JP3810075B2 - Portable wireless communication device - Google Patents

Description

  The present invention relates to a portable wireless communication apparatus that can suppress a decrease in antenna radiation efficiency during a call.

  In conventional portable wireless communication devices, in addition to the original antenna, a high-frequency current also flows from the feeding point of the antenna to the ground plane constituted by the ground pattern of the housing and the built-in substrate, and these act as another pseudo antenna. There is a phenomenon that. If a high-frequency current flows over a wide area of the ground plane, the antenna shape may change equivalently, leading to a decrease in radiation efficiency. Therefore, a notch (slit) is provided in a part of the housing or substrate to An invention has been made to suppress the spread and prevent a decrease in radiation efficiency (see, for example, Patent Document 1 or Patent Document 2).

  On the other hand, there is also known a technique for suppressing the high-frequency current flowing through the ground plane by attaching the high-frequency current control element to the ground plane, but the frequency at which the effect is exhibited varies depending on the size and mounting position of the high-frequency current control element. There has also been an invention in which a plurality of high-frequency current control elements are used in combination to broaden the bandwidth (see, for example, Patent Document 3).

However, these conventional techniques also provide a phenomenon in which the electromagnetic field strength increases locally and intensively due to current concentration in the vicinity of the feeding point, or on the side closer to the user when the portable wireless communication device is used during a call. However, the high-frequency current flowing through the high-frequency current control element has a problem that the radiation efficiency is lowered.
JP-A-5-327527 (2nd to 4th pages, FIG. 1) JP 2001-274719 A (2nd to 4th pages, FIG. 1) JP 2001-308622 A (2nd to 4th pages, FIG. 1)

  In a conventional portable wireless communication device, the higher the frequency current control element is added to the position closer to the feeding point on the ground plane, the higher the frequency current can be prevented from flowing to the other part of the ground plane. Thus, there is a problem that current concentration occurs near the feeding point. On the other hand, there is a problem that, as the position where the high-frequency current control element is added is further away from the feeding point, the high-frequency current diffuses on the ground plate and the original function of the high-frequency current control element cannot be exhibited.

  The present invention has been made to solve the above-described problem, and is a portable radio capable of preventing a decrease in antenna radiation efficiency by exhibiting the original function of a high-frequency current control element while suppressing current concentration in the vicinity of a feeding point. An object is to provide a communication device.

In order to achieve the above object, an antenna device according to the present invention includes a ground pattern, a gap portion formed by cutting a part of a peripheral portion of the ground pattern, and the ground pattern adjacent to the gap portion. A board having an antenna mounting portion formed in a jetty shape, an antenna element fed from a feeding point provided near the tip of the antenna mounting portion , and the feeding point near the root of the antenna mounting portion A high frequency current control element coupled to the ground pattern is provided at a current control point provided at a distance of a quarter wavelength or less.

  According to the present invention, the high-frequency current flowing from the feeding point to the ground plane is confined in the antenna mounting portion in which the ground pattern is formed in a jetty shape, and a distance of a quarter wavelength or less from the feeding point is provided inside the portion. Since it is absorbed by the high-frequency current control element from the current control points provided at a distance, it is possible to achieve both suppression of current concentration and display of the original function of the high-frequency current control element.

  Embodiments of the present invention will be described below with reference to the drawings.

  Hereinafter, Embodiment 1 of the present invention will be described with reference to FIGS. 1 and 2. FIGS. 1A and 1B are diagrams showing the configuration of the portable wireless communication apparatus according to the first embodiment of the present invention only in a portion directly related to the present invention, and FIG. FIG. 4B is a perspective view.

  In the figure, a substrate 1 is a substrate provided with a grounding pattern and acting as a ground plane. The gap portion 2 is a gap formed by cutting a part of the peripheral edge of the substrate 1. The jetty-shaped portion 3 is a grounding pattern formed by cutting out the gap portion 2 from the substrate 1. The facing portion 4 is a grounding pattern that faces the jetty-shaped portion 3 across the gap portion 2. The high-frequency current control element 5 is coupled to the ground pattern of the jetty-shaped portion 3 and is formed in an L shape. The current control point 6 is a point where the ground pattern of the jetty-shaped portion 3 and the high-frequency current control element 5 are connected.

  In this shape, the right edge of the upper peripheral edge of the substrate 1 having the ground pattern is cut in the vertical direction to form a gap portion 2, and the peripheral edge adjacent to the gap 2 (in this case, the right peripheral edge). The ground contact pattern formed between them becomes the jetty-shaped portion 3. The jetty-shaped portion 3 serves as a mounting portion for the antenna element 7.

  Next, the antenna element 7 is an antenna connected to the feeding point 8 of the jetty-shaped portion 3 of the substrate 1 and formed from a rod-shaped conductor. The current control point 6 and the feeding point 8 are both formed inside the jetty-shaped portion 3 and the distance between them is a quarter wavelength (λ / 4) or less. The longitudinal size of the high-frequency current control element 5 is about a quarter wavelength. The high-frequency current control element 5 may be directly connected to the ground pattern of the jetty portion 3 at the current control point 6, or may be electrostatically coupled to the ground pattern of the jetty portion 3 with a dielectric interposed therebetween. (This is called “join” in both cases.) Further, the high-frequency current control element 5 may be attached to either the front or back surface of the jetty-shaped portion 3, or may be attached from the current control point 6 in the vertical direction.

  Further, the gap portion 3 may be formed by cutting away a part of the ground pattern of the peripheral portion instead of a portion of the peripheral portion of the substrate 1. Alternatively, the gap may be formed by cutting a part of the peripheral portion including the grounding pattern of the substrate 1 and filling a medium having a dielectric constant different from that of the base material of the substrate 1. Note that other configurations of the portable wireless communication device are not directly related to the present invention, and thus are not shown in the figure.

  Here, the shape of the high-frequency current control element 5 is not necessarily limited to the L shape as shown in FIG. Further, the antenna element 7 is not necessarily limited to the rod-shaped conductor as shown in FIG. 1, and for example, a helical antenna, an inverted F antenna, a dielectric antenna, or the like may be used.

  In this configuration, the high-frequency current flowing through the jetty portion 3 of the substrate 1 is fed from the feeding point 8 to the antenna element 7, but part of the high-frequency current also flows inside the jetty portion 3 that is the ground pattern. A non-zero finite value is taken at the current control point 6 at a distance equal to or less than a quarter wavelength from. The high-frequency current has a minimum current value at a distance of a quarter wavelength from the feeding point 8, and becomes a non-phase current having a non-zero finite value when it exceeds a quarter wavelength. Therefore, the effect of suppressing the current below the substrate 1 described below is not lost at all even when the distance between the current control point 6 and the feeding point 8 is a quarter wavelength or more. The supply efficiency decreases as it decreases in inverse proportion to the square of the distance.

  If the size of the high-frequency current control element 5 in the longitudinal direction is about a quarter wavelength, the input impedance at the current control point 6 is minimized, so that most of the high-frequency current flowing through the jetty-shaped portion 3 is high-frequency. The high frequency current that is absorbed by the current control element 5 and flows below the substrate 1 can be made extremely small.

  Here, as the distance between the current control point 6 and the feeding point 8 of the jetty-shaped portion 3 is reduced, the current flowing below the substrate 1 can be reduced. However, the high-frequency current is concentrated in the vicinity of the feeding point 8. The electromagnetic field strength is locally increased. Then, depending on the surrounding conditions, such as when the user's head is close like during a call, the radiation efficiency may be reduced. Therefore, it is necessary to appropriately set the interval between the current control point 6 and the feeding point 8 while observing the change in radiation efficiency in the use state. Can be set. In addition, as long as the requirements regarding the distance between the current control point 6 and the feeding point 8 are satisfied, the size of the jetty-shaped portion 3 may be any number.

  The effect of attaching the high-frequency current control element 5 in FIG. 1A can be explained as the occurrence of two resonances as follows. The first resonance is caused by a current path from the antenna element 7 through the jetty-shaped portion 3 to the high-frequency current control element 5. The second resonance is caused by a current path from the antenna element 7 through the jetty-shaped portion 3 to the substrate 1 (however, a high-frequency current flows through the ground plane, resulting in a decrease in radiation efficiency. That is, the resonance associated with the second resonance). The point is premised on the frequency at which such a decrease is allowed.) The gap portion 2 contributes to this, and two resonances in which the first resonance and the second resonance are clearly separated can be realized.

  FIG. 2 shows an example of a result of evaluating the effect of the present invention by simulation from the viewpoint of the radiation efficiency of the antenna. FIG. 2 (a) illustrates the simulation conditions, in which the portable wireless communication device composed of the substrate 1 and the antenna element 7 is placed at a distance of 5 mm from the dielectric lossy medium. In this case, the size of the dielectric lossy medium is, for example, 200 mm × 200 mm × 200 mm. This simulates a state in which the portable wireless communication device is close to the user's head during a call.

  FIG. 5B shows the result of the antenna radiation efficiency obtained by simulation for each type of portable wireless communication device, and is a value when the radiation efficiency in free space is 100%.

  Type 1 is a type in which neither the gap portion 2 nor the high-frequency current control element 5 is provided on the substrate 1, and the radiation efficiency is 9%. On the other hand, Type 2 is a type in which only the high-frequency current control element 5 is provided on the substrate 1, and the radiation efficiency is 14%. Type 3 is a type in which only the gap portion 2 is provided on the substrate 1 and the jetty-shaped portion 3 is formed, and the radiation efficiency is 9%. Type 4 is a type (Example 1) in which a high-frequency current control element 5 is provided on a jetty-shaped portion 3 formed by providing a gap portion 2 on a substrate 1. It can be seen that the radiation efficiency of Type 4 is 18 percent, which is higher than that of Types 1 to 3, and twice that of Type 1 or Type 3.

  According to the first embodiment of the present invention, by providing both the gap portion 2 and the high-frequency current control element 5 on the substrate 1, it is possible to suppress a decrease in antenna radiation efficiency.

  Next, Embodiment 2 of the present invention will be described with reference to FIG. FIG. 3 shows, as a front view, a configuration including the substrate 1, the antenna element 7, and the high-frequency current control element 5, as in FIG. . Reference numerals 1 to 8 in the figure are all the same as those in FIG. 1A, and their explanation is omitted. However, the opposing portion 4 of the substrate 1 is formed in a concavo-convex shape in FIG. ) Is different.

  When the width of the gap portion 2 is narrowed so that the effective area of the substrate 1 is not reduced, a high-frequency current opposite to the high-frequency current flowing in the jetty-shaped portion 3 is induced in the facing portion 4 of the substrate 1. Cause unnecessary electromagnetic field radiation. Therefore, in the second embodiment, as shown in FIG. 3, the shape of the facing portion 4 of the substrate 1 is made uneven so that the path of the induced current is complicated and the generation of the induced current flowing through the facing portion 4 can be suppressed. it can. As a result, an effect equivalent to increasing the width of the gap portion 2 can be obtained.

  Therefore, according to the second embodiment of the present invention, by making the shape of the facing portion 4 uneven, the width of the gap portion 2 of the substrate 1 can be made narrower than when not forming an uneven shape. There is an advantage that the area of the substrate 1 is not sacrificed.

  Next, Embodiment 3 of the present invention will be described with reference to FIG. 4 (a), 4 (b), and 4 (c) illustrate a portable wireless communication apparatus according to a third embodiment of the present invention, as in FIG. 1 (b), the substrate 1, the antenna element 7, and the high-frequency current control elements 51 and 52. Or the structure which consists of 53 is represented as a perspective view. Here, FIG. 4A shows a case where a high-frequency current control element 51 made of a spiral conductor is provided, and FIG. 4B shows a high-frequency current control element 52 made of a meander-type conductor. FIG. 4C shows a case where the high-frequency current control element 53 configured by a cubic-shaped dielectric antenna is provided. The high-frequency current control element 51 or 52 having such a shape can ensure a required electric length even in a narrow space. In addition, the high-frequency current control element 53 can ensure a required electrical length with a smaller dimension than the conductor due to the wavelength shortening effect. Therefore, Example 3 is suitable for the use of a small device such as a portable wireless communication device.

  According to the third embodiment of the present invention, the high-frequency current control element 51, 52 or 53 having a required electrical length can be mounted in a narrow space.

  Next, Embodiment 4 of the present invention will be described with reference to FIG. FIG. 5 shows, as a front view, a configuration including a substrate 1, an antenna element 7, and a high-frequency current control element 5 in the same manner as FIG. 1A, for a portable wireless communication apparatus according to Example 4 of the present invention. . 1 is different from FIG. 1A in that the gap portion 2 and the gap portion 20 are formed on both sides of the jetty-shaped portion 3. Unlike the case of FIG. 1A, in the case of a structure in which the feeding point 8 of the jetty-shaped portion 3 cannot be provided near the corner portion of the substrate 1 due to mounting restrictions or the like, the feeding point 8 is thus formed. By cutting out the substrate 1 or the ground pattern on both sides of the substrate, the same effect as the shape shown in FIG. 1A can be obtained.

  According to the fourth embodiment of the present invention, even when there is a certain restriction on the position of the feeding point 8 of the jetty-shaped portion 3, the same effect as the first embodiment can be obtained.

  Next, Embodiment 5 of the present invention will be described with reference to FIG. 6 (a) and 6 (b) are front views of a portable wireless communication apparatus according to Embodiment 5 of the present invention, which includes a substrate 1, an antenna element 7, and a high-frequency current control element 5 as in FIG. 1 (a). It is expressed as Here, the difference between FIG. 6A and FIG. 1A is that the lumped element 9 is loaded in the gap portion 2. That is, the gap portion 2 between the substrate 1 and the jetty-shaped portion 3 is connected by the lumped constant element 9. Further, the difference between FIG. 6B and FIG. 1A is that the distributed constant element 10 is loaded in the gap portion 2. That is, the gap portion 2 between the substrate 1 and the jetty-shaped portion 3 is connected by the distributed constant element 10.

  By appropriately setting the types and constants of the lumped constant element 9 or the distributed constant element 10, the impedance of the gap portion 2 has frequency selectivity, and as a result, the impedance is selectively increased at a desired frequency. Is possible.

  As an example, by loading an inductor as the lumped constant element 9 in the gap portion 2 between the substrate 1 and the jetty-shaped portion 3, stray capacitance generated between opposing conductors across the gap portion 2 and parallel resonance occur. The impedance can be high at a desired frequency. Thereby, even if the width of the gap portion 2 is narrow, a sufficient effect can be obtained.

  In addition, it is possible to obtain a sufficient effect by loading a microstrip filter as the distributed constant element 10 in the gap portion 2 between the substrate 1 and the jetty portion 3.

  According to the fifth embodiment of the present invention, the radiation efficiency of the antenna can be controlled in a frequency selective manner.

  Hereinafter, Example 6 of the present invention will be described with reference to FIG. FIG. 7 is a perspective view showing a configuration including the substrate 1, the antenna element 7, and the high-frequency current control element 5 in the same manner as FIG. 1B, for the portable wireless communication apparatus according to the sixth embodiment of the present invention. Reference numerals 1 to 5, 7 and 8 in the figure are all the same as those in FIG. 7 is different from FIG. 1B in that a second feeding point 81 that is fed at a frequency different from that of the feeding point 8 is provided at the position of the current control point 6 in FIG. . Hereinafter, the frequencies fed to the feeding point 8 and the feeding point 81 are referred to as a first frequency and a second frequency, respectively.

  Then, as described in the first embodiment, the high-frequency current control element 5 operates as a current suppressing element or a radiating element that plays an auxiliary role with respect to the antenna element 7 that is the main antenna at the first frequency. At the same time, the high-frequency current control element 5 operates as a main antenna at the second frequency. In that case, a radiation pattern is formed by the current from the high-frequency current control element 5 through the second feeding point 81 to the substrate 1.

  That is, from the first antenna system composed of the antenna element 7, the jetty portion 3, the second feeding point 81 and the high-frequency current control element 5, the high-frequency current control element 5, the second feeding point 81 and the conductor of the substrate 1. The configured second antenna system can coexist and operate at different frequencies. In addition, in the structure shown in Example 2 thru | or Example 5, a 2nd feeding point can be provided similarly and it can also be made 2 frequency.

  According to the sixth embodiment of the present invention, an additional effect that two frequencies can be obtained by feeding power to the antenna element and the high-frequency current control element at different frequencies can be obtained.

  In the first to sixth embodiments described above, the gap portion 2 has been described with reference to the drawing in which the substrate 1 is cut out in the vertical direction from the upper peripheral edge. In these drawings, it goes without saying that the same effect can be obtained even if the gap portion 2 is formed by cutting the substrate 1 laterally from the left and right peripheral edge portions.

BRIEF DESCRIPTION OF THE DRAWINGS The structure of the portable radio | wireless communication apparatus which concerns on Example 1 of this invention is represented, (a) is a front view, (b) is a perspective view. The figure which shows an example of the result of having evaluated the effect of this invention by simulation. The figure showing the structure of the portable radio | wireless communication apparatus which concerns on Example 2 of this invention. The figure showing the structure of the portable radio | wireless communication apparatus which concerns on Example 3 of this invention. The figure showing the structure of the portable radio | wireless communication apparatus which concerns on Example 4 of this invention. The structure of the portable radio | wireless communication apparatus which concerns on Example 5 of this invention is represented, (a) is the figure which loaded the lumped constant type | mold element to the gap part, (b) is the figure which loaded the distributed constant type | mold element to the gap part. The figure showing the structure of the portable radio | wireless communication apparatus which concerns on Example 6 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrates 2 and 20 Gap part 3 Jetty part of ground pattern 4 Opposite part 5 of ground pattern High frequency current control element 51 High frequency current control element 52 which consists of a helical conductor High frequency current control element 53 which consists of meander type conductors Dielectric High-frequency current control element 6 comprising an antenna Current control point 7 Antenna element 8 Feed point 81 Second feed point 9 Lumped constant type element 10 Distributed constant type element

Claims (12)

A substrate having a ground pattern, a gap portion formed by cutting off a part of a peripheral portion of the ground pattern, and an antenna mounting portion in which the ground pattern is formed in a jetty shape adjacent to the gap portion;
An antenna element fed from a feeding point provided near the tip of the antenna mounting portion;
A high-frequency current control element coupled to the ground pattern is provided at a current control point provided at a distance of a quarter wavelength or less from the feeding point in the vicinity of the base of the antenna mounting portion . A portable wireless communication device. A substrate having a ground pattern, a gap portion formed by cutting off a part of a peripheral portion of the ground pattern, and an antenna mounting portion in which the ground pattern is formed in a jetty shape adjacent to the gap portion;
An antenna element fed from a feeding point provided near the tip of the antenna mounting portion;
A high-frequency current control element coupled to the ground pattern at a current control point provided at a distance of a quarter wavelength or less from the feeding point in the vicinity of the base of the antenna mounting portion;
A portable wireless communication apparatus comprising: impedance control means disposed in the gap portion and selectively controlling impedance of the gap portion by frequency.   The portable wireless communication device according to claim 1, wherein the gap portion is formed by cutting out a part of a peripheral part of the substrate including a part of a peripheral part of the ground pattern. .   The portable radio communication apparatus according to claim 1, wherein the antenna element is connected to the feeding point or electrostatically coupled to be fed.   The portable radio communication device according to claim 1, wherein the high-frequency current control element is connected to the ground pattern at the current control point.   The portable radio communication device according to claim 1, wherein the high-frequency current control element is electrostatically coupled to the ground pattern at the current control point.   The portable wireless communication device according to claim 1, wherein the gap portion is formed by cutting away the ground pattern on the side opposite to the antenna mounting portion so as to be uneven.   The portable radio communication device according to claim 1 or 2, wherein the high-frequency current control element is formed of a conductor having an electrical length of approximately a quarter wavelength.   3. The portable radio communication apparatus according to claim 1, wherein the high-frequency current control element is configured by a dielectric or a conductor formed in an L shape, a spiral shape, or a meander shape.   The portable radio communication apparatus according to claim 1, wherein two gap portions are formed on both sides of the antenna attachment portion.   The portable wireless communication device according to claim 2, wherein the impedance control means is a lumped constant element or a distributed constant element.   The portable radio communication device according to claim 1 or 2, wherein the high-frequency current control element is fed at a frequency different from that of the antenna element at the current control point.

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