JP2006033560A - Antenna, and radio communications equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-mounted antenna which is made to be smaller, while securing strength in the base body, and where frequency is adjusted. <P>SOLUTION: The antenna comprises a plurality of side surface conductors 2 formed on the side surface of a board 1; a plurality of through-conductors 3 formed, in response to the side surface conductors 2; upper lower surface conductors 4 and lower surface conductors which connect the upper ends and lower ends of the, respectively corresponding side surface conductors 2 and through-conductors 3 so as to be a helical conductor as a whole; a wide conductor 5 connected to one end of the helical conductor; and a power feeding terminal 6 connected to the other end of the helical conductor. Consequently, the strength of the base body 1 is enhanced, and the strength is raised in spite of a small/thin antenna; and the antenna is miniaturized, while obtaining superior radiation characteristic and is made inexpensive by using a low-cost single-layer board. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a small surface-mount antenna, and more particularly to an antenna typically used for Bluetooth (registered trademark) and cellular phone diversity. The present invention also relates to a wireless communication apparatus using the antenna of the present invention.

  In response to the recent trend toward miniaturization and higher functionality of wireless communication devices, small surface-mount antennas have been used as the antennas. An example of such a conventional surface mount antenna is shown in a perspective view of FIG. According to the antenna shown in FIG. 7, a frequency in which a spiral radiation electrode 32 is formed inside a rectangular parallelepiped base 31 made of a dielectric, and one end of the spiral radiation electrode 32 is connected to the surface of the base 31. A trimming electrode 33 having a substantially rectangular shape for adjustment is provided. Reference numeral 34 denotes a power feeding terminal which is formed on the surface of the base 31 and to which the other end of the spiral radiation electrode 32 is connected. According to this, by forming the radiation electrode 32 in a spiral shape, the radiation electrode 32 can be accommodated in a small space, and the antenna can be miniaturized. Further, by appropriately trimming the trimming electrode 33, it is possible to correct the deviation of the resonant frequency of the antenna caused by the manufacturing dimensional variation of the spiral radiating electrode 32 and the dielectric constant variation of the dielectric of the substrate 31. It can be done.

FIG. 8 is a perspective view showing an example of a small chip antenna as another example of a small surface mount antenna. In the antenna shown in FIG. 8, the pattern of the radiation electrode 42 is formed on the dielectric substrate 41 by providing a folded portion 42 a that is folded at least once so as to be substantially parallel along the longitudinal direction. The power supply portion 43 is provided on the one end portion 42b side, and the other end portion 42c side is formed wider than the one end portion 42b side. Thereby, a top-loading type small chip antenna is supposed to be formed. The electric length is ensured by folding the radiation electrode 42 and formed between the wide end 42c and the grounding conductor of the circuit board. Since the capacity to be increased can be increased, the resonance frequency of the antenna can be lowered, that is, the antenna can be reduced in size.
Japanese Patent Laid-Open No. 10-247808 Japanese Patent No. 3253255

  However, although the antenna shown in FIG. 7 is small, there is a problem that the strength is lowered because the base 31 is elongated. Further, since the trimming electrode 33 formed on the surface of the base 31 is provided on one end of the spiral radiating electrode 32 formed inside the base 31, the spiral radiating electrode 32 is formed inside the base 31 by a lamination process. There is also a problem that manufacturing is difficult and expensive due to the necessity of forming and a manufacturing process of a multilayer structure. Furthermore, since the frequency of this antenna also varies depending on the matching circuit mounted on the circuit board on which the antenna is mounted, it is necessary to adjust the trimming electrode 33 after the antenna and the matching circuit are attached to the circuit board. There is a problem that the frequency cannot be matched. In this case, adjusting after attaching to the circuit board has a problem that it is difficult to remove metal powder or the like generated by trimming. In particular, since a small antenna generally has a narrow band, this problem of frequency adjustment is a serious problem.

  In the other small chip antenna shown in FIG. 8, the radiation electrode 42 by one turn-back has a longer radiation electrode 42. Therefore, the antenna can be downsized compared to the case of using a spiral radiation electrode. There is a problem that it is difficult to plan.

  The present invention has been devised in view of the problems in the prior art as described above, and the purpose thereof is a surface that can be downsized while ensuring the strength of the substrate and can also be adjusted in frequency. It is to provide a mountable antenna.

  The antenna of the present invention includes a plurality of side conductors formed on the side surface of the substrate from the upper surface to the lower surface, and a plurality of through conductors formed through the upper and lower surfaces of the substrate and corresponding to the side conductors, respectively. An upper surface conductor and a lower surface conductor formed on the upper surface and the lower surface of the substrate, the upper and lower conductors connecting the corresponding side conductors and the through conductors so as to form a spiral conductor as a whole, and the substrate A wider conductor connected to one end of the spiral conductor, and formed on a surface of the substrate, which is wider than the upper conductor along the side surface of the portion different from the portion where the side conductor is formed on the upper surface of the substrate. And a power supply terminal connected to the other end of the spiral conductor.

  In the antenna of the present invention, in the above configuration, the side surface of the portion of the substrate on which the side conductor is formed is linear, and the arrangement of the plurality of through conductors is not parallel to the side surface as a whole. It is a feature.

  The antenna of the present invention is characterized in that, in the above configuration, a matching circuit having an inductance and a capacitance is provided between the feeding terminal and the other end of the spiral conductor.

  The wireless communication device of the present invention includes any one of the above-described antennas of the present invention and a circuit board on which the antenna is mounted and a grounding conductor is formed except in the vicinity of the mounting portion. It is a feature.

  According to the antenna of the present invention, a plurality of side conductors formed on the side surface of the substrate from the upper surface to the lower surface, and a plurality of penetrations formed through the upper and lower surfaces of the substrate and corresponding to the side conductors, respectively. An upper surface conductor and a lower surface conductor that connect the upper ends and the lower ends of the conductor and the corresponding side conductors and the through conductors formed on the upper surface and the lower surface of the substrate so as to form a spiral conductor as a whole, A wide conductor formed wider than the top conductor along a side surface of a portion different from the portion where the side conductor is formed on the top surface of the substrate, and connected to one end of the spiral conductor, and the surface of the substrate And the radiation electrode is composed of a spiral conductor and a wide conductor, and the substrate has a substrate other than the portion of the spiral conductor. Hiro The strength of the substrate for which it is possible to sufficiently secure, you are possible to increase the strength while being small and thin antenna. In addition, by forming the wide conductor so that it is positioned beside the spiral conductor on the upper surface of the base, the capacitance is efficiently provided between the wide conductor and the grounding conductor of the circuit board when the antenna is mounted on the circuit board. Thus, the antenna can be miniaturized while obtaining good radiation characteristics, and an inexpensive antenna can be obtained by using a low-cost single-layer substrate.

  In addition, since the wide conductor connected to one end of the spiral conductor is formed on the upper surface of the base, the grounding conductor is provided between the spiral conductor capable of increasing the electrical length and the grounding conductor of the circuit board. By providing a wide conductor that can form a large capacitance with the conductor, it is possible to efficiently reduce the size of the antenna while realizing good radiation characteristics, and trim the wide conductor after mounting on the circuit board. Thus, adjustment to a desired frequency characteristic can be easily performed.

  According to the antenna of the present invention, when the side surface of the portion of the substrate on which the side conductor is formed is straight, and the arrangement of the plurality of through conductors is not parallel to the side as a whole, the through conductor Since the arrangement of the through holes for forming the antenna is dispersed, the stress generated with respect to the bending load is dispersed, so that the mechanical strength of the antenna can be improved.

  According to the antenna of the present invention, when a matching circuit having an inductance and a capacitance is provided between the feeding terminal and the other end of the spiral conductor, the matching is performed on a circuit board on which the antenna is mounted. Since a circuit is not required, for example, by trimming a wide conductor by measurement on an evaluation board, it is possible to correct a frequency shift due to variations in component constants of a matching circuit mounted on an antenna. An antenna with a small frequency shift due to variations in the component constants of the matching circuit can be obtained.

  According to the wireless communication apparatus of the present invention, the antenna of the present invention and the circuit board on which the antenna is mounted and the grounding conductor is formed except for the vicinity of the mounting portion are provided. Since the bandwidth of the antenna with high frequency accuracy can be widened, a small wireless communication device can be realized with a small and high performance antenna.

  Hereinafter, an antenna of the present invention and a wireless communication apparatus using the antenna will be described in detail with reference to the drawings.

  FIG. 1 is a top view showing an example of an embodiment of the antenna of the present invention. In FIG. 1, reference numeral 1 denotes an antenna substrate, 2 denotes a plurality of side conductors formed on the side surface of the substrate 1 from the upper surface to the lower surface, and 3 denotes a plurality of side conductors penetrating through the upper and lower surfaces of the substrate 1. The formed through conductors 4 are upper surface conductors formed on the upper surface of the substrate 1 and connecting upper ends of the corresponding side conductors 2 and the through conductors 3 respectively. Similarly to the upper surface conductor 4, the lower surface of the corresponding side conductor 2 and the through conductor 3 are connected to the lower surface of the substrate 1 to form a spiral shape together with the side conductor 2, the through conductor 3 and the upper surface conductor 4. A bottom conductor that forms the conductor is formed. Reference numeral 5 denotes a wide conductor formed wider than the upper surface conductor 4 along the side surface of a portion different from the portion where the side conductor 2 is formed on the upper surface of the substrate 1 and connected to one end of the spiral conductor. Is a power supply terminal formed on the surface of the substrate 1, in this example from the upper surface to the side surface, and connected to the other end of the spiral conductor.

  As shown in FIG. 1, the antenna of the present invention has a plurality of side conductors 2 formed on the side surface of the substrate 1 from the upper surface to the lower surface, and the upper and lower surfaces of the substrate 1 respectively corresponding to the side conductors 2. The plurality of formed through conductors 3 and the upper and lower ends of the corresponding side conductors 2 and through conductors 3 formed on the upper and lower surfaces of the substrate 1 are connected so as to form a spiral conductor as a whole. The upper and lower conductors 4 and 4 are formed so as to be wider than the upper conductor 4 along the side of a portion different from the portion where the side conductor 2 is formed on the upper surface of the substrate 1 and connected to one end of the spiral conductor. A wide conductor 5 and a feed terminal 6 formed on the surface of the substrate 1 and connected to the other end of the spiral conductor. Accordingly, a long radiation electrode can be formed by effectively using the upper and lower surfaces of the antenna, and a sufficiently large capacitance component formed between the wide conductor 4 and the grounding conductor of the circuit board. A small antenna having a low resonance frequency can be obtained.

  Next, FIG. 2 is a top view similar to FIG. 1, showing another example of the embodiment of the antenna of the present invention. In FIG. 2, the same reference numerals are given to the same parts as in FIG. 1, 1 is a substrate, 2 is a side conductor, 3 is a through conductor, 4 is a top conductor, 5 is a wide conductor, and 6 is a power supply terminal.

  In the example shown in FIG. 2, the side surface of the portion of the substrate 1 where the side conductors 2 are formed is linear, and the plurality of through conductors 3 are arranged alternately and far from each other. Are arranged so as to constitute a two-row arrangement, and are formed so as not to be parallel to the side surfaces as a whole. Thus, when the arrangement of the plurality of through conductors 3 is not parallel to the side surface on which the side conductors 2 are formed as a whole, the arrangement of the through holes for forming the through conductors 3 is dispersed, so that the bending load is reduced. On the other hand, since the generated stress is dispersed, the mechanical strength of the antenna can be improved.

  In addition, as an arrangement in which the arrangement of the plurality of through conductors 3 is not parallel to the side surface of the substrate 1 as a whole, in addition to arranging the through conductors 3 alternately in two rows as in the example shown in FIG. It may be a three-row arrangement, or may be a curve or waveform arrangement.

  Next, FIG. 3 is a top view similar to FIGS. 1 and 2, showing still another example of the antenna according to the present invention. Also in FIG. 3, the same reference numerals are given to the same parts as in FIG. 1, 1 is a substrate, 2 is a side conductor, 3 is a through conductor, 4 is a top conductor, 5 is a wide conductor, and 6 is a feed terminal. . Reference numeral 7 denotes a matching circuit provided between the feeding terminal 6 and the other end of the spiral conductor and having inductance and capacitance. Reference numeral 9 denotes the matching circuit 7 which is grounded to a circuit board on which the antenna is mounted. This is a ground terminal for connection to the conductor.

  In the example shown in FIG. 3, a matching circuit 7 having an inductance and a capacitance is provided between the feeding terminal 6 and the other end of the spiral conductor, so that the input impedance of the antenna is matched by the matching circuit 7. In addition, the frequency deviation caused by the variation in the constants of the chip components used in the matching circuit 7 or the variation in the dimensions of the reactance formed by the pattern is corrected by trimming the wide conductor 5, thereby realizing an antenna with high frequency accuracy. Will be able to.

  As the matching circuit 7 having such an inductance and a capacitance, a reactance element such as an inductor or a capacitor using a normal chip component may be used. Moreover, this may be used as a reactance element by forming an inductor or a capacitor with a conductor pattern on the substrate 1. In particular, when the matching circuit 7 is composed of chip parts, a small matching circuit 7 can be obtained.

  In the antenna of the present invention as described above, the substrate 1 has a rectangular parallelepiped shape made of a dielectric or magnetic material. Further, it may be a disc shape, a semi-disc shape, a rectangular shape with rounded corners, or the like. In particular, when the shape of the substrate 1 is a rectangular shape with rounded corners, the rounded corners are matched to the rounded corners of the casing of the wireless communication device, so that the space of the wireless communication device can be used more effectively. Will be able to.

  The substrate 1 is manufactured using, for example, ceramics obtained by pressure-molding and firing a powder made of a dielectric material (relative dielectric constant εr: 9.6) mainly composed of alumina. Further, the substrate 1 may be a composite material of ceramic and resin as a dielectric, or a magnetic material such as ferrite.

When the substrate 1 is made of a dielectric, the propagation speed of the high-frequency signal propagating through the radiation electrode composed of the spiral conductor composed of the side conductor 2, the through conductor 3, the upper conductor 4 and the lower conductor and the wide conductor 5 is low. become shorter wavelengths occur, the effective length of the conductor pattern of the radiation electrode and the dielectric constant of the substrate 1 and epsilon _r becomes epsilon _r ^1/2 times, the effective length increases. Therefore, if the same characteristics as the conventional antenna characteristics are used, the pattern length of the conductor pattern of the radiation electrode can be set to 1 / (ε _r ^1/2 ), and the antenna can be miniaturized.

When the substrate 1 is made of a dielectric, if ε _r is lower than 3, it is difficult to meet the market demand for antenna miniaturization by approaching the relative dielectric constant (ε _r = 1) in the atmosphere. Tend to be. Furthermore, epsilon when _r is greater than 20, although miniaturization possible, since the gain and bandwidth of the antenna is proportional to antenna size, antenna gain and bandwidth is too small, not fulfill the characteristics as antenna trend There is. Therefore, when the substrate 1 is made of a dielectric, it is desirable to use a dielectric material having a relative dielectric constant ε _r of 3 to 20, more preferably 10 or less. Examples of such dielectric materials include ceramic materials such as alumina ceramics and zirconia ceramics, and resin materials such as tetrafluoroethylene and glass epoxy.

  On the other hand, when the substrate 1 is made of a magnetic material, the impedance of the radiation electrode is increased, so that the antenna Q can be lowered and the bandwidth can be increased.

When fabricating a substrate 1 of a magnetic material, when the relative permeability mu _r exceeds 8, though the bandwidth of the antenna is wider, since the gain and bandwidth of the antenna is proportional to antenna size, antenna gain and bandwidth There is a tendency that the width becomes too small and the characteristics as an antenna are not achieved. Therefore, when manufacturing a substrate 1 of a magnetic material, it is desirable that the relative permeability mu _r is used 1 to 8 of the magnetic material. Examples of such a magnetic material include YIG (yttria, iron, garnet), Ni-Zr compounds, Ni-Co-Fe compounds, and the like.

  For example, aluminum, copper, nickel, silver, palladium, side conductor 2, penetrating conductor 3, spiral conductor consisting of upper surface conductor 4 and lower surface conductor, and wide conductor 5, as well as feed terminal 6 and ground terminal 9, It is made of a metal whose main component is either platinum or gold. In order to form the pattern of each conductor with these metals, various printing methods, thin film formation methods such as vapor deposition methods, sputtering methods, metal foil laminating methods, plating methods, etc., respectively, are desired. A pattern-shaped conductor layer, a so-called through-hole conductor, a via-hole conductor, a conductor obtained by halving them, or the like may be formed inside a predetermined upper surface, lower surface, side surface, or upper and lower surfaces of the substrate 1.

  In the antenna of the present invention, the number of turns can be increased as the helical radiating conductor is made thinner. In consideration of the conductor resistance, it is desirable that the conductor has a width of 0.3 mm or more and a thickness of 0.01 mm or more.

  Further, the wider the wider conductor 5 is, the larger the capacitance between the wide conductor 5 and the grounding conductor 11 is. However, when the width is increased, there arises a problem that a cutting margin when trimming is increased. When used in a wireless communication device such as a mobile phone, the width of the wide conductor 5 is preferably 6 mm or less.

  In addition, the ground terminal 9 when the power supply terminal 6 and the matching circuit 7 are provided preferably has a conductor width of 0.3 mm or more and a thickness of 0.01 mm or more in consideration of conductor resistance.

  Next, an example of an embodiment of a circuit board on which the antenna of the present invention is mounted, which is used in the wireless communication apparatus of the present invention, is shown in a top view in FIG. In FIG. 4, 1 is an antenna substrate, 2 is a side conductor, 3 is a through conductor, 4 is an upper conductor, 5 is a wide conductor, and 6 is a feed terminal. Further, 10 is a circuit board, 11 is a grounding conductor formed on the upper surface of the circuit board 10 except for the vicinity of the antenna mounting portion, and 12 is formed on the upper surface of the circuit board 10 and is connected to the feeding terminal 6. It is the electrode for electric power feeding connected.

  As shown in FIG. 4, in the circuit board 10 on which the antenna of the present invention is mounted, which is used in the wireless communication apparatus of the present invention, the grounding conductor 11 formed on the upper surface that is the mounting surface of the antenna is the antenna. It is necessary to form it except the vicinity of the mounting part. The reason for this is that when the grounding conductor 11 is not removed, the image resistance of the current flowing through the radiation electrode of the antenna flows through the grounding conductor 11 to significantly reduce the radiation resistance, and the antenna characteristics are very narrow. This is because it becomes a band and the radiation efficiency is low.

  As shown in FIG. 4, the antenna of the present invention needs to be mounted on the mounting portion of the circuit board 10 excluding the grounding conductor 11. Since the spiral conductor of the antenna of the present invention is a portion where current flows strongly in resonance generated by the spiral conductor and the wide conductor 5, the circuit board 10 is designed to reduce the image current flowing through the grounding conductor 11. Desirably, the grounding conductor 11 is arranged so as to be as far as possible from the opposite edge of the grounding conductor 11. Accordingly, the wide conductor 5 may be disposed between the edge of the grounding conductor 11 and the spiral conductor in order to reduce the current and ensure a sufficient capacity formed between the grounding conductor 11. desirable. By doing so, it is possible to minimize the deterioration of the antenna characteristics due to the image current flowing through the grounding conductor 11, and to make the antenna with a small loss.

  In the antenna of the present invention mounted on the circuit board 10 with a predetermined relationship with the grounding conductor 11 as described above, it is preferable that a desired capacitance is formed between the grounding conductor 11 and the wide conductor 5. In order to exhibit excellent radiation characteristics, the shape of the substrate 1 is a rectangular parallelepiped, the wide conductor 5 is located near the grounding conductor 11, the side conductor 2, the through conductor 3, the upper conductor 4, and the lower conductor It is desirable that the helical conductor made of a conductor is located on the end portion side of the substrate 1 at a site away from the grounding conductor 11. This is because when the distance between the spiral conductor and the grounding conductor 11 is short, a current that cancels the current flowing through the spiral conductor flows through the grounding conductor 11, and the conductor resistance causes a decrease in antenna gain. Because it will be. Therefore, it is desirable that the spiral conductor be provided at the end portion on the side surface side that is far from the grounding conductor 11 of the substrate 1 so as to be mounted as far as possible from the grounding conductor 11 of the circuit board 10.

  As such a circuit board 10, a normal circuit board such as glass epoxy or alumina ceramic is used.

  The ground conductor layer 11 is formed of a conductor used for a normal circuit board such as copper or silver.

  For mounting the antenna of the present invention on the upper surface of the circuit board 10 and connecting the feeding terminal 6 to the feeding electrode 12, solder mounting using a reflow furnace or the like can be used.

  As a method for manufacturing the antenna of the present invention, the side conductor 2 is formed on the side surface of the substrate 1 from the upper surface to the lower surface, and the through conductor 3 is formed so as to penetrate the upper and lower surfaces corresponding to the side conductor 2. Cost through-hole printing can be applied. By applying the through-hole printing method, a substrate region to be a substrate 1 of a plurality of antennas is formed on a large-area mother substrate by arranging an array of through-hole conductors to be side conductors 2 after division, By dividing the mother board at the position where the through-hole conductors are arranged, the board is divided into individual boards 1 to obtain a large number of antennas. After the division, the arrangement of the divided through-hole conductors becomes a plurality of side conductors 2 formed on the side surface of the substrate 1 as it is from the upper surface to the lower surface.

  At this time, when the through conductors 3 are arranged in a straight line on the antenna substrate 1 so as to be parallel to the side surface on which the side conductors 2 are formed, the through hole conductors to be the through conductors 3 are arranged. Although the substrate 1 may be broken, by arranging the through conductors 3 so that the arrangement of the through conductors 3 as a whole is not parallel to the side surface of the portion where the side conductors 2 are formed as shown in FIG. 1 can be ensured, and the occurrence of cracks in the substrate 1 from locations other than the desired position can be prevented.

  In a small surface-mounted chip antenna such as the antenna of the present invention, the radiation frequency shift is caused by the current flowing through the grounding conductor of the circuit board on which the antenna is mounted rather than the dimensional accuracy of the antenna element (radiating electrode). It is well known that it contributes greatly. When the distance between the grounding conductor formed by removing the antenna and the antenna on the circuit board on which the small surface-mount antenna is mounted becomes narrow, the band of the antenna sharply narrows and the radiation efficiency also decreases. . For example, regarding a 900 MHz band application for a mobile phone, a surface-mounted chip antenna using a 10 mm × 2 mm × 2 mm substrate needs to be mounted about 7 mm away from a grounding conductor. At this time, the bandwidth is about 20 MHz, and if the accuracy of the resonance frequency of the antenna is high, it can be used, for example, for reception diversity of Japanese PDC (Personal Digital Cellular).

  On the other hand, in the antenna of the present invention, the distance between the grounding conductor 11 and the helical conductor functioning as a helical antenna is maximized in the size of the substrate 1 of the antenna, Utilizing the space to improve the strength of the antenna, and at the same time reduce the manufacturing cost by using the substrate 1 that can be manufactured at low cost, and further includes the matching circuit 7 and the wide conductor 5 for frequency adjustment. Thus, the resonance frequency accuracy of the antenna is improved.

  The antenna of the present invention is a spiral conductor formed of a side conductor 2, a through conductor 3, an upper conductor 4, and a lower conductor, as shown in a top view in FIG. May be formed over two side surfaces of the rectangular parallelepiped substrate 1. According to the example having the spiral conductor configured as described above, the length of the spiral conductor, which is the radiation electrode, is increased, so that the antenna having the same frequency characteristic is placed on one side surface of the substrate 1. Thus, the antenna can be further reduced in size as compared with the one formed.

  Using the rectangular parallelepiped substrate 1 made of alumina ceramics having a length of 9 mm, a width of 5 mm, and a thickness of 1 mm, the antenna of the present invention having a configuration as shown in a perspective view in FIG. 5 is manufactured, and the resonance frequency is measured. Was done.

  In the antenna shown in FIG. 5, 1 is a substrate, 2 is a side conductor, 3 is a through conductor, 4 is a top conductor, 5 is a wide conductor, 6 is a power supply terminal, and 9 is a ground terminal. Reference numerals 13, 14, and 15 denote chip inductors as inductances constituting the matching circuit 7. Reference numeral 20 denotes a trimming line for the wide conductor 5. The trimming line 20 was set such that the width of the wide conductor 5 was 2 mm in width and 5 mm in length, and 1 mm from the tip.

  An FR-4 single-sided copper-clad substrate having a width of 40 mm, a length of 80 mm, and a thickness of 0.8 mm was used for the circuit board 10 on which the antenna of the present invention was mounted. In this circuit board 10, the grounding conductor 11 was removed over a range of 10 mm in length and 6 mm in width, and an antenna was mounted on that portion as shown in FIG.

For such an antenna of the present invention, the frequency before and after the wide conductor 5 was cut by the trimming line 20 was measured, and the frequency change due to the trimming was examined. The results are shown in Table 1.

  From the results shown in Table 1, it can be seen that the frequency can be adjusted by the matching circuit 7 provided in the antenna. It can also be seen that even when the antenna radiation frequency is shifted due to variations in impedance adjustment by the matching circuit 7, the frequency can be corrected to a desired value by trimming the wide conductor 5.

  The antenna of this embodiment has a substrate 1 having a length of 9 mm and is very small, one-third of the wavelength of the radiation frequency (about 1 GHz). Therefore, when the VSWR (Voltage Standing Wave Ratio) is 3, the bandwidth is as narrow as 30 MHz. In order to put an antenna having such a narrow band into practical use, it is required that the resonance frequency is highly accurate. However, surface mount chip antennas usually have low yields due to variations in antenna frequency due to dimensional accuracy of the radiation electrode conductors formed on the antenna and variations in the characteristics of the components used in the matching circuit. Yes. On the other hand, according to the antenna of the present invention, the frequency shift caused by the dimensional accuracy of the spiral conductor and the variation in the parts used in the matching circuit 7 is adjusted to a desired frequency by trimming the wide conductor 5. It was confirmed that this can be avoided.

It is a top view which shows an example of embodiment of the antenna of this invention. It is a top view which shows the other example of embodiment of the antenna of this invention. It is a top view which shows the further another example of embodiment of the antenna of this invention. It is a top view which shows the example of embodiment of the circuit board mounted with the antenna of this invention used for the radio | wireless communication apparatus of this invention. It is a perspective view which shows the Example of the antenna of this invention. It is a perspective view which shows the other example of embodiment of the antenna of this invention. It is the perspective view which saw through the inside which shows the example of the antenna of a prior art. It is a perspective view which shows the example of the antenna of a prior art.

Explanation of symbols

1: Substrate 2: Side conductor 3: Through conductor 4: Top conductor 5: Wide conductor 6: Feed terminal 7: Matching circuit 9: Ground terminal
10: Circuit board
11: Circuit board ground conductor
12: Final power electrode
13, 14, 15: Chip inductors that are parts of matching circuits
20: Wide conductor trimming line

Claims (4)

A plurality of side conductors formed on the side surface of the substrate from the upper surface to the lower surface; a plurality of through conductors formed through the upper and lower surfaces of the substrate so as to correspond to the side conductors; An upper surface conductor and a lower surface conductor, which are formed on the lower surface, are connected so that the upper ends and lower ends of the corresponding side conductors and the through conductors as a whole become a spiral conductor, and the side conductors on the upper surface of the substrate Formed on the surface of the substrate, the wide conductor connected to one end of the spiral conductor, and wider than the top conductor along the side surface of the portion different from the portion where the spiral is formed. An antenna comprising: a power supply terminal connected to the other end of the conductor. The antenna according to claim 1, wherein the side surface of the portion of the substrate on which the side conductor is formed is linear, and the plurality of through conductors are not arranged in parallel to the side surface as a whole. 2. The antenna according to claim 1, wherein a matching circuit having an inductance and a capacitance is provided between the feeding terminal and the other end of the spiral conductor. A radio comprising: the antenna according to any one of claims 1 to 3; and a circuit board on which the antenna is mounted and a grounding conductor is formed except in the vicinity of the mounting portion. Communication device.

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