JP2003309429A - Slot feeding type antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a slot feeding type antenna with an enhanced diversity effect for the major purpose and to provide an inexpensive slot feeding type antenna shared for two frequencies for the subordinate purpose. <P>SOLUTION: Parasitic elements 23, 24 of almost a cross shape are placed in parallel with a couple of feeding microstrip lines 6a, 6b orthogonally in opposition to a cross shaped slots 3 and in a manner of opposing to the cross shaped slots 3. Since branches of the parasitic elements 23, 24 opposed to the one feeding microstrip line 6a are resonated and branches of the parasitic elements 23, 24 opposed to the other feeding microstrip line 6b are resonated, a degree of identifying cross polarized waves can be enhanced. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a slot-fed antenna.

[0002]

2. Description of the Related Art For mobile phones, 0.9 GHz band, 1.5 G
Electromagnetic waves in several frequency bands such as the Hz band and the 2 GHz band are used. In the base station antenna, one antenna is often used for each frequency band. Recently, dual-frequency or triple-frequency antennas with only vertical polarization have been studied (Sugimoto, Ebine, IEICE Communication Society Conference, B-1-75 (199).
9)).

On the other hand, in mobile radio communication, a fading phenomenon in which the received power of electromagnetic waves fluctuates due to movement is a problem. As a measure against this fading, there is a diversity system in which a plurality of antennas are used for simultaneous reception and the one with the stronger received power is used for communication. In this diversity method, a space diversity method in which two antennas are installed at separate locations, or two antennas of vertical polarization and horizontal polarization (or ± 45 degrees polarization) are accommodated in one antenna housing. There are polarization diversity methods, directional diversity methods, frequency diversity methods, time diversity methods, etc.

Among them, an antenna in which two antennas are housed in one housing is being studied (Shimura, Kayagomi, Ebine, IEICE Communication Society Conference, B-1-
95 (2000)).

FIG. 9A is a front view showing a conventional example of a slot feed type antenna, and FIG. 9B is a right side view of FIG. 9A.

This slot-fed antenna 1 is ± 45
Degree-polarized diversity directional antenna.

Reference numeral 2 is an antenna element substrate, and a rectangular metal plate (for example, gold-plated copper, silver-plated copper, copper, aluminum) 4 in which a diagonal cross-shaped cut (slot) 3 is formed is used as a rectangular dielectric substrate. It is provided on one surface (left side in FIG. 9B) of (for example, ceramic, glass, resin) 5. On the other surface (right side in FIG. 9B) of the dielectric substrate 5, that is, on the back side of the antenna element substrate 2, a pair of feeding microstrip lines 6a and 6b are provided in a cross shape so as to face the slot 3. Power is supplied to the microstrip lines 6a and 6b for power supply. That is, the radiator is constituted by the slot 3 and the feeding microstrip lines 6a and 6b.

The surface of the antenna element substrate 2 (dielectric substrate 5
On one surface), two parasitic element plates 8 and 9 for guiding the electromagnetic wave from the radiator in the surface direction are provided on four columns 7.
Is supported so as to be parallel to the antenna element substrate 2.

The parasitic element plate 8 is provided with a rectangular parasitic element 11 made of metal on one surface (left side in FIG. 9B) of a substantially rectangular dielectric substrate 10. And the parasitic element plate 9 is a single substantially rectangular dielectric substrate 1
The rectangular parasitic element 13 made of metal is provided on one surface (left side in FIG. 9B) of No. 2.

[0010]

However, there is a problem that the structure becomes complicated when the polarization diversity system is realized by the frequency sharing antenna.

In the slot-fed antenna 1 shown in FIGS. 9A and 9B, one polarization plane (for example, +4) is used.
When transmitting and receiving with a polarized wave of 5 degrees), the parasitic elements 11 and 13 have a rectangular shape with respect to a polarization plane of 45 degrees.
The resonance directions of the electromagnetic field on the surfaces of the parasitic elements 11 and 13 are 0 degree and 90 degrees, and the electromagnetic field having the other polarized wave component (-45 degrees in this case) on the surfaces of the parasitic elements 11 and 13. Is emitted, and the cross polarization discrimination degree deteriorates.

Here, the degree of cross-polarization discrimination is the degree of transmission and reception of electromagnetic waves of orthogonal polarization (cross-polarization) with respect to electromagnetic waves having a desired plane of polarization. The better the degree, the better the diversity effect.

Therefore, a main object of the present invention is to provide a slot-fed antenna with an improved diversity effect, and a secondary object is to provide an inexpensive slot-fed antenna with dual frequency sharing. Especially.

[0014]

In order to achieve the above object, the invention according to claim 1 is an antenna element substrate in which a metal plate having cross-shaped slots is provided on one surface of a dielectric substrate. And a pair of feeding microstrip lines orthogonally provided on the other surface of the dielectric substrate so as to face the slot, and a substantially cross shape arranged parallel to the dielectric plate and facing the slot. A slot-fed antenna including the parasitic element of FIG.

According to a second aspect of the present invention, the second frequency higher than the first frequency band is located on both sides of the cross-shaped slot for the first frequency band and the slot for the first frequency band. A metal plate having a cross-shaped slot for a band is formed so as to face the antenna element substrate provided on one surface of the dielectric substrate and the slot for the first frequency band on the other surface of the dielectric substrate. And a pair of feeding microstrip lines for the first frequency band, which are provided orthogonally to each other, and are provided orthogonally on the other surface of the dielectric substrate so as to face the slots for the second frequency band. A pair of feeding microstrip lines for the second frequency band, and a substantially cross-shaped first frequency band arranged parallel to the dielectric plate and facing the slot for the first frequency band. Parallel to the parasitic element and the dielectric plate, and A slot-fed antenna with a second passive element for the frequency band that is arranged to face the second slot for the frequency band.

According to a third aspect of the present invention, a plurality of cross-shaped slots for the first frequency band are formed in a row, and the cross-shaped slots for the second frequency band higher than the first frequency band are formed. A metal plate having slots formed on both sides of each slot for each first frequency band along a row is provided with an antenna element substrate provided on one surface of a dielectric substrate, and a metal plate on the other surface of the dielectric substrate. A plurality of pairs of feeding microstrip lines for the first frequency band, which are orthogonally provided so as to face the slots for the second frequency band, and slots for the second frequency band on the other surface of the dielectric substrate. A plurality of pairs of feeding microstrip lines for the second frequency band, which are provided orthogonally so as to face each other, and are arranged so as to be parallel to the dielectric plate and to face the slot for the first frequency band. For a plurality of substantially cross-shaped first frequency bands A slot-fed antenna provided with a parasitic element and a plurality of parasitic elements for the second frequency band arranged in parallel with the dielectric plate and facing the slots for the second frequency band. .

The invention according to claim 4 is the invention according to claim 2 or 3.
In addition to the configuration described in, the slot for the first frequency band and the slot for the second frequency band are formed in a row,
Moreover, it is preferable that the branch portion of each slot is inclined by 45 degrees with respect to the central axis of the row.

The invention according to claim 5 is the invention according to claims 2 to 4.
In addition to the configuration described in any one of, in the slot for the first frequency band so that the parasitic element for the second frequency band is partially shaded on both sides of the parasitic element for the first frequency band. A slot for the second frequency band is preferably formed.

The invention according to claim 6 is the same as claims 1 to 5.
In addition to the configuration described in any one of the above ones, it may be expanded in a haunch shape so as to face the base side between the branches of the parasitic element for the first or second frequency band.

The invention described in claim 7 is from claim 1 to claim 5.
In addition to the configuration described in any one of 1, the tip of the branch portion of the parasitic element for the first or second frequency band may be formed in a mountain shape.

The invention described in claim 8 is from claim 1 to claim 5.
In addition to the configuration described in any one of above, a notch may be formed at the tip of the branch portion of the parasitic element for the first or second frequency band.

The invention described in claim 9 is from claim 1 to claim 5.
In addition to the configuration described in any one of 1. above, each branch portion of the parasitic element for the first or second frequency band may be formed in a star shape that narrows from the base portion to the tip.

According to a tenth aspect of the present invention, in addition to the structure according to any one of the first to fifth aspects, the tip of each branch portion of the parasitic element for the first or second frequency band has a convex shape. It may be formed in a shape.

In addition to the configuration according to any one of claims 1 to 5, the invention according to claim 11 is a straight line extending from the tip to the base of each branch of the parasitic element for the first or second frequency band. Shaped grooves may be formed.

In the twelfth aspect of the present invention, in addition to the configuration according to any one of the first to fifth aspects, the parasitic element for the second frequency band may have a rectangular, rhombic or circular shape. .

According to a thirteenth aspect of the present invention, in addition to the configuration according to any one of the first to fifth aspects, the parasitic element for the second frequency band has a rectangular shape, and projections are formed on opposite sides. May be respectively formed.

According to the present invention, a parasitic element having a cross shape that is parallel to a pair of feeding microstrip lines that are provided orthogonally so as to face a cross-shaped slot and that faces the slot. By placing
Since the branch portion of the parasitic element facing the one feeding microstrip line resonates, and the branch portion of the parasitic element facing the other feeding microstrip line resonates, the cross polarization discrimination is improved.

Further, by providing the slot and the parasitic element for the first frequency band and the slot and the parasitic element for the second frequency band, the parasitic element for the first frequency band becomes the first element. Since it resonates with the slot for the second frequency band and the parasitic element for the second frequency band resonates with the slot for the second frequency band, it is used as a shared antenna for the first frequency band and the second frequency band. can do.

Further, a slot for the first frequency band and a slot for the second frequency band are formed on one metal plate,
Since it has a simple configuration in which the feeding microstrip line and the parasitic element are arranged corresponding to each slot, it can be realized at low cost.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 (a) is a front view showing an embodiment of the slot feed type antenna of the present invention, and FIG. 1 (b) is a right side view of FIG. 1 (a). 9 (a) and 9 (b)
The same reference numerals are used for the same members as the conventional example shown in FIG.

This slot feed type antenna 20 has ± 4
It is a 5 degree polarization diversity directional antenna.

Reference numeral 2 denotes an antenna element substrate, in which a rectangular metal plate 4 in which a diagonal cross-shaped slot 3 is formed is provided on one surface (left side in FIG. 1B) of a rectangular dielectric substrate 5. It is a thing. On the other surface (right side in FIG. 1B) of the dielectric substrate 5, that is, on the back side of the antenna element substrate 2, a pair of feeding microstrip lines 6a and 6b are provided in a cross shape so as to face the slot 3. Power is supplied to the microstrip lines 6a and 6b for power supply. That is, the radiator is constituted by the slot 3 and the feeding microstrip lines 6a and 6b. This is to radiate electromagnetic waves of ± 45 ° polarization.

The surface of the antenna element substrate 2 (dielectric substrate 5
A plurality of (two in the figure, but not limited to) parasitic element plates 21 and 22 for guiding electromagnetic waves from the radiator to the surface direction are provided on one surface). However, the present invention is not limited to this).
It is supported to be parallel to.

In the parasitic element plate 21, a diagonally crossed parasitic element 23 made of metal is formed on one surface (left side in FIG. 1B) of the substantially rectangular dielectric substrate 10 as an antenna element substrate. It is provided so as to face the slot 3 of 2. In the parasitic element plate 22, a diagonal cross-shaped parasitic element 24 made of metal is provided on one surface (left side in FIG. 1B) of the substantially rectangular dielectric substrate 12 to form the antenna element substrate 2.
The slot 3 is provided so as to face the slot 3.

The antenna element substrate 2 and the parasitic element plates 21 and 22 are dielectric substrates provided with metal plates, but the present invention is not limited to this. May be. Also, this slot feed type 20
The shape of the antenna element substrate 2 is rectangular, but the present invention is not limited to this, and may be polygonal or circular.

The slot-fed antenna 20 is arranged at a high place such as a roof of a building or a steel tower so that the antenna element substrate 2 is vertical.

Next, the operation of the slot feed type antenna shown in FIGS. 1A and 1B will be described.

This slot feed type antenna 20 has a +45
When receiving an electromagnetic wave with a degree of polarization, two parasitic elements 2
3, 24 resonate with the incoming electromagnetic wave. At this time, the electric field resonating on the surfaces of the parasitic elements 23 and 24 is in the direction in which the plane of polarization coincides with the branches of the parasitic elements 23 and 24, that is, +4.
Since it resonates in the 5 degree direction and there are few electric field components resonating in the -45 degree direction, the cross polarization discrimination degree can be improved and the diversity effect is improved.

2A to 2I are shown in FIGS. 1A and 1B.
FIG. 9 is a front view showing a modified example of the parasitic element plate used in the slot-fed antenna shown in FIG.

Parasitic element plate 25-1 shown in FIG.
Is a star-shaped parasitic element 27-1 on the dielectric substrate 26-1 in which each branch of the diagonal cross is narrowed from the base to the tip.

The parasitic element plate 25-2 shown in FIG.
In this example, the parasitic element 27-2 having the convex shape at the tip of each branch of the diagonal cross is provided on the dielectric substrate 26-2.

Parasitic element plate 25-3 shown in FIG. 2 (c)
Includes a parasitic element 27-3 having a linear groove from the tip of each branch portion of the diagonal cross toward the base portion, and the parasitic element 27-3.
It is provided above.

Parasitic element plate 25-4 shown in FIG.
Is a parasitic element 27 having notches on the inside of the left end and the inside of the right end of each branch of the diagonal cross.
-4 is provided on the dielectric substrate 26-4.

Parasitic element plate 25-5 shown in FIG. 2 (e)
Is a parasitic element 27 having notches on the inside of the upper tip and on the inside of the lower tip of each branch of the diagonal cross.
-5 is provided on the dielectric substrate 26-5.

The parasitic element plate 25-6 shown in FIG.
Is a structure in which a parasitic element 27-6 in which the tip of each branch of the diagonal cross is formed in a mountain shape is provided on the dielectric substrate 26-6.

The parasitic element plate 27-7 shown in FIG.
Is a structure in which the parasitic element 27-7 in which the base of each branch of the diagonal cross is expanded in a haunch shape is provided on the dielectric substrate 26-7.

Parasitic element plate 25-8 shown in FIG.
In the base of each branch of the diagonal cross, a parasitic element 27-8 expanded in a haunch shape so as to face in the horizontal direction (horizontal direction in the drawing) is provided on the dielectric substrate 26-8. is there.

The parasitic element plate 25-9 shown in FIG. 2 (i).
In the base of each branch of the diagonal cross, a parasitic element 27-9 expanded in a haunch shape so as to face in the vertical direction (vertical direction in the figure) is provided on the dielectric substrate 26-9. is there.

Thus, the parasitic elements 23, 24, 27-
The electromagnetic fields resonating on the surfaces of the parasitic elements 23, 24, 27-1 to 27-9 are formed by forming the cross sections 1 to 27-9 in a substantially diagonal cross shape so as to face the slots 3 of the radiator. The direction of is diagonal, the cross polarization discrimination is improved, and the diversity effect is improved.

FIG. 3 is an external perspective view showing another embodiment of the slot feed type antenna of the present invention.

The slot feed type antenna 30 shown in FIG.
Are arranged in a row at a predetermined interval, and the plurality of radiators for the first frequency band (for example, 0.9 GHz band or 1.5 GHz band) and the radiators for the first frequency band are arranged on both sides of the radiator along the row. A plurality of parasitic element plates for the first frequency band on one band-shaped antenna element substrate 40 having a radiator for the second frequency band (for example, 2 GHz band) higher than the first frequency band. (See FIGS. 1A and 1B) 21, 22 and
A plurality of parasitic element plates 31 and 32 are arranged respectively.

FIG. 4 is a front view of an antenna element substrate used in the slot feed type antenna shown in FIG.

The antenna element substrate 40 shown in FIG. 4 is a strip-shaped dielectric substrate (eg, ceramic, glass, resin) 34.
And a plurality of cross-shaped slots 3 for the first frequency band are formed at a predetermined interval with an inclination of 45 degrees with respect to the longitudinal direction (inclination of 45 degrees with respect to the central axis L1 shown by the alternate long and short dash line). , Two cross-shaped slots 35 for the second frequency band are formed on each side of the slot 3 for the first frequency band along the row, and one surface of the dielectric substrate 34 (the surface of the paper in the figure). ) Provided on the metal plate (for example, gold-plated copper, silver-plated copper, copper, aluminum) 36 and the other surface of the dielectric substrate 34 (in this case, the back surface of the paper) to the slot 3 for the first frequency band. A pair of power supply microstrip lines 6a for the first frequency band, which are provided so as to face each other and cross each other;
6b and a pair of feeding microstrip lines 37a and 37b for the second frequency band, which are provided on the other surface of the dielectric substrate 34 so as to face and intersect the slots 35 for the second frequency band. It is composed of.

FIG. 5 is a front view of the slot-fed antenna shown in FIG. Note that, for simplification of description, the columns for supporting the parasitic element plate are omitted.

As shown in FIG. 5, the antenna element substrate 40 has a plurality of slots for the first frequency band on the slots 3 for the first frequency band (the number is not limited to two in the present embodiment). Parasitic element plates 21 and 22 are arranged, and the parasitic element plates 31 and 32 for the second frequency band are arranged on the slots 35 for the second frequency band, respectively. The parasitic element plates 31 and 32 for the second frequency band are arranged close to each other so that a part of them are hidden behind the parasitic element plates 21 and 22 for the first frequency band.

FIG. 6 is a front view of the parasitic element plate for the first frequency band.

The parasitic element plate 21 for the first frequency band is
As shown in FIG. 6, a parasitic element plate 23 made of a diagonally-crossed metal plate is provided on one surface of a substantially rectangular dielectric substrate 10. Parasitic element 2 for the first frequency band
2 also has the same structure as the parasitic element 21 for the first frequency band.

FIG. 7 is a front view of the parasitic element plate for the second frequency band.

As shown in FIG. 7, the parasitic element 31 for the second frequency band is provided with a parasitic element 39 made of a rectangular metal plate on one surface of a rectangular dielectric substrate 38. Is. The parasitic element 32 for the second frequency band also has the same structure as the parasitic element 31 for the second frequency band.

Electromagnetic waves in the first frequency band are fed to the feeding microstrip lines 6a and 6b of the slot feeding type antenna 30, and electromagnetic waves in the second frequency band are fed to the feeding microstrip lines 37a and 37b. Of the first frequency band, the parasitic elements 23 and 24 for the first frequency band resonate with the slot 3 for the first frequency band, and the parasitic element 39 for the second frequency band operates for the second frequency band. By resonating with the slot 35, it operates as an antenna for each frequency band.

The parasitic element for the first frequency band is shown in FIG.
You may have the shape similar to the modification shown to (a)-(h).

FIGS. 8A to 8F are front views showing modifications of the parasitic element plate for the second frequency band.

Parasitic element plate 31-1 shown in FIG.
Is a vertically long rectangular dielectric substrate 38-1 provided with a vertically long rectangular parasitic element 39-1.

The parasitic element plate 31-2 shown in FIG. 8B.
Is a diamond-shaped parasitic element 3 on a rectangular dielectric substrate 38-2.
9-2 is provided.

The parasitic element plate 31-3 shown in FIG. 8C.
Is a vertically-long rectangular dielectric substrate 38-3 having a rectangular shape and provided with parasitic elements 39-2 having protrusions formed on both upper and lower sides facing each other.

The parasitic element plate 31-4 shown in FIG.
Is a horizontally long rectangular dielectric substrate 38-4 provided with a horizontally long rectangular parasitic element 39-4.

The parasitic element plate 31-5 shown in FIG.
Is a circular parasitic element 3 on a rectangular dielectric substrate 38-5.
9-5 is provided.

The parasitic element plate 31-6 shown in FIG.
Is a rectangular oblong dielectric substrate 38-6 having a rectangular shape and provided with a parasitic element 39-6 having protrusions formed on the opposite left and right sides, respectively.

The parasitic element plate for the second frequency band may have the same shape as the modification shown in FIGS. 2 (a) to 2 (h).

Parasitic element plate 2 for these first frequency bands
1, 22, 25-1 to 25-9 and the parasitic element plates 31, 32, 31-1 to 31-6 for the second frequency band may be configured by using a printed circuit board, and a metal plate may be omitted. The feed element formed in the shape may be supported on the antenna element substrate by a pillar made of an insulator.

In the above, by forming the parasitic element for the first frequency band in the shape of an oblique cross, it is possible to obtain a slot-fed antenna with a planar structure which is inexpensive and easy to manufacture. In addition, each antenna element is 4
Since it is inclined 5 degrees and a part of the parasitic element plate for the second frequency band overlaps with the parasitic element plate for the first frequency band,
It is possible to store the antenna element in a place where the longitudinal direction is short.

[0073]

In summary, according to the present invention, the following effects can be obtained. (1) It is possible to provide a slot-fed antenna with an improved diversity effect. (2) It is possible to provide an inexpensive slot-fed antenna that shares two frequencies.

[Brief description of drawings]

FIG. 1A is a front view showing an embodiment of a slot-fed antenna of the present invention, and FIG. 1B is a right side view of FIG.

2A to 2I are front views showing modified examples of a parasitic element plate used in the slot-fed antenna shown in FIGS. 1A and 1B.

FIG. 3 is an external perspective view showing another embodiment of the slot-fed antenna of the present invention.

4 is a front view of an antenna element substrate used in the slot-fed antenna shown in FIG.

5 is a front view of the slot-fed antenna shown in FIG.

FIG. 6 is a front view of a parasitic element plate for the first frequency band.

FIG. 7 is a front view of a parasitic element plate for the second frequency band.

8A to 8F are front views showing modifications of the parasitic element plate for the second frequency band.

9 (a) is a front view showing a conventional example of a slot-fed antenna, and FIG. 9 (b) is a right side view of FIG. 9 (a).

[Explanation of symbols]

2, 40 Antenna element substrate 3, 35 Slots 6a, 6b, 37a, 37b Microstrip lines for feeding 23, 24, 39 Parasitic elements

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shinsuke Murano             1-6-1, Otemachi, Chiyoda-ku, Tokyo             Standing Wire Co., Ltd. (72) Inventor Masakazu Shibata             1-6-1, Otemachi, Chiyoda-ku, Tokyo             Standing Wire Co., Ltd. F-term (reference) 5J021 AA01 AA05 AA07 AA13 AB05                       CA03 HA06 HA10 JA03 JA05                 5J045 AA03 AA12 AA14 AB06 BA01                       CA01 DA06 FA01 GA02 GA04                       HA03 JA11 NA03                 5J046 AA04 AA19 AB08 AB10 PA07

Claims (13)

[Claims] 1. A metal plate on which a cross-shaped slot is formed is orthogonal to an antenna element substrate provided on one surface of a dielectric substrate and the other surface of the dielectric substrate so as to face the slot. Slot feeding type characterized by including a pair of feeding microstrip lines provided as a pair, and a substantially cross-shaped parasitic element arranged in parallel with the dielectric plate and facing the slot. antenna. 2. A cross-shaped slot for a first frequency band and a cross-shaped slot for a second frequency band higher than the first frequency band so as to be located on both sides of the slot for the first frequency band. The metal plate on which is formed is provided orthogonal to the antenna element substrate provided on one surface of the dielectric substrate and the other surface of the dielectric substrate so as to face the slot for the first frequency band. A pair of feeding microstrip lines for the first frequency band, and a second frequency band orthogonally provided on the other surface of the dielectric substrate so as to face the slot for the second frequency band. A pair of feeding microstrip lines for power supply, and a substantially cross-shaped parasitic element for the first frequency band, which is arranged parallel to the dielectric plate and facing the slot for the first frequency band , Parallel to the dielectric plate, and the second circumference A slot-fed antenna, comprising: a parasitic element for a second frequency band, which is arranged so as to face a slot for a wave number band. 3. A plurality of cross-shaped slots for a first frequency band are formed in a row, and a cross-shaped slot for a second frequency band higher than the first frequency band is provided for each first frequency. An antenna element substrate having metal plates formed along the rows on both sides of the band slot and provided on one surface of the dielectric substrate, and a slot for the first frequency band on the other surface of the dielectric substrate. A plurality of pairs of feeding microstrip lines for the first frequency band, which are provided orthogonally so as to face each other, and to face the slot for the second frequency band on the other surface of the dielectric substrate. A plurality of pairs of feeding microstrip lines for the second frequency band, which are provided orthogonally to each other, and a plurality of the plurality of substantially arranged parallel to the dielectric plate and facing the slot for the first frequency band. Parasitic parasitic element for the first frequency band And a plurality of parasitic elements for the second frequency band arranged in parallel with the dielectric plate and facing the slots for the second frequency band. antenna. 4. A slot for a first frequency band and a slot for a second frequency band are formed in a line, and
4. The slot-fed antenna according to claim 2, wherein the branch portion of each slot is inclined by 45 degrees with respect to the central axis of the row. 5. The second frequency band is provided in the slot for the first frequency band so that the parasitic elements for the second frequency band are partially shaded on both sides of the parasitic element for the first frequency band. The slot-fed antenna according to any one of claims 2 to 4, wherein a slot for use is formed. 6. The slot-fed antenna according to any one of claims 1 to 5, wherein the slot-fed antenna is expanded so as to face the base side between the branches of the parasitic element for the first or second frequency band. . 7. The slot feed type antenna according to claim 1, wherein a tip of a branch portion of the parasitic element for the first or second frequency band is formed in a mountain shape. 8. The slot-fed antenna according to claim 1, wherein a notch is formed at a tip of a branch portion of the parasitic element for the first or second frequency band. 9. The slot feed type according to claim 1, wherein each branch of the parasitic element for the first or second frequency band is formed in a star shape that narrows from the base to the tip. antenna. 10. The slot-fed antenna according to claim 1, wherein a tip of each branch of the parasitic element for the first or second frequency band is formed in a convex shape. 11. The slot feed type according to claim 1, wherein a linear groove is formed from the tip to the base of each branch of the parasitic element for the first or second frequency band. antenna. 12. The slot-fed antenna according to claim 1, wherein the parasitic element for the second frequency band has a rectangular shape, a rhombic shape, or a circular shape. 13. The slot-fed antenna according to claim 1, wherein the parasitic element for the second frequency band has a rectangular shape and protrusions are formed on opposite sides.