JPH08335827A - Antenna device - Google Patents

Abstract

PURPOSE: To provide a compact and thin antenna device which can be easily produced and can reduce the influence that is caused by the undesired radiation generated from a feeder line and given to an antenna radiation field by using a coplanar line having large thickness of a ground conductor as the feeder line of a radiation element. CONSTITUTION: A dielectric film 20 is formed on a semiconductor or dielectric substrate 10, and a ground conductor film 41 is formed on the film 20. A slot 40 serving as a radiation element is formed at a part of the film 41, and a reflector 42 is placed on the back of the substrate 10. A coplanar line 30 serving as a feeder line consists of a strip-shaped center conductor 31 which is formed between the substrate 10 and the film 41 as if it crossed the slot 40 and the strip-shaped ground conductors 32 and 33 which hold the conductor 31 between them excluding the lower part of the slot 40 and have larger thickness than the conductor 31. As both conductors 32 and 33 have sufficient thickness, the characteristic of the line 30 is decided by the line width of the conductor 31 and the gap secured between both conductors 31 and 32 (33).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna device composed of a radiation element for transmitting and receiving a high frequency signal of, for example, 1 GHz or more and a feeding line for transmitting the high frequency signal.

[0002]

2. Description of the Related Art FIG. 9 shows the configuration of a conventional antenna device. This configuration is based on the literature ("Characterization of a Monoli
thic Slot Antenna Usingan Electro-Optic Sampling T
echnique ", IEEE, Microwave and Guided WaveLetter
s, Vol.4, No.12, pp.414-416 (Dec. 1994)).

In the figure, on a semiconductor substrate 100, a coplanar line 101 serving as a feed line and a slot 102 serving as a radiating element are formed to constitute an antenna device. The signal propagating in the coplanar line 101 is transmitted to the slot 102 via the air bridge 103, excites the slot 102 which is a kind of resonator, and radiates a radio wave in space.

This antenna device is a gallium arsenide (GaA) used in a monolithic microwave integrated circuit (MMIC).
s) Since the feed line and the radiating element are formed on a semiconductor substrate such as silicon (Si), it has a feature that it can be formed with high density and reproducibility including an electronic circuit in a semiconductor process. Moreover, this antenna form is suitable for activation such as an active phased array or an adaptive array, which can arbitrarily re-form beam forming or realize a high-performance antenna for suppressing / removing interference waves. Also, due to the high dielectric constant of the semiconductor substrate, downsizing is easy,
Since the feeder line can be shortened by disposing the electronic circuit and the radiating element close to each other, the transmission loss of the high frequency signal by the feeder line is small. Furthermore, since the radiating element is configured to be co-planarly fed, it is possible to perform on-wear evaluation of this antenna device, which is effective in shortening the development period and reducing costs.
It is also easy to mount on a package.

Many antenna devices based on the coplanar power feeding method have been developed. The typical one is shown in FIG.
Shown in (a) and (b). The antenna device shown in FIG. 10A has a configuration in which a microstrip line 111 is used as a feed line and a microstrip antenna 112 is used as a radiating element. The antenna device shown in FIG. 10B has a configuration in which the slot line 113 is used as a feed line and the slot antenna 114 is used as a radiating element. Such an antenna device is also suitable for activation by using a semiconductor substrate and can be evaluated on-wear.

[0006]

By the way, in the conventional antenna device shown in FIGS. 9 and 10, the leakage of the electromagnetic field from the feeding line adversely affects the radiation field of the antenna. In particular, when a mismatch occurs between the radiating element and the feed line at the feed point, a standing wave is generated in the feed line, and the influence of unnecessary radiation from the feed line on the antenna radiation field is a serious problem. Further, when the electronic circuit is integrated, it is necessary to separate the radiating element and the electronic circuit from each other in order to prevent electromagnetic recombination. As a result, the size of the entire antenna device is increased, and the degree of freedom in the wiring layout of the electronic circuit is reduced.

It is an object of the present invention to provide an antenna device which is small in size, thin in thickness, and easy to manufacture, because the influence of unwanted radiation from a feeding line on an antenna radiation field can be reduced.

[0008]

In the antenna device of the present invention, a first dielectric film is formed on a substrate made of a semiconductor or a dielectric, and a ground conductor film and a first radiation film are formed on the first dielectric film. A slot serving as an element is formed, a coplanar line serving as a feed line of the first radiating element is formed in the first dielectric film, and a strip-shaped ground conductor of the coplanar line is connected to a ground conductor film to form a ground conductor. Is set thicker than the strip-shaped center conductor (claim 1).

Further, the ground conductor of the coplanar line is formed so as to penetrate the first dielectric film (claim 2). Further, the bottom portion of the ground conductor sandwiching the center conductor of the coplanar line is connected via the conductor (claim 3). Further, a slot to be the first radiating element is formed so as to penetrate the first dielectric film (claim 4).

Further, one end of the slot which becomes the first radiating element is formed in a tapered shape, and the tapered slot forms an end fire antenna (claim 5). Also,
A reflector made of a metal conductor is arranged on the side of the substrate on which the first radiating element is not formed, with a dielectric or a gap therebetween. A second dielectric film is formed on the ground conductor film, and a second radiating element is formed on the second dielectric film (claim 7).

Further, the above plurality of antenna devices are formed on the same substrate or on the second dielectric film (claim 8). In addition, one end of the coplanar line is formed as a terminating open stub having a quarter wavelength from the position where the slot intersects with the coplanar line (claim 9).

[0012]

In the antenna device of the present invention, since the coplanar line having the thick ground conductor is used as the feed line of the radiating element, the effect of shielding the electromagnetic field from the feed line can be enhanced. As a result, it is possible to reduce the influence of unnecessary radiation from the feed line on the antenna radiation field as compared with the conventional configuration.

The operation of the antenna device according to claims 2 to 6, 8 and 9 will be described in the section of the embodiment. In the antenna device according to the seventh aspect, the second radiating element (microstrip antenna) can be electromagnetically coupled and excited via the first radiating element.

[0014]

【Example】

(First Embodiment) FIG. 1 shows the configuration of a first embodiment of the antenna device of the present invention. FIG. 1 (a) is a perspective view, and FIG.
FIG. 1C is a sectional view taken along the line AA ′ and the line BB ′ of FIG.

In the figure, a dielectric film 20 is formed on a substrate 10 made of a semiconductor or a dielectric, a ground conductor film 41 is formed on the dielectric film 20, and a slot 40 serving as a radiating element is formed in a part thereof. On the other hand, the reflection plate 42 is arranged on the opposite surface of the substrate 10. Coplanar line 30 that serves as a power supply line
Is a slot 40 between the substrate 10 and the ground conductor film 41.
Strip-shaped central conductor 31 formed so as to traverse
And strip-shaped ground conductors 32 and 33 formed so as to sandwich the central conductor 31 except for the lower portion of the slot 40. The ground conductors 32 and 33 are the ground conductor film 4
1 and the dielectric film 20 is penetrated between the substrate 10 and the ground conductor film 41, and the end portion thereof is connected. here,
Since the ground conductors 32 and 33 are sufficiently thick, the line characteristics (impedance, etc.) are determined by the line width of the center conductor 31 and the gap between the center conductor 31 and the ground conductor 32 (33), and the coplanar line (or ground). It operates as a coplanar line with a conductor). Reference numeral 60 is an electronic circuit.

Next, the operating principle will be described. The signal propagating through the coplanar line 30 is provided with a quarter-wave end open stub 34 as shown in FIG. 1 (c).
The power is converted from the coplanar mode (unbalanced mode) to the slot mode (balanced mode) and transmitted to the slot 40. The signal excites the slot 40 and a radio wave is radiated into the space. Here, since the reflection plate 42 is formed at a distance of about 1/4 wavelength from the slot 40, the radio wave is emitted from FIG.
It is radiated only upward in (b) and (c).

The ground conductors 32 and 33 of the coplanar line 30 of this embodiment may penetrate the dielectric film 20 as shown in FIG. 1 or may be non-penetrated if the thickness is sufficient. Further, the center conductor 31 of the coplanar line 30 may be formed not only at a position distant from the substrate 10 but also on the substrate 10. Further, instead of using the stub, the central conductor 31 of the coplanar line 30 and the slot 40 may be directly connected to each other by using a through hole in the power feeding portion for excitation. Further, although the rectangular slot 40 is shown as the radiating element in this embodiment, the slot 40 may have any shape as shown in FIGS. 2 (a) and 2 (b), for example. Although an example with one element is shown here, the same configuration can be applied to an array antenna having a multi-element array.

(Second Embodiment) FIG. 3 shows the configuration of a second embodiment of the antenna device of the present invention. 3 (a) is a perspective view, and FIG. 3 (b) is a sectional view taken along the line AA 'in FIG. 3 (a). The feature of this embodiment is that in the configuration of the first embodiment, the ground conductor 3 is provided below the center conductor 31 via the conductor 35.
It is in the place where 2 and 33 are connected.

The operating principle of this embodiment is the same as that of the first embodiment, and the same effect as that of the first embodiment can be obtained. In the present embodiment, the conductor 35 blocks the leakage of the electromagnetic field from the coplanar line 30 toward the substrate 10, so that the antenna device of the present embodiment can be operated as a bidirectional antenna. (Third Embodiment) FIG. 4 shows the configuration of a third embodiment of the antenna device of the present invention. Fig. 4 (a) is a perspective view, and Fig. 4 (b)
4 is a perspective view seen from the direction of arrow B with the line AA ′ of FIG.

The feature of this embodiment is that, in the structure of the first embodiment, the slot 40, which is a radiating element, is formed between the substrate 10 and the ground conductor film 41 so as to penetrate the dielectric film 20. . The operation principle of this embodiment is the same as that of the first embodiment, and the same effect as that of the first embodiment can be obtained. In this embodiment, since the slot 40 is formed on the substrate 10 having a high dielectric constant, the equivalent dielectric constant is increased and the antenna device can be downsized. In addition, since the through-holes 40 reduce the coupling with the electronic circuit and other power supply lines, the degree of integration of the antenna device can be increased.

(Fourth Embodiment) FIG. 5 shows the configuration of a fourth embodiment of the antenna device of the present invention. 5 (a) is a sectional view and FIG. 5 (b) is a top view. The same parts as those in the first embodiment are designated by the same reference numerals. The feature of this embodiment is that the rectangular slots 50 and 51 are formed above the terminated coplanar line 30 with a quarter wavelength interval and an angular difference of 90 degrees.

The operating principle of this embodiment is the same as that of the first embodiment, and the same effect as that of the first embodiment can be obtained. In this embodiment, a circular polarization slot antenna is composed of the two rectangular slots 50 and 51 that have a phase difference of 90 degrees electrically and spatially. Further, a circular polarization array antenna can be easily constructed by arranging a plurality of two slots as one set.

(Fifth Embodiment) FIG. 6 shows the configuration of a fifth embodiment of the antenna device of the present invention. 6A is a perspective view and FIG. 6B is a top view. The feature of this embodiment is that the first
The reflector 42 is removed from the configuration of the embodiment, and one end of the slot 40, which is a radiating element, is formed in a tapered shape.

In the configuration of this embodiment, the coplanar line 30
The signal propagating through is converted from the coplanar mode (unbalanced mode) to the slot mode (balanced mode) at the feeding section by providing the terminating open stub 34 of 1/4 wavelength as shown in FIG. 6 (b). It is transmitted to the slot 40. Also,
As shown in Fig. 6 (b), the quarter-wave termination stub 36
By providing, the signal transmitted to the slot 40 is transmitted only in the tapered direction. Here, by setting the tapered slot to about 1 wavelength, the radio wave is radiated from the tip of the tapered slot and operates as an end fire antenna.

Where λs is the wavelength in the coplanar line,
λ is the wavelength in the slot, and λ ₀ is the wavelength in free space. Also in this embodiment, the same effect as that of the first embodiment can be obtained. In addition, the antenna device in this embodiment is
Since it is an end-fire antenna and a unidirectional antenna, no reflector is required. Further, since the slot 40 is formed in a tapered shape and can be easily matched with the waveguide, it is suitable for a power combining antenna in a millimeter wave band that requires a large amount of power.

(Sixth Embodiment) FIG. 7 shows the configuration of a sixth embodiment of the antenna device of the present invention. FIG. 7 (a) is a perspective view and FIG. 7 (b) is a top view. The feature of this embodiment is that the first
In the configuration of the embodiment, the second dielectric film 70 is formed on the ground conductor film 41 and the slot 40, and the microstrip antenna 80 which is the second radiating element is formed on the second dielectric film 70. To do. The microstrip antenna 80 is electromagnetically coupled and excited via the slot 40 which is the first radiating element.

Also in this embodiment, the same effect as that of the first embodiment can be obtained. Furthermore, since the radiating element, the electronic circuit, and the feed line can be formed by being stacked, a small, thin, highly integrated antenna device that is easy to manufacture can be realized. In particular, it is effective in a relatively low frequency band in which the size of the radiating element is large for an electronic circuit. Further, since the microstrip antenna is used as the radiating element, it is possible to construct a unidirectional antenna device without providing a reflector.

In this embodiment, the circular microstrip antenna 80 is shown as the second radiating element, but other arbitrary shapes may be used. Further, as shown in FIG. 8, the terminals of the two slots 40 may be excited with a phase difference of 90 degrees, or the microstrip antenna 80 may be provided with a degenerate separation element to excite circular polarization. Although an example with one element is shown here, the same configuration can be applied to an array antenna having a multi-element array.

[0029]

As described above, in the antenna device of the present invention, the influence of the unnecessary radiation from the feeding line on the antenna radiation field can be reduced as compared with the conventional configuration. Further, since the coupling between the electronic circuit and the other power supply line adjacent to each other can be reduced, the degree of freedom in the circuit design and wiring layout of the electronic circuit can be increased. Further, by forming the electronic circuit, the feeding line, and the radiating element using the semiconductor process, it is possible to realize a small and thin antenna device which is easy to manufacture. further,
Since the radiating element is configured to be fed in the same plane, this antenna device can be evaluated on-wear, which is effective in shortening the development period and reducing the cost, and can be easily mounted on a package or the like.

Further, in the antenna device provided with the second radiating element (microstrip antenna) excited via the first radiating element, the radiating element has a large size for an electronic circuit even in a relatively low frequency band. , Small, thin,
High integration becomes easy. When a microstrip antenna is used as the radiating element, unidirectionality can be realized without providing a reflector or the like.

[Brief description of drawings]

FIG. 1 is a diagram showing the configuration of a first embodiment of an antenna device of the present invention.

FIG. 2 is a plan view showing a modification of the first embodiment.

FIG. 3 is a diagram showing the configuration of a second embodiment of the antenna device of the present invention.

FIG. 4 is a diagram showing the configuration of a third embodiment of the antenna device of the present invention.

FIG. 5 is a diagram showing the configuration of a fourth embodiment of the antenna device of the present invention.

FIG. 6 is a diagram showing the configuration of a fifth embodiment of the antenna device of the present invention.

FIG. 7 is a diagram showing the configuration of a sixth embodiment of the antenna device of the present invention.

FIG. 8 is a plan view showing a modification of the sixth embodiment.

FIG. 9 is a diagram showing a configuration of a conventional antenna device.

FIG. 10 is a diagram showing a configuration of a conventional antenna device using a coplanar power feeding method.

[Explanation of symbols]

 10 Semiconductor or Dielectric Substrate 20 Dielectric Film 30 Coplanar Line 31 Center Conductor 32, 33 Grounding Conductor 34 Termination Open Stub 35 Conductor 36 Termination Shorting Stub 40, 50, 51 Slot 41 Grounding Conductor Film 42 Reflector 60 Electronic Circuit 70 Dielectric Body film 80 Microstrip antenna 100 Semiconductor substrate 101 Coplanar line 102 Slot 103 Air bridge 111 Microstrip line 112 Microstrip antenna 113 Slot line 114 Slot antenna

Front Page Continuation (72) Inventor Kazuhiko Toyota 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (9)

[Claims] 1. A substrate made of a semiconductor or a dielectric, a first dielectric film formed on the substrate, a ground conductor film and a first radiating element formed on the first dielectric film. And a coplanar line serving as a feed line for the first radiating element formed in the first dielectric film, wherein a strip-shaped ground conductor of the coplanar line is connected to the ground conductor film. An antenna device, wherein the thickness of the ground conductor is set to be thicker than that of the strip-shaped center conductor. 2. The antenna device according to claim 1, wherein the ground conductor of the coplanar line is formed so as to penetrate through the first dielectric film. 3. The antenna device according to claim 1, wherein a bottom portion of a ground conductor sandwiching a center conductor of the coplanar line is connected via a conductor. 4. The antenna device according to claim 1, wherein a slot serving as a first radiating element is formed so as to penetrate the first dielectric film. 5. The antenna device according to any one of claims 1 to 4, wherein one end of a slot serving as a first radiating element is formed in a tapered shape, and the tapered slot forms an endfire antenna. An antenna device characterized by. 6. The antenna device according to any one of claims 1 to 4, wherein a reflection plate made of a metal conductor is arranged on a side of the substrate on which the first radiating element is not formed, via a dielectric or a gap. An antenna device characterized by being made. 7. The antenna device according to any one of claims 1 to 4, wherein a second dielectric film is formed on the ground conductor film, and the second radiating element is formed on the second dielectric film. An antenna device characterized by being formed. 8. An antenna device, wherein the plurality of antenna devices according to claim 1 are formed on the same substrate or on a second dielectric film. 9. The antenna device according to any one of claims 1 to 8, wherein one end of the coplanar line is configured as an open-ended stub having a quarter wavelength from a position where the slot intersects with the coplanar line. Antenna device.