JP2950459B2 - Antenna device - 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 device which is provided, for example, in a portable radio telephone and can be constructed compact.

[0002]

2. Description of the Related Art FIG. 11 shows a conventional antenna device. This antenna device is a case of a diversity antenna installed in a small wireless device. A linear antenna element 12 is mounted so as to protrude from the upper surface of the wireless device housing 11, and the linear antenna element 12 is connected to a matching circuit 13 in the housing 11, and the matching circuit 13 is connected to a receiving unit 15 through a feed line 14. Is done. A built-in antenna element 16 is provided in the housing 11, and the built-in antenna element 16 is connected to a receiving unit 18 through a feed line 17. Although not shown, both outputs of the receivers 15 and 18 are subjected to diversity combining.

[0003]

As described above, the conventional antenna device requires the matching circuit 13 when the antenna element 12 having a wavelength other than 1/4 wavelength is used. For this reason, there was a loss in the matching circuit 13 and the gain of the antenna was reduced.
Further, the matching circuit 13 has a narrow band, and the matching circuit 13 can be multi-staged to obtain a wide band characteristic. However, when the band is widened in such a manner, the loss is further increased.

[0004] Since the linear antenna element 12 and the radio device housing 11 are very close to each other and there is no mechanism for interrupting the current,
The directional pattern characteristic of the linear antenna element 12 was deteriorated under the influence of the housing 11. Further, in a state where the linear antenna element 12 is housed in the housing 11, the linear antenna element 12 is in a mismatched state and hardly radiates.

When a diversity antenna is constructed as shown in FIG. 11, two antenna elements are usually required, which has a disadvantage that the antenna volume is large. As described above, the conventional antenna device has a narrow band with a large loss and a low gain, the directional pattern characteristic is deteriorated under the influence of the object to be installed, and the antenna device hardly radiates when the antenna is housed. Has the disadvantage that two antenna elements are required and the antenna volume becomes large.

An object of the present invention is to provide an antenna device which has a high gain, can easily obtain a wideband characteristic, and is less affected by an installed object. Another object of the present invention is to provide an antenna device having a high gain even when the antenna element is housed, in addition to the above objects. Still another object of the present invention is to provide a very small antenna device even in a diversity configuration.

[0007]

According to the present invention, one end of a linear antenna element is connected to one end of an inner conductor of a coaxial impedance converter, and a first feeder is connected to the other end of the coaxial impedance converter. In addition, a groove is formed in the outer conductor of the coaxial impedance converter along the extension direction thereof to form a slot antenna, and one end of the second feed line is connected to the slot antenna.

[0008] Further, a coil antenna is provided at an end of the linear antenna element on the impedance converter side substantially at the axis thereof, and a coil antenna is provided outside the linear antenna element insulated from the linear antenna element and the impedance converter. Is allowed to enter and exit the impedance converter along its extension direction,
One end of the coil antenna and the linear antenna element are connected with the linear antenna element housed in the impedance converter.

Further, a dielectric cylindrical housing guide for guiding the linear antenna element is provided substantially at the axial center of the impedance converter, and the surface of the housing guide opposite to the linear antenna element is a part of the inner conductor. Is located, when the linear antenna element is housed in the impedance converter, the inner end of the linear antenna element comes into contact with the above part of the inner conductor, and the inner conductor is attached along the housing guide from that position, A tubular holding portion is provided on the linear antenna element side of the impedance converter, an inner conductor is connected to the tubular holding portion, and the linear antenna element is slidably inserted and held in the tubular holding portion.

Alternatively, the linear antenna element can freely enter and exit the impedance converter along its extension direction. When the linear antenna element is housed in the impedance converter at the protruding end of the linear antenna element, its outer conductor is formed. The other end of the second power supply line is connected to a connection point of the first power supply line with the impedance converter, and the impedance when the second power supply line side is viewed from the connection point is a line. The length of the second feed line is selected so as to be extremely high when the linear antenna element is pulled out and to have a low impedance when the linear antenna element is stored, and the impedance when the impedance converter is viewed from the connection point is the linear antenna element. The impedance converter is selected so as to have a low impedance when pulled out and to become extremely high when stored.

Further, in each of the above constructions, the thickness of the inner conductor is not uniform. In each of the above configurations, the second slot antenna is formed by approaching the slot antenna to the outer conductor. In each of the above-described configurations, a metal wire extending along and near the outer conductor and the slot antenna is provided.

[0012]

【Example】

Embodiment 1 FIG. 1 shows an embodiment of the first aspect of the present invention. At one end (the lower end in the figure) of the linear antenna element 21, a coaxial impedance converter 22 is provided substantially on an extension thereof, and an inner conductor 23 of the coaxial impedance converter 22 is connected to the linear antenna element 21. One end of a feed line 24 is connected to the other end of the coaxial impedance converter 22. The power supply line 24 is a coaxial cable whose central conductor is the inner conductor 2.
3 and the outer conductor is connected to the outer conductor 25 of the coaxial impedance converter 22. That is, the feeder 24 side of the coaxial impedance converter 22 is closed by the end plate, and the outer periphery of the outer conductor of the feeder 24 is inserted and connected to the inner periphery of the center hole of the end plate. The outer conductor 25 is formed of a metal cylinder.

A slit 26 is formed in the outer conductor 25 along the extending direction thereof to form a slot antenna 27,
One end of a feed line 28 is connected to the slot antenna 27. That is, the feeder line 28 is formed of a coaxial cable, and one end of each of the center conductor and the outer conductor of the feeder line 28 is connected to both edges of the slit 26 at an intermediate portion of the slot antenna 27. Further, in this example, the slot antenna 2
A capacitor 29 is connected between both edges of the slit 26 so that 7 resonates at the used wavelength. The length of the linear antenna element 21 is preferably about one half of the used wavelength. The width of the slit 26 of the slot antenna 27 is preferably equal to or less than one-tenth of the used wavelength, similarly to a normal slot antenna. The length of the coaxial impedance converter 22 is determined from the point of impedance matching between the linear antenna 21 and the feed line 24,
This length is equal to the length of the slot antenna 27.

Since the slit 26 is cut in a direction orthogonal to the current flowing inside the coaxial impedance converter 22, the slot antenna 27 shares the internal space of the coaxial impedance converter 22. The device 22 and the slot antenna 27 operate independently. The case where the linear antenna element has a half wavelength will be further described. In this case, it is necessary to match the impedance of the feed line 24 to 50Ω and the impedance when the half-wavelength antenna element 21 is fed from the lower end to several hundred Ω. Here, the coaxial impedance converter 22
The characteristic impedance of the coaxial impedance converter 22 is set to a value close to the geometric mean value of the 50Ω and the several hundred Ω, and the length is set to about １ ／ wavelength. To set the coaxial characteristic impedance to, for example, about 200Ω, the ratio of the diameters of the inner conductor 23 and the outer conductor 25 is about 6
Should be fine. That is, for example, the diameter of the inner conductor 23 is 1 m.
If m, the diameter of the outer conductor 25 is 6 mm. According to this configuration, impedance conversion is performed by the impedance converter 22, and the feeder line 24 and the linear antenna element 2
1 can be impedance-matched. However, in this case,
The imaginary part of the impedance may not be perfectly matched. In this case, for example, a capacitor can be loaded in parallel at the connection point between the power supply line 24 and the coaxial impedance converter 22, and the capacitance can be adjusted appropriately to achieve perfect matching. This matching can be applied to other embodiments described later.

On the other hand, the length of the slit 26 may be arbitrary,
The capacitor 29 is connected so as to operate efficiently as an antenna, that is, to resonate at the used wavelength. Thus, in this antenna device, the outer conductor 25 operates as an impedance converter for the linear antenna element 21, and the slit 26 cut thereon operates as a slot antenna 27, so that space can be shared. in this case,
It is necessary to cut the slit 26 in the longitudinal direction with respect to the outer conductor 25, so that both operate independently. This is because while the operation of the coaxial impedance converter 22 uses the current in the longitudinal direction of the outer conductor 25, the slot antenna 27 uses the current in the circumferential direction of the outer conductor 25, and these currents are orthogonal. Because they do. Further, the coaxial impedance converter 22 has a wide band by nature and is not a matching circuit using a lumped constant, so that the loss is small. Further, since the coaxial has a stub effect, the influence of the installed object is small. That is, the coaxial impedance converter 22 and the linear antenna element 2
The impedance when viewed from the connection point with the impedance converter 22 side is extremely high, the current in this portion is small, and the current flowing to the outside becomes extremely small.

Therefore, by adopting such a configuration, an antenna device having a high gain, a wideband characteristic can be easily obtained, the influence of an installation object is small, and a very small diversity device can be realized. it can. Embodiment 2 FIG. 2A shows a second embodiment of the present invention, and portions corresponding to FIG. 1 are denoted by the same reference numerals (the same applies to the following drawings). In this example, a slit 31 is formed in the outer conductor 25 in parallel with the slit 26 to form a second slot antenna 32. The second capacitor 33 is also connected to the second slot antenna 32. In this configuration, since both slits 26 and 31 are cut in the longitudinal direction of the outer conductor 25, both operate without disturbing the coaxial mode current flowing inside the outer conductor 25 in the longitudinal direction. Thereby, the two slot antennas 27, 32
So that one of them is a parasitic element,
The resonance frequencies of the slot antennas 27 and 32 can be relatively close to each other to achieve a wide band, or the resonance frequencies can be relatively separated to provide a two-band characteristic (two resonances). Other effects are exactly the same as those of the first embodiment.

The distance between the slits 26 and 31 is, for example, 0.1.
One wavelength or less is preferable, but a preferable value is determined according to each resonance frequency of the slot antennas 27 and 32 and the thickness of the outer conductor 25. Embodiment 3 FIG. 2B shows a third embodiment of the present invention, in which the thickness of the inner conductor 23 is changed in the middle, and FIG. It was a thick part for 23b. In such a configuration, the coaxial characteristic impedance differs between the narrow portion 23a and the thick portion 23b of the inner conductor 23, so that a two-stage matching circuit can be formed. Therefore, it is possible to obtain a wide band characteristic and a two resonance characteristic. In addition, the thick portion 2 of the inner conductor 23 on the side of the feeder line 24
If 3b is set to the characteristic impedance of 50Ω,
Substantially only the thin portion 23a of the inner conductor 23 operates as a matching circuit, so that a coaxial matching circuit of any length can be realized regardless of the apparent length of the outer conductor 25. Also,
Other effects are exactly the same as those of the first embodiment. Embodiment 4 FIGS. 3 and 4 show a fourth embodiment of the present invention, which is an example of a small diversity antenna for a portable wireless device in which the linear antenna element 21 can be housed and a high gain can be obtained when housed. 3A and 4A show a state where the linear antenna element 21 is pulled out, and FIGS. 3B and 4B show a state where the linear antenna element 21 is housed.

A coaxial impedance converter 22 is accommodated in the radio housing 11 so that the longitudinal direction thereof is vertically oriented.
Are projected outside. The case 11 is formed of a dielectric such as a synthetic resin material. Linear antenna element 2
A coil antenna 34 having its linear antenna element 21 substantially as an axis is provided outside the end on the side of the coaxial impedance converter 22 of FIG. Antenna element 2
1 and the impedance converter 22. The coil antenna 34 is wound around the linear antenna element 21 via a relatively thick dielectric layer 35, for example, and attached thereto.

The linear antenna element 21 can freely enter and exit the coaxial impedance converter 22 along the extension direction. For example, a cylindrical storage guide 36 made of a dielectric material is provided so that the axis of the outer conductor 25 substantially coincides with the axis of the outer conductor 25, and the linear antenna element 21 is held in the storage guide 36 so as to be able to move in and out. Further, in this example, a portion 23b of the inner conductor 23 on the side of the power supply line 24 is a thick portion, and one end of the thick portion 23b is closed, and the inner peripheral surface of the other end on the open surface side is the storage guide 3.
6, so that the linear antenna element 21 can enter into the thick portion 23b. The narrow portion 23a of the inner conductor 23 extends to the linear antenna element 21 along the outer surface of the storage guide 36, and is connected to the linear antenna element 21.

For example, a tubular holding portion 37 made of a metal material is provided on the side of the linear antenna element 21 of the impedance converter 22 so as to substantially coincide with the extension of the axis of the outer conductor 25.
The linear antenna element 21 is slidably inserted and held in the tubular holding portion 37. A brim 38 is formed at the inner end of the linear antenna element 21 for retaining. The thin portion 23a of the inner conductor 23 is connected to the tubular holding portion 37, and the tubular holding portion 37
And is electrically connected to the linear antenna element 21 via.
Note that the coil antenna 34 is wound on the tubular holding portion 37 via the dielectric layer 35. Coil antenna 3
No. 4 has a length along the coil wire of approximately 1/4 wavelength.

The linear antenna element 21 is connected to the coil antenna 34 with the linear antenna element 21 housed in the impedance converter 22. For example, a circular metal plate 39 is provided on the protruding end of the linear antenna element 21.
When the linear antenna element 21 is stored at the center thereof, the metal plate 39 is attached to the upper end 34a of the coil antenna 34.
And is electrically connected. At this time, the metal plate 39 may be elastically contacted with the coil antenna 34 by utilizing the shape of the coil so that good contact is obtained. Further, since the coil antenna 34 and the metal plate 39 need only be electrically connected, they need not necessarily be in mechanical contact with each other. The antenna 34 may be fed.

In this contact state, the metal plate 39 is prevented from contacting the tubular holding portion 37, and the inner end of the linear antenna element 21 enters the thick portion 23b of the inner conductor 23,
The linear antenna element 21 is electrically connected to the feed line 24 via the thick portion 23b, and the coil antenna 34 is excited via the linear antenna element 21. Further, in this example, the inner end of the linear antenna element 21 is in contact with the closed end plate of the thick portion 23b so that the linear antenna element 21 is prevented from being pulled in from the closed end plate.
And an interval is created between them.

Further, in this example, when the linear antenna element 21 is made expandable and contractible, one half 21a of the linear antenna element 21 on the side of the impedance converter 22 is formed in a tube shape, and the other half portion 21b is formed in a tube shape. It is made thin and can slide in and out of the tubular portion 21a. Therefore, the means may be configured in the same manner as a normal telescopic linear antenna.

In the illustrated example, a cylindrical projection 41 communicating with the inside is integrally formed from the upper surface of the housing 11, and the coil antenna 34 is located in the cylindrical projection 41. The coaxial impedance converter 22 is fixed in the housing 11 to hold the antenna device. The power supply lines 24 and 28 are connected to the receiving units 15 and 18 in the housing 11, respectively, and the reception outputs of the receiving units 15 and 18 are diversity-combined by the combining unit although not shown.

Here, the linear antenna element 21 is accommodated in the impedance converter 22 in a two-stage manner, and the length of the extended state is close to 波長 wavelength. 3A and 4A, the linear antenna element 21 is pulled out.
Can be matched by the coaxial impedance converter 22 as in the first embodiment. In this case, the coil antenna 3
4 has no influence on the operation of the linear antenna element 21 because it is not connected anywhere and has no resonance wavelength.

On the other hand, when the linear antenna element 21 is housed in the impedance converter 22 as shown in FIGS. 3B and 4B, the center conductor of the feed line 24 is connected to the inner conductor 23 through the thick portion 23b. Linear antenna element 2 housed
1 and an end of the linear antenna element 21 is connected to one end 34 of the coil antenna 34 by a metal plate 39.
a. Here, the coil antenna 34 is designed in advance to resonate at a used frequency with a low impedance. In this case, the stored linear antenna element 2
1 operates as an inner conductor of the coaxial impedance converter 22. The linear antenna element 21 is thicker than the narrow portion 23a of the inner conductor 23, and the coaxial characteristic impedance of the impedance converter 22 in this case changes to a value lower than the state where the linear antenna element 21 is pulled out. As an example, assuming that the diameter of the linear antenna element 21 is 3 mm and the diameter of the outer conductor 25 is 6 mm, the coaxial characteristic impedance in a state where the linear antenna element 21 is housed is about 50Ω. That is, in this case, the outer conductor 25
And the linear antenna element 21 housed therein operates not as an impedance converter but as a simple 50Ω transmission line, and a connection end 34 a with the coil antenna 34.
Also has a low impedance. This matches the coil antenna 34 that operates with low impedance, and the coil antenna 34 operates and emits sufficient radiation. In this case, the linear antenna element 21 functions as a transmission line, and has no effect on the operation of the coil antenna 34.

Therefore, by adopting such a configuration, an antenna having a high gain is formed in both the pulled-out state and the housed state of the linear antenna element 21. In the above operation, the slot antenna 27 operates completely independently. This is because the slot antenna 27 operates using the current in the circumferential direction of the outer conductor 25, and is orthogonal to the current in the coaxial mode. However, when the linear antenna element 21 is pulled out and stored,
Since the position of the metal inside the outer conductor 25 changes, the resonance frequency of the slot antenna 27 may be slightly shifted.

In the above description, the linear antenna element 21 is 1
Although the outer conductor 25 has a wavelength of about １ ／ wavelength and the outer conductor 25 has a quarter wavelength, the length of the linear antenna element 21 may be arbitrary. In that case, the length and characteristics of the coaxial impedance converter 22 are determined according to the length. The impedance may be set appropriately. For example, when the length of the linear antenna element 21 is set to 0.7 wavelength, the maximum directivity in a vertical plane including the linear antenna element 21 is set upward by about 30 °, or the length of the linear antenna element 21 is set to 0. As the three wavelengths, the lowermost directivity direction may be about 30 ° downward. Note that the maximum directivity direction of the linear antenna element 21 having a wavelength of 0.5 in the vertical plane is the horizontal direction (lateral direction).

3 and 4, the linear antenna element 21
Is pulled out, the outer conductor 25 operates as a stub, so that it is hard to be affected by the components of each part in the housing 11. When the housing 11 is made of metal, the slit of the slot antenna 27 is located on the outer surface of the housing 11. Also in this case, the outer conductor 25 operates as a stub to prevent a current from flowing through the housing 11.

FIGS. 5 to 7 show the results of experiments conducted on the antenna device shown in FIGS. 3 and 4. FIG. This means that the length of the outer conductor 25 is 5 cm, the diameter is 1 cm, the length of the linear antenna element 21 is 10 cm, and the coil antenna 34
Has a diameter of 1 cm and is wound approximately 2.5 times, and the slit 26 has a length of 5
This is an impedance characteristic when the capacitor 29 is about 1 pF in cm, 3 mm in width, and is installed in the dielectric casing 11 of about 200 cc. FIG. 5A shows the linear antenna element 21.
FIG. 5 shows the characteristics of the linear antenna element 21 in a state where
6B shows the characteristics of the slot antenna 27 in the extended state, and FIG. 6A shows the linear antenna element 2 in the extended state.
6B shows the coupling characteristics between the linear antenna element 1 and the slot antenna 27, and FIG. 6B shows the characteristics of the linear antenna element 21 when the linear antenna element 21 is housed. When the antenna is pulled out, the linear antenna element 21 resonates at about 1.44 GHz, the slot antenna 27 resonates at about 1.59 GHz, and the maximum coupling is about 9 dB. When the antenna is housed, it resonates at about 1.46 GHz. ing. That is, in the state where the antenna is pulled out, the linear antenna element 21 and the slot antenna 27 can resonate independently while sharing the same volume, and it can be seen that the coupling thereof is 9 dB. Has also been demonstrated to be resonated at any frequency.

FIG. 7 shows a radiation pattern measurement result when the antenna is pulled out. The housing 11, the linear antenna element 21, the coordinate axes XYZ, and Z along a spherical surface centered on the origin O
Electric field Eθ radiated from axis Z and XY about origin O
FIG. 7A shows the relationship with the electric field Eφ in the counterclockwise direction along the in-plane circle.
B is the horizontal plane (XY) of the linear antenna element 21
The pattern C is the vertical plane (Y-
Z) pattern, D is the horizontal plane (X
(Y) pattern, E is a vertical plane (YZ) pattern of the slot antenna 27. Thus, the horizontal plane pattern of the linear antenna element 21 is almost a perfect circle, and the vertical plane is 8
A pattern close to the shape of a triangle is obtained, and its level is about the same as a dipole antenna. This indicates that the linear antenna element 21 operates as a half-wavelength type antenna and that there is almost no loss. The slot antenna 27 has a relatively unidirectional pattern in a horizontal plane, and its level is about 3 dB lower than that of the dipole antenna. Further, when the correlation coefficient was measured outdoors, the value was 0.6 or less even though both antennas shared the space. It can be seen from the actual measurement results of the radiation pattern and the correlation coefficient that a sufficient diversity effect can be obtained.

Therefore, by adopting this antenna configuration, a high gain, a wide band characteristic can be easily obtained, the influence of the installation object is small, the diversity configuration is very small, and the antenna element housing is further improved. It is possible to provide an antenna device having a high gain even in some cases. Embodiment 5 FIG. 8 shows a fifth embodiment of the present invention. In this example, only the linear antenna element is operated as an antenna when the antenna is pulled out, and only the slot antenna is operated as an antenna when the antenna is stored.
In this embodiment, as in the case of FIG.
Numeral 1 can freely enter and exit the coaxial impedance converter 22 in its extension direction. Therefore, the storage guide 36 can be used similarly. However, in this case, the storage guide 36 is provided over substantially the entire length of the outer conductor 23. Further, a tubular holding portion 37 is similarly provided, and the linear antenna element 21 is slidably held by the tubular holding portion 37.

Further, in this example, the other end of the feed line 28 of the slot antenna 27 is connected in parallel with the feed line 28 at a connection point between the impedance converter 22 and the feed line 24. The length of the impedance converter 22 is about 1/4 wavelength.
A short-circuit portion 43 for connecting the protruding end of the linear antenna element 21 to the outer conductor 25 in a state where the linear antenna element 21 is housed.
Is provided. In the illustrated example, the distal end of the linear antenna element 21 is bent at substantially a right angle to form a short-circuit portion 43.
In order for the short-circuit portion 43 to make good contact with the outer conductor 25, the inner conductor 23
The small contact piece 44 is integrally extended to the side, and the linear antenna element 2
When 1 is stored, the short-circuit portion 43 comes into contact with the small contact piece 44. In order to prevent the linear antenna element 21 from rotating around its axis, for example, a part of the retaining collar 38 (see FIG. 4) is cut out to provide a linear portion, and the storage guide 36 is provided.
May be made to match the peripheral surface shape of the collar 38.

The capacitance of the capacitor 29 is selected so that the slot antenna 27 resonates at a desired frequency in a state where the linear antenna element 21 is housed, and the impedance when the feed line 28 side is viewed from the connection point of the feed lines 24 and 28 is adjusted. , The characteristic impedance of the coaxial cable should be 50Ω. Further, since the resonance frequency of the slot antenna 27 is reduced and the frequency band is narrow when the linear antenna element 21 is pulled out, the impedance when the feed line 28 is viewed from the connection point of the feed lines 24 and 28 is significantly increased. Is done.

Therefore, when the antenna is pulled out, the feed line 2
When viewed from the connection points 4 and 28, the impedance when the slot antenna 27 is viewed through the feed line 28 is extremely large, and only the impedance of the linear antenna element 21 converted to 50Ω by the coaxial impedance converter 22 is visible. , From the linear antenna element 21. On the other hand, in the antenna housed state, when the coaxial impedance converter 22 is viewed from the connection point of the feeder lines 24 and 28, since the tip is short-circuited by the short-circuit portion 43, it is 1/4.
It becomes a wavelength short-circuit line and has an infinite impedance.
However, since the slot antenna 27 side is matched to 50Ω, the slot antenna 27
Is supplied and radiated from the slot antenna 27.

In the case of this configuration, in order to form a diversity antenna, as shown in the second embodiment, two slits may be cut and one may be a slot antenna dedicated to the diversity antenna. Therefore, by adopting this antenna configuration, a high gain, a wide band characteristic can be easily obtained, the influence of the installation object is small, and a diversity configuration can be adopted. Further, it is possible to provide an antenna device having a high gain even when the antenna is housed. Embodiment 6 FIG. 9 shows a sixth embodiment of the present invention. A metal wire 45 is provided close to both the outer surface of the outer conductor 25 and the slot antenna 27 and along the slot antenna 27. A dielectric spacer 46 is interposed between the metal wire 45 and the outer conductor 25. An adjustment capacitor 47 is connected between the metal wire 45 and the outer conductor 25. The metal wire 45 may be a round wire or a plate wire. With such a configuration, since the metal wire 45 is very close to the slot antenna 27, it operates as a parasitic element, and its resonance frequency is adjusted by the capacitor 47 to adjust the resonance frequency of the slot antenna 27. By approaching the resonance frequency, the band of the slot antenna 27 can be expanded. In this case, the metal wire 45
Is disposed outside the outer conductor 25, so that it does not affect the operation of the linear antenna element 21 at all.

FIG. 10 shows experimental results of impedance characteristics in this case. The antenna structure is the same as that of the fourth embodiment. A plate-shaped metal wire 45 having a length of 5 cm and a width of 2 mm is provided as a parasitic element at a distance of about 5 mm from the slot antenna 27, and capacitors 1 of about 1 pF are provided at both ends. Connected. FIG. 10A is a Smith chart diagram, FIG.
Is a return loss diagram. When FIG. 10B is compared with FIG. 5B in the case where the parasitic element is not installed, it can be seen that the band is clearly widened. Further, in FIG. 10A, a characteristic of drawing a small circle (kink) near the resonance point is exhibited, which is a phenomenon that appears in an antenna having a wide band characteristic.

Therefore, with this configuration, the same effects as in the above embodiment can be obtained, and the slot antenna 27 can have a wider band. In the embodiment shown in FIG. 3, the thickness of the inner conductor 23 may be uniform, that is, all of the inner conductors 23 may be provided as thin lines along the storage guide 36, or Everything may be made into a thick pipe shape and also serve as the storage guide 36. In the embodiment shown in FIG. 8, a part of the inner conductor 23 may be a thick portion 23b as in the embodiment of FIG. FIG. 2B,
In each of the embodiments shown in FIGS. 3 and 8, two slot antennas may be provided as shown in FIG. 2. In addition, as shown in FIG. 27 may be provided. 2A and 9
2B, the thickness of the internal conductor 23 may not be uniform as shown in FIG. 2B.

[0039]

As described above, according to the present invention, by using a coaxial impedance converter and forming a slot antenna therein, a high gain and a wide band characteristic can be easily obtained. In addition, a small antenna device which is less affected by an installed object can be provided.

Further, the diversity antenna can be miniaturized by the linear antenna element and the slot antenna.
Further, the linear antenna element can be housed in the coaxial impedance converter, and only the linear antenna element can be operated in the antenna pulled-out state, and only the slot antenna can be operated in the housed state.

Further, by providing a parasitic slot antenna or a parasitic metal wire, the slot antenna can have a wider band or have two-band resonance.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2A is a perspective view showing an embodiment of the present invention in which two slits are cut in a longitudinal direction in a coaxial impedance converter 22, and FIG. 2B is an embodiment of the present invention in which the thickness of an inner conductor 23 is changed in the middle; FIG.

FIG. 3 shows an embodiment in which the present invention is applied to a small diversity antenna for a portable wireless device, wherein A is an antenna pulled-out state, and B is a perspective view of an antenna housing.

4 shows a longitudinal section of the embodiment shown in FIG. 3, wherein A is an antenna pulled-out state, and B is an antenna housed state.

5A and 5B show impedance characteristics obtained by experimenting with respect to the antenna state shown in FIG. 3; FIG. 5A is a characteristic diagram of a linear antenna element in an antenna extended state; FIG. 5B is a characteristic diagram of a slot antenna in an antenna extended state;

FIG. 6A is a characteristic diagram of a linear antenna element and a slot antenna when the antenna is pulled out, and FIG. 6B is a characteristic diagram of the linear antenna element when the antenna is housed.

FIG. 7 shows the radiation pattern characteristics of the embodiment shown in FIG. 3, which has been experimentally tested, where A is the linear antenna element;
FIG. 6B is a diagram showing a relationship between a housing, a measured electric field, and coordinates, B is a horizontal plane (XY) pattern of a linear antenna element, C is a vertical plane (YZ) pattern of a linear antenna element, and D is a slot antenna. A horizontal plane (XY) pattern, and E is a vertical plane (YZ) pattern of the slot antenna.

FIG. 8 shows an embodiment in which the slot antenna operates as a dedicated antenna in a state where the linear antenna element is housed, wherein A shows the antenna pulled out state, and B shows the antenna housed state.

FIG. 9 is a perspective view showing an embodiment of the present invention in which a passive element is provided to increase the bandwidth.

10A and 10B are experimental results of impedance characteristics of the embodiment of FIG. 9, in which A is a Smith chart diagram and B is a diagram showing return loss.

FIG. 11 is a diagram showing a diversity antenna in which a conventional antenna device is installed in a small wireless device.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) H01Q 3/00-3/46 H01Q 21/00-21/30 H01Q 23/00 H01Q 25/00-25 / 04 H01Q 1/24 H01Q 5/00 H01Q 9/18 H01Q 9/32 WPI / L (QUESTEL) JICST file (JOIS)

Claims (10)

(57) [Claims] 1. A coaxial impedance converter comprising a linear antenna element, an outer conductor and an inner conductor disposed substantially at the axis thereof, one end of the inner conductor being connected to one end of the linear antenna element. A first feeder line connected to the other end of the impedance converter, a slot antenna having a groove formed in the outer conductor along the extension direction, and a second feeder having one end connected to the slot antenna. An antenna device consisting of electric wires and 2. The linear antenna element is provided at an end of the impedance converter at an end of the impedance converter substantially at an axis, and a coil antenna is provided outside the end thereof insulated from the linear antenna element and the impedance converter. The linear antenna element is allowed to freely enter and exit the impedance converter along an extension direction thereof, and one end of the coil antenna and the linear antenna element in a state where the linear antenna element is housed in the impedance converter. 2. The antenna device according to claim 1, further comprising means for electrically connecting the antenna device to the antenna device. 3. A dielectric cylindrical storage guide for guiding the linear antenna element is provided substantially at the axial center of the impedance converter, and the storage guide is provided on a surface of the storage guide opposite to the linear antenna element. A part of the inner conductor is located, and from the position, the inner conductor is attached along the storage guide, a tubular holding portion is provided on the linear antenna element side of the impedance converter, and the tubular holding portion is provided in the tubular holding portion. The antenna device according to claim 2, wherein the linear antenna element is slidably inserted and held, and the inner conductor is connected to the tubular holding portion. 4. The linear antenna element is allowed to enter and exit the impedance converter along its extension direction, and the linear antenna element is inserted into the impedance converter at a protruding end of the linear antenna element. The other end of the second power supply line is connected in parallel with the first power supply line, and the impedance when the second power supply line side is viewed from the connection point is provided. 2. The antenna device according to claim 1, wherein the length of the second feed line is selected so that the linear antenna element is extremely high when pulled out and has low impedance when stored. 5. A second slot antenna is formed by forming a groove in the outer conductor along a direction in which the outer conductor extends.
The antenna device according to claim 4, wherein one end of the third feed line is connected to the slot antenna. 6. The antenna device according to claim 1, wherein the thickness of the inner conductor is not uniform. 7. The antenna device according to claim 1, wherein a groove is formed in the outer conductor along a direction in which the outer conductor extends, to constitute a second slot antenna. 8. The antenna according to claim 1, wherein a metal wire is provided near and outside the outer conductor and the slot antenna, respectively, and extends along the slot antenna. apparatus. 9. The antenna device according to claim 7, wherein the thickness of the inner conductor is not uniform. 10. The antenna device according to claim 1, wherein a capacitor is connected in parallel to a connection point between the first feeder line and the coaxial impedance converter.