JP3194468B2 - Microstrip antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna used for transmitting and receiving a radio signal in a microwave band to a millimeter wave band, a feed line for transmitting the radio signal, and a high-frequency circuit. In particular, the present invention relates to a microstrip antenna that is small in size, thin in thickness, and capable of integrally forming a plurality of antennas in different frequency bands. Examples of applications of the present invention include personal wireless devices such as gate cards and security cards, and AWA (ATM).
Wireless access), a mobile terminal, and the like. Due to the problem of fading and shadowing due to multipath, a high-speed wireless LAN in a premises where a multi-band system is proposed requires a small-sized wireless device that has a planar structure and is easy to mount. It is also applicable to small wireless devices.

[0002]

2. Description of the Related Art Microstrip antennas are small, light and thin, and have been applied in various fields as radar, mobile communication, and satellite communication antennas.
A microstrip antenna is an antenna most suitable for an active antenna. Here, the active antenna is an antenna in which an antenna element, a feed circuit, an active device or an active circuit are integrated on the same substrate,
This is effective for reducing the size, cost, and multifunctionality of the device.

FIG. 14A is a perspective view showing an example of a conventional microstrip antenna, and FIG.
FIG. 15 is a cross-sectional view taken along the line AA in FIG.
In these figures, reference numeral 102 denotes an antenna element, 101 denotes a ground conductor, and 100 denotes a dielectric film. The antenna element 102, the ground conductor 101, and the dielectric film 100 form a microstrip antenna 104.

[0004] Reference numeral 103 denotes a strip-shaped conductor.
The strip conductor 103, the ground conductor 101 and the dielectric film 100 constitute a microstrip line 105. The signal propagating through the microstrip line 105 is electromagnetically coupled to the antenna element 102 to excite the microstrip antenna 104. When a microstrip antenna 104, which is a type of resonator, is excited, a radio wave is emitted into space. However, in this microstrip antenna, since the microstrip line 105 serving as a feed line is formed in the radiation direction of the radio wave with respect to the ground conductor 101, "unnecessary radiation from the microstrip line is generated by the microstrip antenna. Affects the radiation field ".

In order to solve such a problem, a microstrip antenna as described below has been conventionally considered. FIG. 15A is a perspective view showing another example of the conventional microstrip antenna, and FIG.
15A is a sectional view taken along line AA in FIG. In these figures, reference numeral 112 denotes an antenna element, 111 denotes a ground conductor, and 110 denotes a first dielectric film. A microstrip antenna 114 is configured by the antenna element 112, the ground conductor 111, and the first dielectric film 110.

Reference numeral 113 denotes a strip-shaped conductor.
Reference numeral 115 denotes a second dielectric film. Strip-shaped conductor 11
3. The microstrip line 116 is constituted by the second dielectric film 115 and the ground conductor 111.
Reference numeral 117 denotes a slot formed in the ground conductor 111. The signal propagating through the microstrip line 116 is transmitted through the slot 117 to the antenna element 112.
To the microstrip antenna 11
Excitation 4

In the microstrip antenna shown in FIGS. 15A and 15B, the microstrip line 116 serving as a feed line is on the opposite side of the antenna element 112 with respect to the ground conductor 111. Unwanted radiation from 116 has little effect on the radiation field of microstrip antenna 114.

The characteristics of the microstrip antenna shown in FIGS. 14A, 14B, 15A, and 15B depend on the relative dielectric constant of the first dielectric film 110 (or 100). It is determined from the coefficient, the dielectric loss tangent (tan δ) and the thickness (h), and the conductivity (σ) of the antenna element 102 (or 112).

FIG. 16 is a graph showing an example of the relationship between the radiation efficiency and the no-load Q of the circular microstrip antenna when the surface wave is not considered. (K. Hirasa
waand M.W. Haneishi, "Analysi
s, Design, andMeasurement o
f Small and Low-Profile A
ntennas, "Arttech House, Nor
wood, MA02062)

Here, assuming that S is a standing wave ratio (VSWR), the bandwidth BW of the antenna is expressed by the following equation.

(Equation 1)

Thus, the bandwidth of the antenna is equal to the no-load Q
As shown in FIG. 16, in order to obtain good antenna characteristics (high radiation efficiency, wide bandwidth, etc.), the thickness h of the dielectric film is preferably large as shown in FIG. But,
When the thickness h is increased, the loss due to the surface wave cannot be ignored, and when the thickness h is increased to a certain degree or more, higher modes are excited in the thickness direction of the dielectric film, and the microstrip antenna does not operate well. Therefore, when designing a good antenna, the thickness of the dielectric film h
Is the most important design parameter. Generally, in a microstrip antenna, １ ／ of the wavelength of the center frequency is used.
In many cases, a dielectric film having a thickness of 0 to 1/20 is used.

On the other hand, a microstrip antenna has many advantages such as light weight and thinness, but has a single frequency operation and a high Q value and a narrow bandwidth.
Broadbanding was an unavoidable issue for widespread use. To cope with these problems, the following dual-frequency microstrip antenna has been developed. FIG. 17A is a plan view showing an example of a conventional dual frequency shared microstrip antenna.
FIG. 17B is a sectional view taken along line AA in FIG. The dual-frequency microstrip antenna shown in this figure is obtained by laminating two dielectric films 100 and forming antenna elements 102 having the same dimensions between the films and on the films. Each antenna element 102 has a dielectric film 100
The power is directly supplied to the power supply pin 200 from the ground conductor 101 side formed on the opposite surface of the power supply. Here, the upper and lower antenna elements 102 have different boundary conditions of electromagnetic field components,
As a result, the equivalent dielectric constant is different, so that the microstrip antenna shown in this figure operates as a dual-frequency microstrip antenna. That is, assuming that the relative dielectric constant of the upper dielectric film 100 is εr1 and the relative dielectric constant of the lower dielectric film 100 is εr2, the equivalent dielectric constant of the antenna element 102 disposed above is (εr1 + 1) /
2. The equivalent dielectric constant of the antenna element 102 disposed below is approximately expressed as (εr1 + εr2) / 2. In a Teflon substrate or a PTFE substrate (relative permittivity εr is about 2.55) which is often used as a dielectric film of a microstrip antenna, there is little change in equivalent permittivity, and the two antenna elements resonate at close frequencies. . Therefore, if a dielectric film having an optimum substrate thickness for one antenna element is used, an optimum substrate thickness for the other antenna element may not be obtained, resulting in a decrease in efficiency and a decrease in bandwidth.

FIGS. 18A and 18B show a microstrip antenna which solves the above problem. FIG. 18A is a plan view showing another example of the conventional dual-frequency microstrip antenna, and FIG.
FIG. 19A is a cross-sectional view taken along the line AA in FIG.
In the dual-frequency microstrip antenna shown in this figure, the sizes of the two antenna elements 102a and 102b are different. Thus, the large antenna element 102a formed on the upper side operates for low frequency, and the small antenna element 102b formed on the lower side operates for high frequency. Therefore, it is possible to optimize the thickness of the dielectric film for each antenna element. However, the dual-frequency microstrip antenna described so far supplies power using the power supply pin 200, so "unwanted radiation from the power supply pin affects the radiation magnetic field of the antenna element."
Had an undesired problem.

FIGS. 19A and 19B show a microstrip antenna which solves the above problem. FIG. 19A is a plan view showing another example of a conventional dual-frequency microstrip antenna, and FIG.
FIG. 20 is a sectional view taken along line AA in FIG.
In the dual-frequency microstrip antenna shown in this figure, the antenna element 102a,
A strip-shaped conductor 113 is formed on the side opposite to 102b. Each of the antenna elements 102a and 102b is electromagnetically coupled to the strip-shaped conductor 113 via the slot 117 and is excited. Also, in the dual frequency shared microstrip antenna shown in this figure, as in FIGS. 18A and 18B, two antenna elements 102a,
The size of 102b is different. Thus, the large antenna element 102a formed on the upper side operates for low frequency, and the small antenna element 102b formed on the lower side operates for high frequency. Therefore, each antenna element 1
It is possible to optimize the thickness of the dielectric film with respect to 02a and 102b. However, the dual-frequency microstrip antenna described so far has a dielectric film thickness of 2 mm.
Since it is optimal for one operating frequency band, it is difficult to simultaneously realize an antenna that operates well for another frequency band, and it is difficult to realize a multi-band antenna.

FIGS. 20A and 20B show a microstrip antenna which solves the above problem. FIG. 20A is a plan view showing another example of the conventional dual frequency shared microstrip antenna, and FIG.
FIG. 21 is a cross-sectional view taken along the line AA in FIG.
In the dual-strip microstrip antenna shown in this figure, a half-wavelength printed dipole 201a having a different resonance length is used.
To 201f are arranged on the dielectric film 100, and the ground conductor 10
1, the half-wavelength printed dipoles 201a to 201a-2
On the side opposite to 01f, a strip-shaped conductor 113 is formed. And each half-wavelength printed dipole 201a-2
01f is electromagnetically coupled to the strip-shaped conductor 113 via the slot 117 and is excited. Thus, the dual-frequency microstrip antenna shown in this figure operates as a multi-band antenna.

However, in this dual-frequency microstrip antenna, each half-wavelength printed dipole 201a
Since -201f are formed on the same dielectric film 100, the frequency range in which the operation is optimally performed is narrowed. In addition, since each of the half-wavelength print dipoles 201a to 201f is excited by being coupled to the slot 117, the number of half-wavelength print dipoles that can be arranged on the slot 117 is physically limited. Thus, FIG.
According to the methods shown in FIG. 0A and FIG. 20B, it is difficult to simultaneously form microstrip antennas having greatly different operating frequencies on the same dielectric film. That is, with the conventional dual-frequency microstrip antenna, it has been difficult to simultaneously realize a multiband antenna that operates arbitrarily and satisfactorily for a plurality of operating frequencies in a wide frequency range.

[0017]

As described above, in the conventional microstrip antenna, any of a plurality of operating frequencies within an ultra-wideband frequency range (microwave band to millimeter wave band) can be used. Each antenna has an optimum substrate thickness, and a multi-band antenna that can operate well cannot be formed simultaneously on the same substrate.

The present invention has been made to solve the above-mentioned conventional problems, and is applicable to a plurality of operating frequencies arbitrarily within an ultra-wide band frequency range (microwave band to millimeter wave band). Each antenna has an optimum substrate thickness, and a multi-band antenna that can operate well can be formed on the same substrate at the same time. The purpose is to obtain a multifunctional microstrip antenna.

[0019]

According to the first aspect of the present invention,
A plurality of dielectric films having different relative dielectric constants and film thicknesses are laminated on each dielectric film, and a plurality of multilayer dielectric films formed by the lamination are further laminated. , The antenna element and the connection of the antenna element
A ground conductor film as a ground conductor, wherein the antenna element
Is any one of the dielectric films constituting the multilayer dielectric substrate
And the ground conductor film is formed on the film surface of the multilayer dielectric.
Formed on the film surface of any of the dielectric films constituting the substrate,
The surface of the dielectric film on which the antenna element is formed is
The dielectric film on which the ground conductor film is formed has a different surface . According to a second aspect of the present invention, in the microstrip antenna according to the first aspect, a film surface of any one of the dielectric films facing the antenna element with the ground conductor film interposed therebetween and constituting the multilayer dielectric substrate. A high-frequency line formed in contact with the antenna, and a slot formed in the ground conductor film, and a signal input to the high-frequency line is electromagnetically coupled to the antenna element to excite the antenna element. It is characterized by having. A third aspect of the present invention is the microstrip antenna according to the first aspect, wherein the microstrip antenna faces the antenna element with the ground conductor film interposed therebetween and constitutes the multilayer dielectric substrate.
A high-frequency line formed in contact with the film surface of the dielectric film, a slot formed in the ground conductor film, one end of the high-frequency line and the antenna element are directly connected at the slot, A conductor for exciting the antenna element. The invention described in claim 4 is the third invention.
The microstrip antenna according to any one of the preceding claims, wherein the conductor is a through hole. According to a fifth aspect of the present invention, in the microstrip antenna according to any one of the first to fourth aspects, the high-frequency line is a microstrip line. According to a sixth aspect of the present invention, in the microstrip antenna according to any one of the first to fourth aspects, the high-frequency line is a triplate line. According to a seventh aspect of the present invention, in the microstrip antenna according to any one of the first to sixth aspects, a plurality of the antenna elements are provided. According to an eighth aspect of the present invention, in the microstrip antenna according to any one of the first to seventh aspects, any one of the dielectric films constituting the multilayer dielectric substrate
And an electronic circuit that contacts a surface of the antenna element and processes a transmission / reception signal of the antenna element. According to a ninth aspect of the present invention, there is provided the microstrip antenna according to any one of the first to eighth aspects, further comprising an electronic circuit in contact with the ground conductor film and for processing a transmission / reception signal of the antenna element. It is characterized by. According to a tenth aspect of the present invention, in the microstrip antenna according to any one of the first to ninth aspects, a part of a dielectric film constituting the multilayer dielectric substrate is removed. . According to an eleventh aspect of the present invention, in the microstrip antenna according to any one of the first to tenth aspects, the multilayer dielectric films are mutually connected.
A circuit element is provided on a contact surface. According to a twelfth aspect of the present invention, in the microstrip antenna according to the eleventh aspect, the circuit element is a capacitor. According to a thirteenth aspect, in the microstrip antenna according to the eleventh aspect, the circuit element is a resistor. According to a fourteenth aspect of the present invention, in the microstrip antenna according to any one of the first to thirteenth aspects,
At least one of the plurality of types of dielectric films is an alumina ceramic. According to a fifteenth aspect, in the microstrip antenna according to any one of the first to thirteenth aspects, the plurality of types of the microstrip antenna are provided.
At least one kind of the dielectric film is a polyimide.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a perspective view showing a first embodiment of the present invention, and FIG. 1B is a sectional view taken along line AA in FIG. 1A. In these figures, reference numeral 1 denotes a first dielectric film, 2 denotes a second dielectric film, 11 denotes a ground conductor, 12 denotes an antenna element,
13 is a strip conductor, 14 is a microstrip antenna, 15 is a microstrip line, and 16 is a slot.

As shown in FIG. 1 (b), the film surfaces of the dielectric film 1 and the dielectric film 2 are 1a, 1b, 1
c, 1d and 2a, 2b, 2c, 2d, 2e.
The ground conductor 11 is formed on the film surface 1c, and the antenna element 12 is formed on the film surface 2e. The antenna element 12
Dielectric film 1 and dielectric film 2 located above film surface 1c
As a dielectric substrate, the microstrip antenna 14
Works as

A strip conductor 13 is formed on the film surface 1b. A microstrip line 15 is formed by the strip-shaped conductor 13, the dielectric film 1 and the ground conductor 11.
Are formed. In this figure, a signal propagated through a microstrip line 15 is electromagnetically coupled to an antenna element 12 via a slot 16 formed in the ground conductor 11 to excite a microstrip antenna 14. When the microstrip antenna 14, which is a kind of resonator, is excited, a radio wave is emitted upward in FIG.

According to the embodiment of FIG.
1 and the antenna element 12 can be formed between any one of the dielectric film 1 and the dielectric film 2. The thickness of the dielectric film 2 is smaller than that of the dielectric film 1. Therefore, as in the second embodiment shown in FIG. 2, the formation positions of the ground conductor and the antenna element are changed to 11a and 1a.
By changing the thickness as in 2a, the thickness of the dielectric substrate of the microstrip antenna can be freely changed. Therefore, a substrate thickness for obtaining good antenna characteristics for an arbitrary frequency band can be obtained. Therefore, even when the transmission frequency and the reception frequency are far apart from each other or when the frequency bands used are significantly different, a microstrip antenna that operates well in any frequency band is formed simultaneously as shown in FIG. can do.

In FIG. 2, the microstrip lines 15 and 15a as feed lines and the antenna element 1
2 and 12a are shielded from each other by the ground conductor films 11 and 11a.
The influence of the unnecessary radiation magnetic field from 5a can be suppressed.

Further, by using alumina, aluminum nitride, silicon, or the like as the first dielectric film 1, the antenna element 12 can be reduced in size. In addition, since the thermal expansion coefficients of these materials are in good agreement with the thermal expansion coefficients of semiconductor materials used in microwave and millimeter wave bands, integration with an electronic circuit formed on a semiconductor substrate is easy. At the same time, a multifunctional antenna device can be realized. Further, by making the relative dielectric constant of the dielectric film 2 smaller than the relative dielectric constant of the dielectric film 1, the equivalent dielectric constant of a microstrip antenna used at a high frequency can be reduced. realizable.

FIGS. 3A and 3B are graphs showing measurement results of the return loss characteristics of the microstrip antenna using the structure shown in FIG. In this microstrip antenna, a 10 GHz band microstrip antenna and an 18 GHz band microstrip antenna are simultaneously formed. FIG. 3A shows the characteristics of a 10 GHz band microstrip antenna, and FIG.
Indicates the characteristics of the 18 GHz band microstrip antenna. Note that the first dielectric film 1, the second dielectric films 2, 10
GHz band microstrip antenna and 18GHz
Table 1 and Table 2 show the structural parameters of the band microstrip antenna.

In the microstrip antenna used for the measurement, in order to perform on-wafer evaluation, a feed line is formed on the same side as the antenna element with respect to the ground conductor, and power is directly supplied using a through hole. Further, the formation positions of the antenna element, the ground conductor, and the center conductor of the microstrip line in Table 2 are shown in FIG.
a, 1c, 2a, and 2e.

[0028]

[Table 1]

[0029]

[Table 2]

3 (a) and 3 (b), microstrip antennas (10G
It can be seen that the Hz band antenna and the 18 GHz band antenna) can be formed simultaneously with the same ratio band.

Since the relative dielectric constant and the thickness of the second dielectric film 2 are smaller than the relative dielectric constant and the thickness of the first dielectric film 1, for example, if the above-mentioned multilayer dielectric film is used, 20
Microstrip antenna in a frequency band exceeding 0 GHz (microstrip antenna having a dielectric film having a thickness of 1/50 to 1/20 of the wavelength of the center frequency)
It is also possible to simultaneously realize arbitrary and plural microwave band / millimeter wave band microstrip antennas of different use frequency bands.

FIG. 4 is a sectional view showing a third embodiment of the present invention. In this figure, FIGS. 1 (a) and 1 (b)
The same components are denoted by the same reference numerals.
In FIG. 4, similarly to FIGS. 1A and 1B, numeral 1 is a first dielectric film, and numeral 2 is a second dielectric film. The film surfaces of the dielectric film 1 and the dielectric film 2 are changed from the bottom to 1a, 1b, 1c, 1d, 2a, 2b, 2c, 2
d and 2e. A ground conductor 11 is formed on the film surface 1c,
The ground conductor 17 is formed on the film surface 1a, and the antenna element 12 is formed on the film surface 2e.

The antenna element 12 operates as a microstrip antenna 14 using the dielectric films 1 and 2 located above the film surface 1c as a dielectric substrate.
A strip conductor 13 is formed on the film surface 1b. The strip-shaped conductor 13, the dielectric film 1, the ground conductor film 11 and the ground conductor film 17 make the triplate line 1
8 are formed.

Next, the operation will be described. The signal propagating through the triplate line 18 is electromagnetically coupled to the antenna element 12 via the slot 16 formed in the ground conductor 11, and excites the microstrip antenna 14. When a microstrip antenna 14 which is a kind of resonator is excited, a radio wave is emitted upward in FIG.

Conventionally, when a triplate line is used, a parallel plate mode (TEM wave) propagating between ground conductors occurs, causing problems such as power leakage and unnecessary coupling. For these issues,
In the vicinity of the feeding point (slot), a method of connecting the ground conductors with a short-circuit pin or the like is effective. However, according to the third embodiment, the short-circuit pin is connected to the ground conductor without using solder as in the related art. It can be formed using holes.

FIG. 5 is a sectional view showing a fourth embodiment of the present invention. In this figure, FIG. 1 (a) and FIG.
The same components as those in (b) are denoted by the same reference numerals. In FIG. 5, reference numeral 1 denotes a first dielectric film, and 2 denotes a second dielectric film. As in FIG. 1,
The film surfaces of the dielectric film 1 and the dielectric film 2 are respectively set to 1a, 1b, 1c, 1d, 2a, 2b, 2c, 2d, 2
e.

The ground conductor 11 is formed on the film surface 1c, and the antenna element 12 is formed on the film surface 2e. The antenna element 12 operates as a microstrip antenna 14 using the dielectric films 1 and 2 located above the film surface 1c as substrates. A strip conductor 13 is formed on the film surface 1b. A microstrip line 15 is formed by the strip conductor 13, the dielectric film 1, and the ground conductor 11.

Next, the operation will be described. The signal propagating through the microstrip line 15 directly excites the microstrip antenna 14 through the through hole 19. Here, the through hole 19 connects one end of the strip conductor 13 and the antenna element 12. And, a microstrip antenna 1 which is a kind of resonator
When 4 is excited, a radio wave is emitted upward in FIG.

FIG. 6 is a sectional view showing a fifth embodiment of the present invention. In this figure, each numeral code is the same as the numeral code in the other embodiments described so far. This embodiment shows an example in which two antennas having different feeding methods such as a microstrip line and a triplate line are integrated. Thus, in the microstrip antenna of the present invention, different types of power feeding methods may be mixed.

FIGS. 7A and 7B are sectional views showing a sixth embodiment of the present invention. In this figure,
Numeral code 20 indicates an electronic circuit formed on the semiconductor substrate, and the other numeral codes are the same as those of the other embodiments. In the present embodiment, an electronic circuit 20 formed on a semiconductor substrate is integrated with a microstrip antenna.

The microstrip antenna shown in FIG. 7A and FIG.
In these figures, the electronic circuit 20
Position is different. That is, in FIG. 7A, a part of the dielectric film 1 is removed, and the ground conductor 1 exposed by the removal is removed.
On one, one electronic circuit 20 is provided. In the same figure, the other electronic circuit 20 is provided on the surface of the dielectric film 1. In contrast, FIG.
In (b), a part of the dielectric film 2 is removed, and one electronic circuit 20 is arranged on the dielectric film 1 exposed by the removal. In the same figure, the other electronic circuit 20 is provided on the surface of the dielectric film 2.

As described above, the microstrip antenna of the present invention can be integrated with an electronic circuit formed on a semiconductor substrate to reduce the transmission loss from a high-frequency circuit to an antenna element, and can be used in a phased array antenna. The active antenna can be made small and thin. Further, according to the microstrip antenna of the present invention, by removing a part of the multilayer dielectric film and inserting the electronic circuit, the wire connecting the electronic circuit and the high-frequency line can be shortened. It has the effect of reduction and can be made thinner. Further, by using the ground conductor 11 of the microstrip antenna 14 as a ground conductor of the electronic circuit, or by mounting the electronic circuit on a dielectric film having a coefficient of thermal expansion that matches well with the semiconductor substrate, heat generated in the electronic circuit can be reduced. Heat can be dissipated efficiently.

In each of the above embodiments, one microstrip antenna has one antenna element. However, the present invention is similarly applied to an array antenna in which a plurality of antenna elements are arranged. It goes without saying that you can do it. Further, in each of the above embodiments, the circular antenna element 12 is shown as the antenna element, but an antenna element of any other shape may be used.

FIG. 8A is a plan view showing a seventh embodiment of the present invention, and FIG. 8B is a cross-sectional view taken along line AA in FIG. 8A. In this figure, parts corresponding to the parts in the above embodiments are given the same reference numerals, and the description thereof is omitted. In the microstrip antenna shown in this figure, a large antenna element 12 for low frequency is arranged on a film of the second dielectric film 2, and a small antenna element 12 a for high frequency is placed between the films of the second dielectric film 2. Has been arranged.

FIG. 9 (a) is a plan view showing an eighth embodiment of the present invention, and FIG. 9 (b) is a sectional view taken along line AA in FIG. 9 (a). In this figure, parts corresponding to the parts in the above embodiments are given the same reference numerals, and the description thereof is omitted. In the microstrip antenna shown in this figure, in the second multilayer dielectric film,
Half-wavelength printed dipoles 21a to 21c having different resonance lengths are arranged on or between different films.

FIGS. 8A, 8B, and 9
In the microstrip antenna shown in FIG. 9A and FIG. 9B, the antenna band is broadened by arranging antenna elements having slightly different operating frequencies on different film surfaces of a thin dielectric film. In addition, the thickness of the dielectric film for each antenna element can be optimized. That is, the microstrip antennas according to the seventh and eighth embodiments of the present invention can realize a wider band without deteriorating antenna characteristics.

In the sixth embodiment, a part of the first multilayer dielectric film or the second multilayer dielectric film is removed, and an electronic circuit is provided on the dielectric film exposed by the removal. Although an example has been shown, it is conceivable that an antenna element is arranged on the dielectric film exposed by the removal, or nothing is arranged in a space created by the removal.

FIG. 10 (a) is a plan view showing a ninth embodiment of the present invention, and FIG. 10 (b) is a sectional view taken along line AA in FIG. 10 (a). In this figure, parts corresponding to the parts in the above embodiments are given the same reference numerals, and the description thereof is omitted. In the microstrip antenna shown in this figure, a part of the second multilayer dielectric film is removed, and the antenna element 12 is arranged on the dielectric film 2 exposed by the removal. Thereby, the dielectric loss of the microstrip antenna 14 can be reduced, and the radiation efficiency can be improved.

FIG. 11A is a plan view showing a tenth embodiment of the present invention, and FIG.
FIG. 2A is a sectional view taken along line AA in FIG. In this figure, parts corresponding to the parts in the above embodiments are given the same reference numerals, and the description thereof is omitted. In the microstrip antenna shown in this figure, a space 22 is formed below the antenna element 12 by removing a part of the dielectric film 1 and a part of the dielectric film 2. This allows
The equivalent dielectric constant of the antenna element 12 can be reduced, and the gain / band can be improved.

In each of the above embodiments, it is conceivable to arrange a circuit element (capacitor, resistor, etc.) on the joint surface between the first multilayer dielectric film and the second multilayer dielectric film. FIG. 12A is a plan view showing an eleventh embodiment of the present invention, and FIG. 12B is a cross-sectional view taken along line AA in FIG. 12A. In this figure, parts corresponding to the parts in the above embodiments are given the same reference numerals, and the description thereof is omitted. In the microstrip antenna shown in this figure, a capacitor 23 is arranged on a joint surface between a first multilayer dielectric film and a second multilayer dielectric film. The capacitor 23 is connected to the electronic circuit 20 via the through hole 19 and the wire bond 24. Thereby, the electronic circuit 20 (active device, MMI
C chip, etc.), a chip capacitor for DC bias which is indispensable when mounting the chip can be removed.
The cost required for mounting the bias chip capacitor can be greatly reduced. When a resistor is mounted, a Wilkinson divider can be formed by using the resistor, so that a power supply circuit having excellent isolation between terminals can be realized. This can reduce the influence between the antenna elements due to the mismatch of the feed line.

Further, in each of the above embodiments, two multilayer dielectric films (first multilayer dielectric film and second multilayer dielectric film) are used, but the number of multilayer dielectric films is not limited to this. It is not limited. FIG. 13A shows a twelfth embodiment of the present invention.
FIG. 13B is a plan view showing the embodiment of FIG.
FIG. 3A is a sectional view taken along line AA in FIG. In this figure, parts corresponding to the parts in the above embodiments are given the same reference numerals, and the description thereof is omitted. In the microstrip antenna shown in this figure, a dielectric film 1 is laminated to form a first multilayer dielectric film, and a dielectric film 2 is laminated to form a second multilayer dielectric film. 25 are laminated to form a third multilayer dielectric film. The three types of multilayer dielectric films are stacked. Furthermore, the second
The antenna element 12 is provided on the multilayer dielectric film, the antenna element 12a is provided on the third multilayer dielectric film, and the ground conductor 11 and the strip conductor 13 are provided on the first multilayer dielectric film. Thereby, a multi-band microstrip antenna can be formed bidirectionally with the ground conductor 11 interposed therebetween.

Further, in each of the above embodiments, each of the multilayer dielectric films has four layers, but the number of layers of the multilayer dielectric film is not limited to this. Alternatively, two antenna elements may be used to excite the terminals with a phase difference of 90 degrees. Further, a degenerate separation element may be provided in the microstrip antenna to excite circularly polarized waves.

The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and the design can be changed without departing from the scope of the present invention. Even if there is, it is included in the present invention.

[0054]

Since the microstrip antenna of the present invention adopts the above-described configuration, the antenna element and the ground conductor of the microstrip antenna are formed between any dielectric films, and the dielectric film of the microstrip antenna is formed. The thickness can be freely and continuously changed in a large range, and the ground conductor films disposed between different films can be connected to the same potential using through holes.

Therefore, since the thickness of the dielectric film for obtaining good antenna characteristics in an arbitrary operating frequency band from a wide frequency range can be easily obtained, the transmission frequency and the reception frequency may be largely apart. Thus, it is possible to form microstrip antennas having greatly different operating frequency bands.

Further, one of the dielectric films having different thicknesses may be used.
Since it is possible to change the film thickness and the number of films per layer,
A multi-band microwave / millimeter-wave antenna arbitrarily operated in a plurality of different frequency bands can be simultaneously realized on the same substrate. In addition, by forming antenna elements having slightly different resonance frequencies on different film surfaces of a thin dielectric film, it is possible to widen the band without deteriorating the characteristics of each antenna element.

Further, since the relative dielectric constants of the respective multilayer dielectric films are different from each other, the antenna element can be reduced in size by using a dielectric film having a high dielectric constant, and a dielectric film having a low dielectric constant is used. As a result, the gain and efficiency of the antenna can be improved.

Further, by using alumina, aluminum nitride, silicon or the like as the dielectric film, since the coefficient of thermal expansion matches well with the semiconductor material used in the microwave / millimeter wave band, a circuit can be formed on the semiconductor substrate. It is easy to integrate with a monolithic microwave integrated circuit (MMIC) to constitute, and a multifunctional antenna device such as an active antenna can be realized.

Further, by arranging circuit elements such as capacitors and resistors on the joining surfaces of different dielectric films, electronic circuits and active elements can be mounted without using chip capacitors, which is effective in reducing the cost of the active antenna. Have. Further, since the feeder circuit can be configured using a Wilkinson divider having excellent isolation characteristics between terminals, coupling between antenna elements by the feeder circuit can be reduced.

Further, the power supply circuit and the bias circuit can be freely laid out by utilizing the features of the multilayer structure.
The degree of freedom of the power supply circuit and the power supply method is greater than in the past. That is, direct power supply using a through hole and electromagnetic field coupling power supply through a slot can be performed, and a microstrip line and a triplate line can be used as a power supply line. In addition, a short-circuit pin effective for suppressing unnecessary modes, which is a problem in the triplate line, can be formed by through holes without using solder.

[Brief description of the drawings]

FIG. 1A is a perspective view showing a first embodiment of the present invention, and FIG. 1B is a sectional view taken along line AA in FIG. 1A.

FIG. 2 is a sectional view showing a second embodiment of the present invention.

3A is a graph showing a measurement result of a return loss characteristic of a 10 GHz band microstrip antenna, and FIG. 3B is a graph showing a measurement result of a return loss characteristic of an 18 GHz band microstrip antenna.

FIG. 4 is a sectional view showing a third embodiment of the present invention.

FIG. 5 is a sectional view showing a fourth embodiment of the present invention.

FIG. 6 is a sectional view showing a fifth embodiment of the present invention.

FIGS. 7A and 7B are cross-sectional views showing a sixth embodiment of the present invention.

8A is a plan view showing a seventh embodiment of the present invention, and FIG. 8B is a sectional view taken along line AA in FIG. 8A.

9A is a plan view illustrating an eighth embodiment of the present invention, and FIG. 9B is a cross-sectional view taken along line AA in FIG. 9A.

10A is a plan view showing a ninth embodiment of the present invention, and FIG. 10B is a sectional view taken along line AA in FIG. 10A.

11A is a plan view showing a tenth embodiment of the present invention, and FIG. 11B is a sectional view taken along line AA in FIG. 11A.

12A is a plan view showing an eleventh embodiment of the present invention, and FIG. 12B is a sectional view taken along line AA in FIG. 12A.

13A is a plan view showing a twelfth embodiment of the present invention, and FIG. 13B is a sectional view taken along line AA in FIG. 13A.

14A is a perspective view showing an example of a conventional microstrip antenna, and FIG. 14B is a sectional view taken along line AA in FIG. 14A.

15A is a perspective view showing another example of a conventional microstrip antenna, and FIG. 15B is a cross-sectional view taken along line AA in FIG. 15A.

FIG. 16 is a graph showing an example of the relationship between the radiation efficiency and the no-load Q of a circular microstrip antenna.

17A is a plan view showing an example of a conventional dual frequency shared microstrip antenna, and FIG. 17B is a plan view of FIG.
FIG. 3 is a cross-sectional view taken along line AA in FIG.

18A is a plan view showing another example of the conventional dual-frequency microstrip antenna, and FIG. 18B is a plan view of FIG.
It is AA sectional drawing in 8 (a).

19A is a plan view showing another example of the conventional dual-frequency microstrip antenna, and FIG. 19B is a plan view of FIG.
FIG. 9A is a sectional view taken along line AA in FIG.

20A is a plan view showing another example of a conventional dual-frequency microstrip antenna, and FIG. 20B is a plan view of FIG.
FIG. 2 is a sectional view taken along line AA in FIG.

[Explanation of symbols]

1, 2, 25 ... dielectric film, 11, 11a, 17 ...
Ground conductor, 12, 12a ... antenna element, 13 ...
Strip-shaped conductors, 14, 14a, 14b, 14c ...
Microstrip antenna, 15, 15a Microstrip line, 16 Slot, 18 Triplate line, 19 Through hole, 20 Electronic circuit, 21a, 21b, 21c Half wavelength printed dipole, 22 …… Space, 23 …… Capacitor, 24
…… Wire bond

Continuation of the front page (56) References JP-A-59-221007 (JP, A) JP-A-3-182102 (JP, A) JP-A-5-129825 (JP, A) JP-A-1-254008 (JP) JP-A-4-286204 (JP, A) JP-A-4-21203 (JP, A) JP-A-5-102721 (JP, A) JP-A-63-3612 (JP, U) JP-A-63-3612 1-57810 (JP, U) 1996 IEICE General Conference SC-1-11 (58) Fields surveyed (Int. Cl. ⁷ , DB name) H01Q 13/08

Claims (15)

(57) [Claims] 1. A plurality of types of dielectric films having different relative dielectric constants and film thicknesses are laminated for each dielectric film, and a plurality of multilayer dielectric films formed by the lamination are further laminated. A multilayer dielectric substrate, an antenna element, and a ground conductor film that is a ground conductor of the antenna element
And the antenna element constitutes the multilayer dielectric substrate.
The ground conductor film is formed on a film surface of one of the dielectric films, and the ground conductor film forms any one of the multilayer dielectric substrates.
The dielectric element is formed on the film surface of any one of the dielectric films, and is in contact with the film surface of the dielectric film on which the antenna element is formed.
A microstrip antenna, wherein a dielectric film on which a ground conductor film is formed has a different film surface . 2. The microstrip antenna according to claim 1, wherein the microstrip antenna faces the antenna element with the ground conductor film interposed therebetween.
And any one of the dielectrics constituting the multilayer dielectric substrate
A high-frequency line formed in contact with the film surface of the film , and a signal formed on the ground conductor film and input to the high-frequency line are electromagnetically coupled to the antenna element to excite the antenna element. A microstrip antenna, comprising: 3. The microstrip antenna according to claim 1, wherein the microstrip antenna faces the antenna element with the ground conductor film interposed therebetween,
And any one of the dielectrics constituting the multilayer dielectric substrate
A high-frequency line formed in contact with the film surface of the film, a slot formed in the ground conductor film, one end of the high-frequency line and the antenna element are directly connected at the location of the slot, and the antenna element is A microstrip antenna comprising: an exciting conductor. 4. The microstrip antenna according to claim 3, wherein said conductor is a through hole. 5. The microstrip antenna according to claim 1, wherein the high-frequency line is a microstrip line. 6. The microstrip antenna according to claim 1, wherein said high-frequency line is a triplate line. 7. The microstrip antenna according to claim 1, comprising a plurality of said antenna elements. 8. The microstrip antenna according to claim 1, wherein a surface of any one of the dielectric films constituting the multilayer dielectric substrate.
Surface in contact, and micro-strip antenna, characterized by comprising an electronic circuit for processing transmission and reception signals of the antenna elements. 9. The microstrip antenna according to claim 1, further comprising an electronic circuit that is in contact with the ground conductor film and that processes a transmission / reception signal of the antenna element. Microstrip antenna. 10. The microstrip antenna according to claim 1, wherein a part of a dielectric film forming the multilayer dielectric substrate is removed. . 11. The microstrip antenna according to claim 1, wherein a circuit element is provided on a surface where the multilayer dielectric films contact each other . 12. The microstrip antenna according to claim 11, wherein said circuit element is a capacitor. 13. The microstrip antenna according to claim 11, wherein said circuit element is a resistor. 14. The microstrip antenna according to claim 1, wherein at least one of the plurality of types of dielectric films is an alumina ceramic. 15. The microstrip antenna according to claim 1, wherein at least one of the plurality of types of dielectric films is polyimide.