JP2931728B2 - Antenna device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used as a built-in antenna of a portable radio having two resonance characteristics.

[0002] The present invention relates to an antenna device which can obtain two resonance characteristics with a small and simple structure.

[0003]

2. Description of the Related Art FIG. 7 is a diagram showing a configuration of a conventional two-resonance plate antenna device (Japanese Patent Application Laid-Open No. 61-41205). In this antenna device, a first radiating plate 21 is placed on a ground plate 23 to which a ground conductor of a feeder line 27 is connected with a stub 25 having a thickness h ₁ interposed therebetween. 21 with a stub 24 interposed between the main plate 23 and
_{A second} radiating plate 22 is placed at a thickness of ₂ and a non-ground conductor of a feed line is connected to a feeding point 26 of the first radiating plate 21.

The size of the first radiation plate 21 (L ₁ × L ₂ )
And the size of the second radiating plate (L ₃ × L ₄ ), two resonances are obtained by resonating the first radiating plate 21 and the second radiating plate 22 at respective resonance frequencies. . That is, the two plate antennas are independently resonated, and the two antennas are fed by one feed line 27 to obtain two resonances.

FIG. 8 shows another conventional example.
(A), (b), and (c) (“Handbook of MICROSTRIP”)
AVTENNAS ", JR James & P.S.Hall). This example shows a partial cross-sectional structure of a microstrip antenna device, where 31 is a first radiation plate, 32 is a second radiation plate, 33 is a ground plate, Feeder lines 34 and 35 also have different sizes and structures of the first radiating plate 31 and the second radiating plate 32, and each of them performs independent resonance to obtain two resonances.

[0006]

[SUMMARY OF THE INVENTION] In the case of the aforementioned two-resonance plate shaped antenna apparatus, the thickness h ₂ from the base plate 23 to the second radiating plate 22, a single composed the first radiation plate 21 of becomes almost twice the thickness h ₁ of the plate-shaped antenna, with thereby increasing the antenna volume, there is a drawback of complicating the structure.

In the case of a microstrip antenna, there is an advantage that each frequency can be set relatively arbitrarily. However, basically, since the antenna has a structure in which two antennas are stacked, the antenna volume is also large. In addition, this microstrip antenna has a disadvantage that multi-resonance characteristics cannot be obtained below the basic resonance frequency.

An object of the present invention is to solve such a problem, and an object of the present invention is to provide an antenna device which can obtain two resonance characteristics with a small and simple structure.

[0009]

According to the present invention, there is provided a conductive ground plate, a conductive radiating plate disposed substantially parallel to the ground plate via an insulator, and a ground conductor connected to the ground plate.
In the antenna device including a feed line connected to a non-grounded conductor to the radiation plate, when the resonance wavelength and λ when the connection point between the ground plate and the radiation plate of the parasitic line is short-circuited, Electrical length is (1/4 + m / 2) λ (however,
m is an integer of 0 or more).

The present invention also provides a conductive ground plate, a conductive radiating plate disposed substantially in parallel with the ground plate via an insulator, a ground conductor connected to the ground plate, and In an antenna device provided with a feeder line to which an ungrounded conductor is connected, when the resonance wavelength when the connection point between the ground plane and the radiation plate of the parasitic line is short-circuited is λ, the electrical length of the parasitic line is ( m / 2) λ (where m is an integer of 1 or more )
It can be characterized by the following.

[0011] The leading end of the parasitic line can be an open end or a short-circuited end, and a slit for adjusting a resonance wavelength can be provided at an end of the radiation plate.

[0012]

By connecting a parasitic line to another connection point distant from the connection point of the power supply line, and setting the connection position, the length of the parasitic line, and the state of the end of the parasitic line in various combinations, The non-feeding line serves as a stub, and this antenna device can be a two-resonance type antenna device.

[0013]

Next, an embodiment of the present invention will be described with reference to the drawings.

(First Embodiment) FIG. 1 is a diagram showing a configuration of a first embodiment of the present invention.

The first embodiment of the present invention comprises a conductive ground plate 2,
A conductive radiating plate 1 arranged substantially parallel to the ground plate 2 via an insulator, a ground conductor 3a is connected to the ground plate 2, and a non-ground conductor 3b is connected to a connection point 3c of the radiating plate 1. And a grounding conductor 4a at the ground plane 2 at another connection point 4c spaced from the connection point 3c of the power supply line 3.
Are connected to the radiation plate 1 and the parasitic line 4 to which the ungrounded conductor 4b is connected is connected.

A transmitter (or receiver) 6 is connected to the feed line 3, and the leading end 5 of the feed line 4 is an open end, and the connection point between the ground plate 2 and the radiation plate 1 of the feed line 4 is short-circuited. When the resonance wavelength is λ, the electrical length of the parasitic line 4 is (1)
/ 4 + m / 2) λ where m is an integer of 0 or more.

In the first embodiment of the present invention constructed as described above, at a low resonance frequency, the connection point 4c of the parasitic line 4 becomes a stub for short-circuiting the ground plate 2 and the radiation plate 1, and operates as a plate antenna. At a high resonance frequency, the ground plate 2 and the radiating plate 1 are open at the connection point 4c of the parasitic line 4, and operate as a general microstrip antenna. At this time, the two resonance frequencies are approximately doubled.

FIG. 2 is a diagram showing the structure and dimensions of an antenna device for which an experiment was conducted with the configuration of the first embodiment of the present invention. The base plate 2 is 330 × 310 mm, and the radiation plate 1 is 100 × 23 m
m, the feeding line 3 is connected to a point 68 mm from the corner of the long side of the radiation plate 1, and the feeding line 4 is connected at a distance of 3 mm, and the feeding line 4 has a length of 60 mm and the tip 5 is open. It was made. This return loss characteristic is shown in FIG.
(A). The low resonance frequency fL is 0.71 GHz,
The high resonance frequency fh is 1.42 GHz, and fL and f
h has a double relationship. On the other hand, the result of measurement without the parasitic line 4 is as shown in FIG. 3B. A resonance point appears at a point substantially equal to the high resonance frequency fh in FIG. It does not show any resonance. Further, the result of an experiment performed using the parasitic wire 4 as a short-circuited metal wire is shown in FIG. 3C, and FIG.
A resonance point appears at a point substantially equal to the low resonance frequency fL, and no resonance is exhibited at the high resonance frequency fh.

From this result, the parasitic line 4 is formed as a short-circuited metal line at the low resonance frequency fL, and the high resonance frequency fh
It can be seen that the operation is performed as open (no connection is made). FIG. 4 shows the result of considering this from the current distribution. FIG. 3A shows the case of a high resonance frequency fh, and FIG. 3B shows the case of a low resonance frequency fL. In the figure, 7
Is a current distribution on a high resonance frequency radiation plate, 8 is a high resonance frequency transmission line current distribution, 9 is a low resonance frequency radiation plate current distribution, 10 is a low resonance frequency transmission line current distribution, and 11 is unpowered. This is a connection point of the electric wire 4. In FIG. 1A, a half-wave current is present on the radiation plate 1 as in a general microstrip, and the parasitic wire 4 also has a half-wave current distribution. Since it becomes such a current distribution,
The parasitic line 4 is a half-wavelength open line and operates in an open state even at the connection point 11 of the parasitic line 4, so that the antenna is a general microstrip antenna regardless of the parasitic line 4. In this case, the current in the parasitic line 4 is
Since the surrounding area has a negative current, it hardly radiates from the parasitic line 4 and does not hinder the operation of the antenna.

On the other hand, in FIG. 2B, since the wavelength is doubled, a current distribution of １ ／ wavelength exists on the radiation plate 1, and the current distribution of the に も wavelength also exists on the parasitic line 4. Since such a current distribution is obtained, the parasitic line 4 becomes an open-ended line of approximately 1/4 wavelength and operates as a short circuit at the connection point 11 of the parasitic line 4, so that the antenna is connected to the radiation plate 1 of the parasitic line 4. The plate antenna is short-circuited at the point and the connection point of the ground plane 2. Also in this case, the current in the transmission line hardly radiates, and does not hinder the operation of the antenna.

Since a general microstrip antenna resonates when the length of the radiating plate 1 is about 波長 wavelength, the resonance frequency of the microstrip antenna having a length of the radiating plate 1 of 100 mm in FIG. Is calculated to be 1.5 GHz, and the high resonance frequency fh of FIG.
Become closer to On the other hand, generally, a plate antenna is
Resonates when the sum of the length and width of the radiating plate becomes about 1/4 wavelength, and in FIG.
When the resonance frequency of the plate antenna of 3 + 23) mm is calculated, it is 0.79 MHz, which is close to the low resonance frequency fL shown in FIG.

The electrical length of the parasitic line 4 is not limited to approximately ほ ぼ of the wavelength of the low resonance frequency, but also
/ 4, 5/4,... １ ／ + m / 2 (m: integer) can perform the same operation.

The connection point between the feeder line 3 and the parasitic line 4 and the shape of the radiation plate 1 are not limited to those of the present embodiment, but use the feature that the parasitic line 4 is short-circuited at a low frequency and opened at a high frequency. Then, different feeder and non-feeder lines, their connection method, and the shape of the radiation plate are conceivable, and an antenna that resonates at twice the resonance frequency with almost the same volume as a plate antenna that operates at a low resonance frequency can be simplified. It can be composed of a structure.

(Second Embodiment) In a second embodiment of the present invention, the electrical length of the parasitic line 4 in the first embodiment is set to 1/4 of the antenna resonance frequency when the connection point is opened, and Are short-circuited. That is, in the first embodiment, the leading end of the non-feeding line 4 is open, but in this embodiment, it is a short circuit. This is because the operation of the parasitic line 4 is 1 /
It becomes a two-wavelength short-circuit line. That is, in other words, the structure of the present embodiment is related to a high resonance frequency. It will be. In addition, this operation is 、 of the high frequency wavelength.
It is understood that a parasitic line having an electric length that is an integral multiple thereof may be used. The operation at each frequency will be described as follows. 5 (a) shows the case of low have resonant frequencies, since the parasitic wire 4 is 1/4-wavelength of the short-circuited line, the radiation plate 1 and the base plate 2 at a connection point unpaid wire 4 is opened <br/> As shown in the current distribution 7 on the radiation plate and the current distribution 8 on the transmission line in FIG. Meanwhile FIG. (B) shows the case of a high has a resonance frequency, since the parasitic wire 4 is 1/2-wavelength short-circuit line, the radiation plate 1 and the base plate 2 at the connection point short
It is contacted by, and operates as a microstrip antenna such as shown in the radiation plate on the current distribution 9 and the transmission line path current distribution 10.

In this case as well, the electrical length of the parasitic line 4 is not limited to approximately 1/4 of the wavelength of the low resonance frequency, but also 3/4, 5/4, ..., 1/4 + m / 2 (m : Integer), the same operation can be performed. In other words,
The electrical length of the parasitic line 4 is approximately equal to the wavelength of the high resonance frequency.
Not only limited to 1/2, but also 1/2, 1, 3/2,
2, ... m / 2 (m is an integer of 1 or more)
do.

The connection point between the feeder line 3 and the parasitic line 4 and the shape of the radiating plate 1 are not limited to those of the present embodiment, and the parasitic line 4 is opened at a low frequency and short-circuited at a high frequency. If you use it, separate feeder and non-feeder,
Considering the connection method and the shape of the radiation plate, an antenna that resonates even at a resonance frequency 1.5 times as large as the microstrip antenna operating at a low resonance frequency can be configured with a simple structure.

(Third Embodiment) A third embodiment of the present invention is such that the radiation plate 1 is provided with a slit 12 as shown in FIG. 6, and the other configuration is the same as that of the first embodiment. In the case of this example, the parasitic line 4 is opened at a high frequency and short-circuited at a low frequency. Therefore, at a high frequency, the radiation plate 1 operates as a microstrip antenna, and since the length in the longitudinal direction is related to the resonance frequency and current flows only in that direction, the linear slit 12 does not affect the resonance frequency. On the other hand, at low frequencies, since the antenna operates as a plate antenna, the length around the radiation plate 1 is related to the resonance frequency, and the resonance frequency can be adjusted by the length of the linear slit 12. Therefore, with such a configuration, it is possible to slightly move the low resonance frequency.

[0028]

As described above, according to the present invention, the two-resonance characteristics (for example, 800 MHz and 150 MHz) have the same volume as a portable single plate antenna and have a simple structure.
0 MHz).

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a configuration of an experimental sample according to the first embodiment of the present invention.

FIGS. 3A, 3B, and 3C are diagrams showing return loss with respect to frequency in the experiment of the first embodiment.

FIGS. 4A and 4B are diagrams showing the configuration and current distribution of the first embodiment of the present invention.

FIGS. 5A and 5B are diagrams showing the configuration and current distribution of a second embodiment of the present invention.

FIG. 6 is a diagram showing a configuration of a third embodiment of the present invention.

FIG. 7 is a diagram showing a configuration of a conventional two-resonance plate antenna.

FIGS. 8A, 8B, and 8C are partial cross-sectional views showing a configuration of a main part of a two-resonance microstrip antenna in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Radiation plate 2, 23, 33 Ground plate 3, 27, 34, 35 Feeding line 3a, 4a Grounding conductor 3b, 4b Non-grounding conductor 3c, 4c, 11 Connection point 4 Parasitic line 5 Tip 6 Transmitter (receiver) 7 , 9 Current distribution on radiation plate 8, 10 Current distribution on transmission line 12 Linear slit 21, 31 First radiation plate 22, 32 Second radiation plate 24, 25 Stub 26 Feeding point

Claims (5)

(57) [Claims] A conductive ground plate, a conductive radiating plate disposed substantially in parallel with the ground plate via an insulator, a ground conductor connected to the ground plate, and an ungrounded conductor connected to the radiating plate. An antenna device having a connected power supply line, wherein a ground conductor is connected to the ground plane and an ungrounded conductor is connected to the radiation plate at another connection point spaced from the connection point of the power supply line. parasitic wire is connected, when shorted to the connection point between the base plate and the radiation plate of the parasitic wire
When the resonance wavelength is λ, the electrical length of the parasitic line is (１ ／ + m / 2) λ , where m is an integer of 0 or more . 2. The antenna device according to claim 1, wherein the end of the parasitic line is an open end. 3. A conductive ground plate, a conductive radiating plate arranged substantially in parallel to the ground plate via an insulator, a ground conductor connected to the ground plate, and an ungrounded conductor connected to the radiating plate. An antenna device having a connected power supply line, wherein a ground conductor is connected to the ground plane and an ungrounded conductor is connected to the radiation plate at another connection point spaced from the connection point of the power supply line. parasitic wire is connected, wherein when the base plate unpaid wire the resonant wavelength when the short-circuit connection point between the radiation plate and lambda, the electrical length of the parasitic wires (m / 2) λ, however, m is 1 or more An antenna device characterized by being an integer. 4. The antenna device according to claim 3 , wherein the end of the parasitic line is a short-circuited end. 5. A conductive ground plate, a conductive radiating plate disposed substantially parallel to the ground plate via an insulator, a ground conductor connected to the ground plate, and an ungrounded conductor connected to the radiating plate. An antenna device having a connected power supply line, wherein a ground conductor is connected to the ground plane and an ungrounded conductor is connected to the radiation plate at another connection point spaced from the connection point of the power supply line. An antenna device, wherein a parasitic line is connected, and a slit for adjusting a resonance wavelength is provided at an end of the radiation plate.