JP2003037423A - Surface mounting antenna, and communication system loaded with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small surface mounting antenna having small height, high radiation efficiency and a wide band, and to provide provide a communication system with the surface mounting antenna. SOLUTION: A radiating electrode 2A, elongated with a width that becomes narrower from one edge to the other elongated edge, is formed on an upper face (face C) and an adjoining side face (face D) of a rectangular parallelepiped dielectric base 1. In a central area or a top narrow area and a base wide area of the radiating electrode 2A, each meandering type radiating electrode 20m is formed and connected or capacitively coupled, with a grounding electrode 3 formed on an edge face (face E) of the base, while one narrow side thereof being opened to an edge face (face F). A power feed electrode 4 driving the radiating electrode 2A in a non-contacted state is formed on a side face (face B) of the base, in the surface mounting antenna.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-mounted antenna (hereinafter sometimes simply referred to as an antenna) suitable for a microwave wireless communication device such as a mobile phone and a wireless LAN (local area network). Is.

[0002]

2. Description of the Related Art In microwave radio communication devices, especially mobile communication devices such as mobile phones, monopole antennas, microstrip antennas and the like are generally used as antenna elements in order to reduce the size and height. Among them, the structure and principle of the microstrip antenna, which has been increasingly applied recently, is described in detail in the Antenna Engineering Handbook (p109-111 Ohmsha, edited by the Institute of Electronics, Information and Communication Engineers).

At present, a surface mount type is mainly used as a microstrip antenna. For example, Japanese Laid-Open Patent Publication No. 9-153.
No. 734 and Japanese Patent Laid-Open No. 10-107535. As shown in FIG. 10, this antenna has, for example, a meandering radiation electrode 91 formed on the upper surface of a substantially rectangular parallelepiped base body 90, and is directly connected to the radiation electrode 91 by hanging from the side surface 92 of the base body to the upper surface or by capacitive connection. Feeding electrode 93
Power is supplied from the power supply terminal 94. In terms of an equivalent circuit, a radiation resonance R and an inductance L of the radiation electrode and a capacitance C formed between the open end of the radiation electrode and the ground electrode constitute a parallel resonance circuit. When operating this as an antenna, one side surface of the antenna base 9
By disposing the ground terminal 95 and the power supply terminal 94 provided in 2 on the ground conductor 97 and the power supply line 98 of the circuit board 96, respectively, and by passing the high frequency signal from the lower surface side through the power supply line, the high frequency signal is generated. Electromagnetic waves are radiated from the radiation electrode due to parallel resonance. In addition, as the shape of the radiation electrode, in addition to the meander shape, a bent shape such as an L-shape, a U-shape, or a crank shape is used to reduce the size.

[0004]

An antenna used in a portable communication device is required to have a small size, a low profile, good radiation efficiency, no directivity and a wide band.
In this respect, the conventional surface mount antenna tends to deteriorate in the antenna characteristics as the size and height of the antenna are further reduced, and simply the size and height of the antenna cannot be reduced. Therefore,
The inventors of the present application have previously proposed a surface-mount antenna having radiation electrodes that form a ladder-type parallel resonant circuit for the purpose of obtaining a high-gain, wide-band antenna with a reduction in size and height ( Japanese Patent Application No. 2001-45354, etc.). That is, as shown in FIG. 9, this antenna continuously and / or stepwise narrows the width from at least one end of the base to at least the upper surface of the base 80 having a substantially rectangular parallelepiped shape. The radiation electrode 81 is formed to extend while one end of the radiation electrode 81 is connected to the ground electrode 85 provided on the end surface 82 of the base body 80 and grounded.
A power supply electrode 83 is formed in a non-contact manner at a side surface position where impedance matching is performed in the middle of. This antenna does not have a ground electrode on most of the bottom surface of the base,
When mounting on the circuit board 86, the ground electrode 85 and the dummy electrode (not shown) on the end surface of the base and the ground conductor 8 of the circuit board 86.
7, 87 'are respectively connected as shown. The greatest feature of this antenna is that the radiation electrode 81 has a non-uniform width, and multiple resonance circuits are equivalently formed corresponding to this shape to cause multiple resonance.

Recently, these dielectric antennas are often used as chip antennas for wireless LAN and GPS (Global Positioning System), and it is necessary to mount them in a very small space such as a mobile phone. Therefore, even in the above antenna structure, for example, the length is 10 mm.
Hereafter, there is a demand for an antenna having a width and a thickness of about 3 to 2 mm, which is further reduced in size and height. However, when the size of the substrate is limited, it becomes difficult to adjust the frequency, the radiation efficiency is poor, the gain is lowered, and the bandwidth is lowered.

Therefore, the present invention relates to the improvement of the above-mentioned already proposed antenna, which realizes further downsizing and height reduction, widens the range of frequency adjustment, improves the radiation gain and widens the bandwidth. The purpose is to provide an antenna.
Another object of the present invention is to provide a communication device in which this antenna is mounted on a circuit board so as to suppress a decrease in gain.

[0007]

According to the present invention, at least one surface of a rectangular parallelepiped base made of a dielectric or magnetic material is continuously and / or stepwise from one end of the base to the other end in the longitudinal direction. A radiation electrode that extends substantially narrower in width, and one end of the radiation electrode is connected or capacitively coupled to a ground electrode provided on the end surface of the base body, and is coupled to the radiation electrode in contact or non-contact. It is a surface-mounted antenna in which a feeding electrode is formed on the surface of a base body, and is a surface-mounted antenna in which a central region of the radiation electrode is formed in a meandering bent portion.

Further, according to the present invention, at least one surface of a rectangular parallelepiped base made of a dielectric or magnetic material is continuously and / or continuously formed from one end of the base toward the other end in the longitudinal direction.
Alternatively, a radiating electrode extending gradually narrowing gradually is formed, and one end of the radiating electrode is connected or capacitively coupled to a ground electrode provided on the end surface of the base body, and is in contact with or not in contact with the radiant electrode. A surface mount antenna in which feed electrodes to be coupled are formed on the surface of a substrate, wherein a narrow region and a wide region of the radiation electrode are formed in meandering bent portions.

In the antenna of the present invention, the radiation electrode has a shape in which the width is narrowed toward the open end of the tip, so that the bandwidth can be expanded by multiple resonance of a plurality of resonance circuits. At this time, by forming a meandering bent portion on the radiation electrode, it is possible to extend the length of the radiation electrode, increase the inductance, and reduce the size of the substrate. However, in general, when a bent portion such as meander is provided, the conductor loss increases and the radiation efficiency (gain) is reduced. Considering the area where the bent portion is provided, the wide area on the base side of the radiation electrode has a larger current intensity and a larger reduction in radiation efficiency than the narrow area on the tip side. Bandwidth is greatly improved. On the other hand, in the narrow region on the front end side, since the current easily flows and the conductor loss is small, the decrease in the radiation efficiency is suppressed but the increase in the bandwidth is small. Therefore, in order to obtain both radiation efficiency and bandwidth characteristics moderately, it is necessary to provide meander-shaped bends in the central region, or to appropriately bend meander-shaped bends at both ends of the narrow and wide regions. It is effective to provide a section.
As described above, it is possible to obtain an antenna having a wide bandwidth and improved radiation efficiency.

Further, the meandering bent portion has no flexibility for downsizing and frequency adjustment unless it has a length of at least 1/15 of the total length of the radiation electrode. The ratio of the bent portion to the entire length of the radiation electrode varies depending on the position where the bending portion is provided, but it is preferably about half of the entire length of the radiation electrode, and at most 4 /
Up to about 5. For example, when a center frequency of 2.45 GHz is obtained using a radiation electrode with a total length of 10 to 15 mm, a meandering bent portion should be provided in the central portion in a region of 4 to 6 mm or 5 mm from the tip and 1 mm from the ground side. Can be said to be desirable. Furthermore, it is desirable to round or chamfer the corners of the meandering bent portion so that the corners are uniformly chamfered. As a result, the line width of the bent portion and the current flow are substantially uniform and the impedance discontinuity is improved, so that the reflection loss at the bend angle is suppressed and the gain is improved. Further, if the number of meandering electrode lines is 2n + 1 and is an odd number, the amount of current cancellation is not completely offset, which is desirable for gain improvement. Further, a second ground electrode facing the tip of the radiation electrode via a gap can be provided on the other end face of the base. As a result, capacitive loading is achieved, and the resonance frequency can be easily adjusted by downsizing and adjusting the gap.

Further, according to the present invention, when the above-mentioned surface mount antenna is mounted on a circuit board, the longitudinal direction of the base body on which the radiation electrode extends is parallel to the boundary line of the ground conductor end of the circuit board. Moreover, it is a communication device in which the tip end side of the radiation electrode is arranged away from the ground conductor and such a circuit board is mounted. This is suitable for a communication device mounted on a mobile phone, a headphone, a personal computer, a notebook computer, a digital camera or the like as a surface mount antenna.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the surface mount antenna of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a surface mount antenna showing a first embodiment, and FIG. 2 is a development view of FIG. This antenna 1A includes a rectangular parallelepiped base 1 made of a dielectric material such as ceramics and resin, a radiation electrode 2A formed on the upper surface and adjacent side surfaces thereof, and connected to one end of the radiation electrode to cover an end surface of the base. Formed ground electrode 3
And a feeding electrode 4 provided on the side surface in the longitudinal direction of the base. The radiation electrode 2A basically has a tapered shape extending continuously and / or stepwise in the longitudinal direction while narrowing the width substantially from the wide region at the base, and the substantially central region is formed into a meandering bent portion 20c. Is forming. The radiation electrode 2A has a side surface (D) adjacent to the radiation electrode 20 provided on the upper surface (C surface) of the base, as shown in a developed view in FIG.
The radiation electrodes 21 are continuously formed on the surface) and are integrated on the ridgeline of the substrate. The tip of the radiation electrode is an open end 15, and the other end on the root side is connected to the ground electrode 3 on the end face (E face). The connection here may be in the form of non-contact capacitive coupling.

The feeding electrode 4 is formed at an arbitrary position on the side surface of the base body that impedance-matches with the radiation electrode (usually 50Ω) and is excited in a non-contact manner through a capacitor to facilitate matching. May extend to the upper surface of the substrate, or may be directly connected to the radiation electrode. The ground electrode 3 may be provided so as to surround an end portion including one end surface (E surface) of the base body 1, but the extension electrode 30 is also formed at least on the lower surface (A surface) and connected to the ground conductor of the circuit board. It can be so. Further, the feeding electrode 4 is also extended to the lower surface (A surface) side of the base body to provide an extension electrode 40 for soldering, and a fixed electrode 50 for reinforcing the attachment to the circuit board.

A second embodiment of the surface mount antenna of the present invention is shown in the perspective view of FIG. 3 and the developed view of FIG. It should be noted that the same components as those of the antenna of FIG. The antenna 1B of this embodiment is provided with a meandering bent portion 22t in a narrow region of the radiation electrode 22 and a meandering bent portion 22r in a wide region of the radiation electrode 22. As shown in the development view of FIG. 4, the radiation electrode 2B has a radiation electrode 22 provided on the upper surface (C surface) of the base body and a meandering bent portion similar to the tip side and the root side on the adjacent side surface (D surface). The radiation electrode 23 is provided with 23t and 23r. Further, here, the bent portions 22t and 23t on the tip side form the slits 11 as shown in the figure to form nine electrode lines 12, and the bent portions 22r and 23r on the root side form two slits 11. The number of electrode lines 12 is two.
Although the minimum length is used here in order to suppress the reduction in radiation efficiency while expanding the bandwidth, it is desirable to use an odd number of electrode lines in consideration of the following reasons.

Next, the function and effect of the radiation electrode will be described. First, the basic shape of the radiation electrode is such that the electrode length in the direction perpendicular to the flow of the high-frequency current (longitudinal direction of the substrate), that is, the width is not constant, but gradually decreases as it approaches the open end side. did. The high-frequency current supplied from the power supply source via the power supply electrode resonates at a frequency determined by the capacitance of the capacitor formed between the inductance of the radiation electrode and the ground, and is radiated as space electromagnetic energy. At this time, it becomes a current distribution mode in which the ground electrode and the open end serve as nodes and antinodes. If the width of the radiation electrode is constant, there is only one current distribution mode. However, since the width of the radiation electrode is not constant as in the present invention, and the electrode arrangements shown in the figure make it possible to provide a plurality of antennas. The resonant circuit of is formed equivalently. At this time, the resonance frequencies of the respective resonance circuits are generated so close to each other that a plurality of resonances continuously exist, and as a result, a wide-band resonance characteristic having a widened bandwidth is obtained. Further, as shown in the development view of FIG. 2, when the radiation electrode is formed not only on the upper surface of the base body but also on the adjacent side surfaces, the size is further reduced, and radiation directivity closer to non-directionality can be obtained.

Further, according to the present invention, the meandering bent portion 20c is provided in the central region of the radiation electrode, or the meandering bent portion 22t is provided in the narrow region on the tip side and the wide region on the root side, respectively. 22r is provided.
Thereby, first, the inductance component L of the radiation electrode is increased, and the size can be further reduced. Further, when the bent portion is provided on the root side, the current intensity is large in a wide region, and the amount of current flowing in the bent portion alternately is large. Therefore,
Since the resistance R is large and the conductor loss is also large, the power loss is large and the radiation efficiency is reduced. However, on the other hand, since the bandwidth is proportional to RL ^0.5 , the bandwidth increases as L and R increase. Further, when the bent portion is provided on the tip side, it is possible to suppress the decrease in radiation efficiency and adjust to a desired frequency, but an increase in bandwidth cannot be expected very much. Since the current easily flows on the tip side, it is advantageous in that the inductance component can be gained and the radiation efficiency is not hindered. From the above, if the position where the meandering bent portion is provided is set to the central portion of the radiation electrode, the advantages of moderately widening the band and improving the gain can be enjoyed. On the other hand, by appropriately providing both the narrow tip side and the wide root side, it is possible to obtain an antenna in which banding is expanded and radiation efficiency (gain) is not low. Further, the approximate frequency can be adjusted on the base side where the frequency adjusting effect is high, and the fine adjustment can be performed on the tip side where the frequency fine adjustment is easy.

In the meandering bent portion, the electric currents in the line direction alternately flow in opposite directions, so that the electromagnetic fields emitted into the space cancel each other out, and the emitted electromagnetic field becomes small as a whole of the bent portion. At this point, the number of electrode lines is 2
By canceling the current by reducing the number to n + 1 and odd-numbered lines. In the above-described example, the slits 11 are appropriately provided so that an odd number of electrode lines 12 are provided. In addition, the meandering radiation electrodes 20c, 22
The regions in which t and 22r are provided can be appropriately set based on the relationship between the substrate size and the desired frequency, etc., but according to the following comparative study, the effect is not expected so much within approximately 1/15 of the total length of the radiation electrode. I think about 1/5 to 4/5 is good.

Next, manufacturing of the antenna of the embodiment will be described. Usually, the base of the antenna is made of ceramics, and a plurality of rectangular parallelepiped chips are cut out from the ceramic block and ground to a predetermined size. Next, a plurality of these chips are arranged side by side in a jig, and Ag electrodes are formed by screen printing on each surface of the many chips. After forming an electrode on each surface, it is baked at 850 ° C. to obtain a chip-shaped antenna element. The electrode to print is the ground electrode 3 on the A side.
And an extension electrode of the feeding electrode 4 and an electrode for fixing (soldering),
The feeding electrode 4 is formed on the B surface, the radiation electrode 20C is formed on the C surface, the radiation electrode 21C is formed on the D surface, and the ground electrode 3 is formed on the E surface. When the second ground electrode is provided, the electrode is also formed on the F surface.

Next, the third surface mount antenna of the present invention will be described.
Is shown in the perspective view of FIG. It should be noted that the same components as those of the antenna of FIG.
The antenna 1C of this embodiment is a meandering radiation electrode 2
It is characterized in that the bent portion of 4c has a roundness 13 to connect the electrode lines. A similar meandering radiation electrode is also provided on the D surface. In the meandering radiating electrode of FIG. 1, the straight line portion and the bent portion of the line were connected with unequal width. This results in a discontinuous change in the impedance of the electrode line, and a part of the traveling wave is reflected due to the discontinuity. Furthermore, when paying attention to the corners, the inner path length is shorter than the outer path length, and as a result, a strong current easily flows toward the inner side, and impedance discontinuity occurs here. Therefore, the chamfering with rounded corners or the chamfering with the corners cut off improves the impedance discontinuity and suppresses the occurrence of reflection loss at the corners. As a result, the transmission loss of the resonance current flowing through the radiation electrode of the antenna can be reduced, and the gain is improved. Further, in this example, the round chamfer 14 is provided by connecting the bending angle of the bent portion not only on the outer diameter side but also on the inner diameter side with an arc. Therefore, compared to the case where only the outer diameter side is rounded, the electrode line width at the bend corner becomes more equal, and the impedance discontinuity at the bend corner of the electrode line decreases, so the occurrence of reflection loss is further suppressed. To be done. Further, in the present embodiment, the ground electrode 3 is not provided on the end face of the base body but on the side of the D face, and the extension electrode 30 is formed on the A face. With such a configuration, the path length of the electrode, that is, the inductance L can be increased, and the desired frequency can be realized by using a smaller antenna.

A fourth embodiment of the surface mount antenna of the present invention is shown in FIG. The same components as those of the antenna of the above embodiment are designated by the same reference numerals, and the description thereof will be omitted. In this example, a second ground electrode is provided via a gap G at the end of the base body facing the open end of the tip of the radiation electrode. The ground electrode 5 is formed over the end face (F face) of the base 1 and the four faces surrounding it. As a result, capacitance can be loaded between the open end 15 of the radiation electrode 26 and the ground conductor, and the capacitance can be stabilized to facilitate frequency adjustment. In addition, it is suitable for downsizing because the desired frequency can be obtained with a small inductance as much as the capacity can be gained in the gap portion, and the generated electromagnetic field can be concentrated in the vicinity of the gap portion, so there is little influence on the surroundings or from the surroundings. There is also an effect. The third,
It goes without saying that the meandering radiation electrode of the fourth embodiment is not limited to the one shown in FIG.

Next, a structure for mounting the above surface mount antenna on a circuit board will be described. FIG. 7 shows a state in which the antenna 1A described in FIG. 1 is mounted on the circuit board 6. Of course, in this figure, only the antenna arrangement is shown and the other parts are not shown. The antenna 1A is a circuit board 6
On the exposed portion 65, the end boundary line 63 of the ground conductor 62 and the longitudinal direction of the base body are parallel to each other, and the open end 15 of the radiation electrode 2A is arranged so as to be away from the ground conductor 62. As a result, the high frequency signal supplied from the power supply 60 is supplied to the power supply electrode 4 via the power supply line 61 to excite the radiation electrode, and electromagnetic waves are radiated into space from the open end of the radiation electrode tip.

Conventionally, the antenna element is often arranged vertically (longitudinal direction) with respect to the ground conductor. In such a case, it goes without saying that the dead space becomes large and the degree of freedom in design is low. By arranging them in the horizontal direction (parallel), the occupied area is remarkably reduced, and the degree of freedom and density of the mounting layout can be increased to save space. On the other hand, when they are placed in parallel, it is necessary to compensate for the gain reduction compared to the vertical placement. However, as shown in this point, a slight gap is present between the end boundary line 63 of the ground conductor 62 and the antenna base. The gain can be improved by providing. The gap is a few millimeters, eg 1
Since the effect appears at about 3 mm, it can be set within the range where the occupied area is allowed.

Further, as an electrical interaction with the circuit board, a mirror image current is generated in the ground conductor of the board due to the resonance current of the antenna, and when the mirror image current and the current flowing through the substrate have opposite phases, electromagnetic radiation from the antenna is generated. May be hindered, resulting in a decrease in gain and a shift in resonance frequency. At this point, if the open end of the radiation electrode through which the resonance current flows most strongly is arranged at the position farthest from the ground conductor, the electric field can be induced at a position away from the ground conductor, and the mirror image current can be made as weak as possible. Also,
Since most of the back surface of the antenna does not have a ground electrode, it is possible to prevent the mirror image current from flowing through the ground conductor. By mounting the circuit board on which the antenna is mounted in a mobile phone or a personal computer schematically shown in FIG. 6, it can be used as a communication device having a Bluetooth function (see FIG. 8).

The first and second embodiments of the present invention will be described below.
A characteristic comparison between the antenna of FIG. 9 and the antenna of FIG. 9 previously proposed by the inventors of the present application will be described below. Here, the first embodiment is shown in FIG.
3 is a case where a meandering bent portion is provided in the central portion shown in FIG. 3, and Example 2 is a case where meandering bent portions are provided on the tip side and the root side shown in FIG. 3, respectively. This is a case where the bending angle of the bent portion shown in FIG. Comparative Example 1 is a case where the meandering bent portion shown in FIG. 9 is not provided. First, the antenna substrate is made of Al _{2 with} a relative permittivity εr = 8.
10 mm length x 3 width using O ₃ based ceramic material
mm × thickness 2 mm. By design, the center frequency of the propagation frequency is 2.45 GHz ± 10 MHz and the bandwidth is 90.
Each electrode was set with the goal of satisfying performances such as MHz, 3.5% of specific band, radiation efficiency of 60% or more, and voltage standing wave ratio (VSWR) of 3 or less. The electrodes were printed using the same process using Ag electrode material. Further, the antennas were arranged on the circuit board in the same manner as in FIG.

As the characteristic evaluation items, the bandwidth, directivity and gain characteristics (radiation efficiency) at the voltage standing wave ratio (VSWR) 3 were measured and evaluated. The VSWR was measured by connecting a network analyzer to the power supply terminal and measuring the impedance seen from the terminal side. When measuring the gain, when the radiated power from the antenna under test used as the transmitting antenna in the anechoic chamber is received by the receiving reference antenna and the receiving power and the reference antenna are used as the transmitting antennas. Was evaluated as the ratio to the received power. Regarding the directivity, the antenna element under test was mounted on a rotary table, and while rotating, the intensity of the radiated electric field was measured for the gain at each rotation angle by the same procedure as the measurement of the gain. Regarding the directivity and the possibility of adjusting to the center frequency, relative evaluations of ○, Δ, and × were made. The results are shown in Table 1.

[0026]

[Table 1]

Regarding the directional characteristics, in both the embodiment and the comparative example, the gains of the three axes of X, Y and Z are almost circular, and non-directional characteristics having no directivity were obtained. Regarding the bandwidth, the target value was about 90 MHz in Comparative Example 1, but in each of the Examples, a value significantly exceeding the target value could be obtained. As for the radiation efficiency, although the examples are slightly lower than those of the comparative examples, the characteristics satisfying the target value of 60% are obtained. The frequency decreases as the inductance increases by increasing the meandering bent portion. In Example 1, when the meandering bent portion is provided at 1/15 of the length of the radiation electrode, the center frequency becomes high and it is difficult to set the target value, and the meandering bending portion is provided up to 3/5 of the length of the radiation electrode. In this case, the center frequency is lower than the target frequency. These facts suggest that it is desirable to provide the meandering bent portion, but the length thereof has an appropriate desirable range. As described above, in any of the examples, the center frequency can be adjusted by providing the meandering bent portion in the range corresponding to the frequency.
In addition, although the radiation efficiency is slightly lowered in Examples 1, 2 and 3, the bandwidth is significantly widened. Therefore, it was confirmed that by using the radiation electrode shape of the present invention, it is possible to obtain a small antenna with a wide band and high efficiency at a desired center frequency.

In another embodiment of the present invention, the base material may be a magnetic material, a resin material, or a laminated substrate of these materials.
The bent portion of the meandering radiation electrode may have a crank shape that is irregularly bent. Further, the width of the electrode line and the width dimension of the slit can be appropriately changed. Further, it is effective to trim the radiation electrode or the substrate for widening the bandwidth or adjusting the frequency. For example, if the tip portion of the radiation electrode in FIG. 1 is formed in the parallel portion 16 and this portion is ground in parallel, frequency adjustment is easy and effective. The radiation electrode may have various shapes such as a trapezoidal shape, a stepped shape, and a curved shape, but may be any shape that extends continuously and / or stepwise in the longitudinal direction while substantially narrowing the width. Further, it is not always necessary to continuously form the ground electrode on one end side of the radiation electrode,
There is no capacitive coupling that is discontinuous, and it suffices if it is finally grounded. The ground electrode should cover at least its end face and be connected to the ground face so as to be grounded. However, in order to obtain the effect of suppressing the emission of the electric field from the end face of the substrate, the end face and its surroundings at the end of the substrate. It is advisable to form so as to surely cover the four surfaces.

[0029]

According to the present invention, the size and height can be reduced, the radiation efficiency and the bandwidth can be uniformly improved, the frequency can be adjusted relatively easily, and the manufacturing is advantageous and inexpensive.
Moreover, a higher performance surface mount antenna was obtained. Further, when this antenna is mounted on a circuit board, the occupied area can be reduced and the gain can be improved. Therefore, when this is mounted on a communication device such as a mobile phone or a small information terminal, it can contribute to downsizing of the device and have stable communication performance regardless of the posture of the device.

[Brief description of drawings]

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

2 is a development view of the antenna of FIG. 1. FIG.

FIG. 3 is a perspective view of an antenna showing a second embodiment of the present invention.

4 is a development view of the antenna of FIG.

FIG. 5 is a perspective view of an antenna showing a third embodiment of the present invention.

FIG. 6 is a perspective view of an antenna showing a fourth embodiment of the present invention.

FIG. 7 is a mounting view showing a state in which the antenna of the present invention is mounted on a circuit board.

FIG. 8 is a conceptual diagram of mounting the antenna of the present invention on a communication device.

FIG. 9 is a perspective view of an antenna showing a comparative example with respect to the embodiment of the present invention.

FIG. 10 is a perspective view showing an example of a conventional surface mount antenna.

[Explanation of symbols]

1A, 1B, 1C, 1D: Surface mount antennas 1, 80, 90: Dielectric substrates 2A, 2B, 2C, 2D, 20, 21, 22, 23, 2
4, 26, 81, 91: Radiation electrodes 3, 85: Ground electrodes 4, 83, 93: Feed electrode 5: Second ground electrodes 6, 86, 96: Circuit board 11: Slit portion 12: Meander-shaped radiation electrode Lines 13 and 14: Round chamfer of bent portion 15: Open end of radiation electrode 16: Parallel portions 20C, 21C, 24C, 26C of radiation electrode tip: Central regions 22t, 23t, 24t of radiation electrode: width of radiation electrode Wide regions 22r, 23r: Narrow region of the radiation electrode 30: Extension electrode of the ground electrode, 40: Extension electrode of the feeding electrode 50: Fixed electrode 60 for reinforcing the attachment to the substrate 60: Feeding power source, 61, 88, 98: Feed line, 62: ground conductor 63: boundary line of ground conductor, 64: extension of ground conductor, 6
5: exposed portion 82 of circuit board: end surface of dielectric substrate, 87, 87 ', 97: ground conductor of circuit board 92: one side surface of dielectric substrate, 94: power supply terminal

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01Q 9/42 H01Q 9/42 F term (reference) 5J046 AA04 AA07 AB13 PA04 PA07 5J047 AA04 AA07 AB13 FD01

Claims (7)

[Claims] 1. A width of a rectangular parallelepiped base made of a dielectric or magnetic material is reduced continuously and / or stepwise from one end of the base to the other end in the longitudinal direction on at least one surface of the base. A radiating electrode that extends while forming one end of the radiating electrode connected to or capacitively coupled to a ground electrode provided on the end face of the base, and forming a feeding electrode on the surface of the base that connects the radiative electrode in contact or non-contact. A surface-mounted antenna, wherein a central region of the radiation electrode is formed in a meandering bent portion. 2. The width of at least one surface of a rectangular parallelepiped base made of a dielectric or magnetic material is reduced continuously and / or stepwise from one end of the base toward the other end in the longitudinal direction. A radiating electrode that extends while forming one end of the radiating electrode connected to or capacitively coupled to a ground electrode provided on the end face of the base, and forming a feeding electrode on the surface of the base that connects the radiative electrode in contact or non-contact. A surface-mounted antenna, wherein the radiation electrode has a narrow region and a wide region formed in a meandering bent portion. 3. The surface mount antenna according to claim 1, wherein the meandering bent portion of the radiation electrode is provided in a region within 4/5 of the entire length of the radiation electrode. 4. The surface mount antenna according to claim 1, wherein the bent corner of the radiation electrode is rounded or chamfered. 5. The number of meander-shaped electrode lines of the radiation electrode is set to 2n + 1.
The surface mount antenna according to any one of 1. 6. The second ground electrode facing the tip of the radiation electrode with a gap provided on the end face of the other end of the base body according to any one of claims 1 to 5. Surface mount antenna. 7. A communication device in which the surface mount antenna according to claim 1 is mounted on a circuit board,
The communication is characterized in that the longitudinal direction of the base on which the radiation electrode extends is arranged in parallel with the boundary line of the ground conductor end of the circuit board, and the tip end side of the radiation electrode is arranged away from the ground conductor. machine.