be simplified and the cost can be reduced.

In an extremely high frequency range such as several tens of GHz, generation of unnecessary inductors and capacitors (parasitic components) due to circuit connection of the signal processing unit 15 cannot be avoided. Then, instead of the signal processing unit 15, elements such as a resistor, an inductor, and a capacitor for preventing generation of a parasitic component are formed in the metal film 12, so that not only simplification of the manufacturing process but also circuit matching and adjustment are performed. A planar antenna that is easy and has a high degree of design freedom can be obtained.

Further, the tapered slot antenna 14
Since the taper shape of (1) is a shape defined by the formula (1) or (2), high directivity and miniaturization can be achieved at the same time, and manufacturing can be facilitated.

Considering that the high-frequency circuit and the intermediate frequency circuit can be easily mounted using the metal film 12 of the planar antenna 10, the connection by the coplanar line is considered to be promising. It is needless to say that a connection can be made by a microstrip line using a metal material such as copper or a metal plate in a form in which the strength in mounting is secured at the bottom of the device.

[Second Embodiment] In a second embodiment, a configuration will be described in which the tapered slot antenna 14 is further downsized by maintaining a high directivity and reducing the antenna width.

FIG. 3 is a plan view of the planar antenna according to the second embodiment. In FIG. 3, the same components as those shown in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof will be omitted. Further, in the second embodiment, only the tapered slot antenna 14 will be described, so that the signal processing unit 15 and the circuit connection unit 16 are not shown.

The planar antenna 10 shown in FIG. 3 has a corrugated structure 30 formed by periodically removing the end of the metal film 12 parallel to the radiation direction of the electromagnetic wave of the tapered slot antenna 14 into a rectangular shape. ing. The corrugated structure 30 is formed simultaneously with the formation of the tapered slot antenna 14 by the method described in the first embodiment.

In the planar antenna 10 of the second embodiment, the design frequency of the tapered slot antenna 14 is 6
0 GHz, antenna length 20 mm, antenna opening 17
Is 5 mm, and the distances D1 and D2 between the end of the antenna opening 17 and the antenna end are each 2.5 mm. Further, the corrugated structure 30 is formed by removing the metal film 12 into a 2 mm × 1 mm rectangular shape at a cycle of 4 mm.

FIG. 4 is an enlarged view of the area A in FIG.
Hereinafter, a mechanism for achieving miniaturization while providing the directivity of the tapered slot antenna 14 by providing the corrugated structure 30 on the metal film 12 of the planar antenna 10 will be described with reference to FIG.

As described above, the corrugated structure 3
Numeral 0 is formed at the end of the metal film 12 parallel to the radiation direction of the electromagnetic wave of the tapered slot antenna 14, and is formed by periodically removing the metal film 12 on the substrate 11 into a rectangular shape. Things. In FIG.
Reference numeral 30a denotes a region where the metal film 12 formed on the substrate 11 is periodically removed in a rectangular shape, and only the substrate 11 exists in this region.

In the tapered slot antenna 14, the electromagnetic wave changes to a mode of propagating in free space while propagating through the slot line 13, and is radiated to the outside. In the process, to compensate for the discontinuity of the mode from the slot line 13 to the free space, a surface wave mode transmitted on the surface of the substrate 11 is excited. Here, the antenna opening 17
If the distances D1 and D2 between the end of the antenna and the end of the antenna are sufficiently long, this effect can be neglected because the surface wave only propagates in the direction away from the antenna. However, when the distances D1 and D2 between the end of the antenna opening 17 and the end of the antenna are short, the surface wave is reflected at the end of the antenna, returns to the antenna, and propagates through the slot line 13 and free space again. Interacts with electromagnetic waves.

In FIG. 4, reference numeral 40 denotes a surface wave generated in the antenna section, and this surface wave is reflected at the ends 30b and 30c of the corrugated structure 30. The surface waves reflected at the ends 30b and 30c of the corrugated structure 30 are propagated again toward the antenna, but the surface waves cancel each other out due to the action of the corrugated structure 30 and return to the antenna. The intensity of the traveling surface wave is weakened. That is, by providing the corrugated structure 30 at the end of the metal film 12, irregularities are formed at the end of the metal film 12. As a result, since the positions of the end portions 30b and 30c of the corrugated structure 30 shown in FIG. 4 are different, the positions where the surface waves from the antenna unit are reflected are different. Therefore, the end 30 of the corrugated structure 30
The surface waves reflected by b and 30c are out of phase with each other due to the difference in the optical path length, and cancel each other out, so that the intensity is weakened.

Therefore, even when the distances D1 and D2 between the end of the antenna opening 17 and the antenna end are shortened, the provision of the corrugated structure 30 allows
The characteristics of the tapered slot antenna 14 can be prevented from deteriorating.

Next, the measurement result of the directivity of the tapered slot antenna 14 of the planar antenna 10 according to the second embodiment will be described in comparison with a tapered slot antenna having no corrugated structure 30.

FIGS. 5A and 5B show the directivity of the tapered slot antenna 14 shown in FIG.
FIG. 5A shows the measurement result for the E-plane, and FIG. 5B shows the measurement result for the H-plane. 6A and FIG.
(B) shows the tapered slot antenna 14 shown in FIG.
6A and 6B show the results obtained by measuring the directivity at 60 GHz without having the corrugated structure 30. FIG. 6A shows the measurement results for the E-plane, and FIG. The measurement results for the H plane are shown.

6 (a) and 6 (b) show the measurement results of the tapered slot antenna without the corrugated structure 30, and the directivity main lobe on the E-plane is broken to increase the side lobe level. It can be seen that there is a problem that the directivity of the H plane becomes slightly broad. However, it can be seen from FIGS. 5A and 5B that the above problem is clearly improved in the tapered slot antenna 14 having the corrugated structure 30.
The result showing the effectiveness of providing the corrugated structure 30 was obtained.

As described above, according to the planar antenna 10 of the second embodiment, since the corrugated structure portions 30 are provided at the ends of the metal film 12 parallel to the radiation direction of the electromagnetic wave of the tapered slot antenna 14, even if the antenna aperture Even when the distances D1 and D2 between the end of the portion 17 and the antenna end are reduced to reduce the size, the strength of the surface wave reflected at the antenna end can be reduced, and the tapered slot antenna can be used. 14 can be prevented from deteriorating.

[0053]

As described above, according to the planar antenna of the present invention (claim 1), the slot line is formed in the metal film provided on the substrate made of a dielectric so that the slot width is tapered. And a signal processing circuit that is mounted on an arbitrary area of the planar antenna, processes a signal transmitted using the planar antenna and processes a received signal, and a planar antenna formed on a metal film. And the signal processing circuit,
Since a connection portion for preventing generation of a parasitic component is provided, it is possible to facilitate circuit matching and adjustment, simplify a manufacturing process, reduce cost, and further improve reliability.

The planar antenna according to the present invention (claim 2)
According to the planar antenna according to the first aspect, since the connection portion is formed at the same time when the slot line is formed, the number of manufacturing steps can be reduced, and
This can greatly contribute to improving the yield.

Further, the planar antenna of the present invention (claim 3)
According to the planar antenna according to claim 1, the slot line formed in a tapered shape is:

(Equation 7) (Where x is the position coordinate of the antenna in the radiation direction, a,
b and c are arbitrary constants).
The planar antenna can be reduced in size while maintaining high directivity.

The planar antenna according to the present invention (claim 4)
According to the planar antenna according to claim 1, the slot line formed in a tapered shape is:

(Equation 8) (Where x is the position coordinate of the antenna in the radiation direction, a,
b and c are arbitrary constants).
It is possible to reduce the size of the entire planar antenna while maintaining high directivity.

Further, the planar antenna of the present invention (Claim 5)
According to the flat antenna according to claim 1, since the metal film has a corrugated structure at each end parallel to the traveling direction of the slot line, the distance between the end of the antenna opening and the antenna end is set. , The strength of the surface wave reflected at the end of the antenna can be reduced, and the directivity of the planar antenna can be prevented from deteriorating.

Further, according to the planar antenna of the present invention (claim 6), in the planar antenna according to claim 1 or 5, since the metal film is made of at least copper, the workability is excellent and the mass productivity is excellent. Thus, a highly reliable planar antenna can be obtained at low cost. Gold, which has been conventionally used as a metal film, has poor adhesion to a dielectric substrate and has a problem in reliability. However, the use of copper solves the problem in the case of gold.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic configuration of a planar antenna according to a first embodiment.

FIG. 2 is a plan view of the planar antenna shown in FIG.

FIG. 3 is a plan view of a planar antenna according to a second embodiment.

FIG. 4 is an enlarged view of a region A in FIG.

5A and 5B show the results of measuring the directivity of the tapered slot antenna shown in FIG. 3 at 60 GHz, where FIG. 5A shows the measurement results for the E plane and FIG. 5B shows the measurement results for the H plane. .

6A and 6B are results obtained by measuring the directivity of a tapered slot antenna having the same size as the tapered slot antenna shown in FIG. 3 and having no corrugated structure at 60 GHz, and FIG. (B) shows the measurement results for the H plane.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Planar antenna 11 Substrate 12 Metal film 13 Slot line 14 Tapered slot antenna 15 Signal processing part 16 Circuit connection part 17 Antenna opening part 30 Corrugated structure part

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yutaka Yoneda 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company, Ltd.

Claims (6)

[Claims] 1. A planar antenna formed by forming a slot line in a metal film provided on a substrate made of a dielectric so that a slot width is tapered, wherein the slot line is formed in an arbitrary region of the planar antenna. A signal processing circuit that is mounted and processes a signal transmitted and a signal received using the planar antenna, and is formed on the metal film, connects the planar antenna and the signal processing circuit, and generates a parasitic component. A planar antenna, comprising: 2. The planar antenna according to claim 1, wherein the connecting portion is formed simultaneously with forming the slot line. 3. The tapered slot line has the following formula: (Where x is the position coordinate of the antenna in the radiation direction, a,
2. The planar antenna according to claim 1, wherein the planar antenna has a shape defined by (b and c are arbitrary constants). 3. 4. The tapered slot line comprises: (Where x is the position coordinate of the antenna in the radiation direction, a,
2. The planar antenna according to claim 1, wherein the planar antenna has a shape defined by (b and c are arbitrary constants). 3. 5. The planar antenna according to claim 1, wherein each of the metal films has a corrugated structure at an end parallel to a traveling direction of the slot line. 6. The planar antenna according to claim 1, wherein the metal film is made of at least copper.