JP2012114579A - Antenna device and frequency adjustment method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small sized high-performance double resonant antenna with which each resonant frequency can be adjusted easily and independently.SOLUTION: An antenna device 100 comprises: a base 11 which is a dielectric rectangular parallelepiped body; a feeding conductor 12 formed on a first side face 11e orthogonal to a longitudinal direction of the base 11; a radiation conductor 13 which comprises a belt-like conductive pattern formed from an upper surface 11a, a second side face 11f, and through to a bottom surface 11b of the base 11 serially; and a first terminal electrode 14 formed on the bottom surface 11b of the base 11 and near the first side face 11e so as to be connected to the feeding conductor 12. The radiation conductor 13 is a belt-like conductive pattern with a folding structure, and a whole length thereof is practically the same as λ/4 (λ is a wavelength of a fundamental wave). The radiation conductor 13 includes a first folding section which is arranged facing and near the first terminal electrode 14, having a prescribed width of gap therebetween, on the bottom surface 11b of the base 11, and whose position includes an intersection point of waveforms of a second harmonic wave and a third harmonic wave.

Description

  The present invention relates to an antenna device and a frequency adjusting method thereof, and more particularly to a structure of a surface mount type multi-resonance antenna.

  In recent years, functions such as GPS (Global Positioning System), Bluetooth (registered trademark), and wireless LAN are installed in wireless mobile terminals such as mobile phones, and the multi-functionalization of communication is progressing. With the increase in functionality of such mobile phones, the need for multi-resonant antennas is increasing. In general, in a dual resonance antenna, a dual band or a multiband can be configured using a plurality of radiation conductors having different antenna lengths. For example, Patent Document 1 uses three radiation conductors to obtain three resonances. However, in such a configuration, there is a problem that not only the antenna size increases, but also the radiation conductors interfere with each other, and the radiation efficiency decreases. Therefore, an attempt has been made to realize a multi-resonance antenna using a single radiation conductor pattern.

  For example, Patent Documents 2 and 3 propose a multi-resonant antenna that realizes multiple resonances using a single strip-shaped conductor pattern. In Patent Document 2, a loop-shaped line that is a radiation path has a folded portion, one end of the loop-shaped line is connected to a feeding point, and the other end is an open end. The open end of the line is disposed opposite to the line from the feed point to the turn-back part via a dielectric, thereby forming a capacitive coupling part, and resonating at the first to third frequencies. Is configured to do.

  In Patent Document 3, meander-shaped or helical-shaped inductor patterns called resonant conductor / track structures are inserted in series, and the resonant frequency is controlled by changing the shape. However, providing an inductor pattern of these shapes increases the radiation loss and causes a decrease in radiation efficiency. Further, the frequency that can be controlled by the capacitance component and the inductor component at the tip is about two frequencies, and it is difficult to further increase the number of resonances. In order to realize three resonances, a method of increasing one line is also shown, but in this case, as in the case of Patent Document 2, the radiation efficiency is lowered and the occupied area of the antenna is increased.

JP 2010-74489 A JP 2009-111999 A JP 2002-164729 A

  However, since the double resonance antenna of Patent Document 2 has a structure in which the radiation path is folded only once, there is a problem that the size of the antenna is large and the number of resonances is small. FIG. 15 of Patent Document 2 also shows a method of increasing one line in order to increase the number of resonances. In this case, however, the radiation efficiency is lowered and the area occupied by the antenna is increased.

  Further, since the inductor pattern is used in Patent Document 3, there is a problem that the path loss increases and the radiation efficiency decreases. Further, the frequency that can be controlled by the capacitance component and the inductor component at the tip is about two frequencies, and it is difficult to further increase the number of resonances. A method of increasing one line to realize three resonances is also shown, but in this case, as in the case of Patent Document 2, the radiation efficiency is lowered and the occupied area of the antenna is increased.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a small and high-performance multi-resonant antenna that can be easily adjusted in frequency.

  In order to solve the above-described problems, an antenna device according to the present invention includes a base made of a substantially rectangular parallelepiped dielectric, a power supply conductor formed on a first side surface perpendicular to the longitudinal direction of the base, an upper surface of the base, A radiation conductor composed of a single strip-shaped conductor pattern formed continuously over the second side surface and the bottom surface facing the first side surface, and the bottom surface of the base body, which is connected to the feeding conductor. And a first terminal electrode formed closer to the first side surface, wherein the radiation conductor is a band-shaped conductor pattern having a folded structure, and the first base electrode has a gap of a predetermined width on the bottom surface of the base. It has the 1st folding | turning part arrange | positioned facing the terminal electrode adjacently, It is characterized by the above-mentioned.

  In the present invention, the total length of the radiation conductor is substantially equal to λ / 4 (λ is the wavelength of the fundamental wave), and the folded portion is formed at a current distribution waveform of a second harmonic wave and a third harmonic wave with respect to the fundamental wave. It is preferable to include the position of the intersection with the current distribution waveform. According to this configuration, since the folded portion of the radiating conductor corresponding to the vicinity of the intersection between the current distribution waveform of the second harmonic and the waveform of the third harmonic is electromagnetically coupled to the feeding point, the folded portion and the first terminal The frequency of the second harmonic can be adjusted substantially independently by changing the width of the gap between the electrodes. Further, the frequency of the third harmonic can be adjusted substantially independently by changing the conductor width of the folded portion.

  In the present invention, the radiation conductor includes first and second linear patterns formed on the top surface of the base body and extending in the longitudinal direction of the base body, and third and third lines formed on the bottom surface of the base body and extending in the longitudinal direction of the base body. A fourth linear pattern; a fifth linear pattern connecting one end of the first linear pattern and one end of the third linear pattern; and one end of the second linear pattern and the fourth linear pattern A sixth linear pattern that connects one end of the second linear pattern, and a seventh linear pattern that connects the third linear pattern and the other end of the fourth linear pattern. A first folded part is configured, the second folded part is configured by the fifth linear pattern, and the third folded part is configured by the sixth linear pattern. Rukoto is preferable.

  According to this configuration, it is possible to configure a radiating conductor having a structure in which a single strip-shaped conductor pattern is folded three times, particularly corresponding to the vicinity of the intersection of the second harmonic current distribution waveform and the third harmonic waveform. Since the seventh linear pattern is electromagnetically coupled to the feeding point, the frequency of the second harmonic wave is substantially changed by changing the width of the gap between the seventh linear pattern and the first terminal electrode. Can be adjusted independently. Further, the frequency of the third harmonic can be adjusted substantially independently by changing the conductor width of the seventh linear pattern.

  In the present invention, it is preferable to further include a chip inductor inserted in series between the power supply conductor and the power supply line. According to this configuration, a four-resonance antenna can be realized, and the resonance frequency of the fourth harmonic can be easily adjusted by changing the inductance of the chip inductor.

  In order to solve the above problems, an antenna device according to the present invention includes an antenna element and a printed circuit board on which the antenna element is mounted. The antenna element includes a base body made of a substantially rectangular parallelepiped dielectric; A feeding conductor formed on the first side surface orthogonal to the longitudinal direction of the base, and a single strip formed continuously over the top surface of the base, the second side surface facing the first side surface, and the bottom surface A radiation conductor formed of a conductor pattern; and a first terminal electrode formed on the bottom surface of the base and close to the first side surface so as to be connected to the power supply conductor, the radiation conductor having a folded structure And a first folded portion disposed opposite and in close proximity to the first terminal electrode via a gap having a predetermined width on the bottom surface of the base, and on the surface of the printed circuit board The antenna mounting region where the antenna element is mounted is provided with, directly below the antenna element to a rear surface of the printed circuit board is characterized in that the floating pattern is provided.

  Furthermore, in order to solve the above-mentioned problem, the frequency adjustment method for an antenna device according to the present invention is characterized in that the fundamental wave is changed by changing a width of a gap between the first folded portion and the first terminal electrode. The resonance frequency of the second harmonic with respect to is adjusted.

  Furthermore, the frequency adjustment method of the antenna device according to the present invention is characterized in that the resonance frequency of the third harmonic with respect to the fundamental wave is adjusted by changing the conductor width of the first folded portion.

  According to the present invention, an independent adjustment of each resonance frequency is easy, and a small and high-performance multi-resonance antenna can be provided.

FIG. 1 is a schematic perspective view showing a configuration of an antenna device according to a preferred embodiment of the present invention. FIG. 2 is a development view of the antenna element 10 shown in FIG. FIG. 3 is a schematic perspective view transparently showing a pattern layout on the printed circuit board 20 on which the antenna element 10 is mounted. FIG. 4 is a graph for explaining the current distribution on the radiation conductor 13. FIG. 5 is an equivalent circuit diagram of the antenna device 100 shown in FIG. FIG. 6 is a graph showing the frequency characteristics of the radiation efficiency of the antenna device 100 shown in FIG. FIG. 7 is a graph showing frequency characteristics of radiation efficiency of two types of antenna devices having different gap widths between the tip of the radiation conductor and the feed conductor. FIG. 8 is a graph showing the frequency characteristics of the radiation efficiency of the antenna device for the width of the gap between the seventh linear pattern constituting the folded portion and the first terminal electrode. FIG. 9 is a graph showing the frequency characteristics of the radiation efficiency of two types of antenna devices having different widths of the seventh linear pattern constituting the folded portion. FIG. 10 is a graph showing the frequency characteristics of the radiation efficiency of two types of antenna devices having different inductances of the chip inductor. FIG. 11 is a table showing the change amounts of the second harmonic, the third harmonic, and the fourth harmonic when the parameters of the antenna element are independently changed so that the change amount of the fundamental wave becomes 10 MHz.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic perspective view showing a configuration of an antenna device according to a preferred embodiment of the present invention. FIG. 2 is a development view of the antenna element 10 shown in FIG.

  As shown in FIGS. 1 and 2, the antenna device 100 includes an antenna element 10 and a printed board 20 on which the antenna element 10 is mounted. The antenna element 10 according to the present embodiment is a surface-mounted multi-resonant antenna, and is mounted in an antenna mounting region 23 formed on one main surface (front surface) 20a of the printed board 20.

  The antenna element 10 includes a base 11 made of a dielectric and a plurality of conductor patterns formed on the base 11. The base 11 has a rectangular parallelepiped shape in which the Y direction is the longitudinal direction, the X direction is the width direction, and the Z direction is the height direction. Among these, the upper surface 11a, the bottom surface 11b, and the two side surfaces 11c and 11d of the base body 11 are surfaces parallel to the Y direction, the side surfaces 11e and 11f are surfaces orthogonal to the Y direction, and the bottom surface 11b is mounted on the printed circuit board 20. Surface. The vertical direction of the antenna element 10 is determined based on the mounting state of the antenna element 10 on the printed circuit board 20, and the bottom surface 11 b of the antenna element 10 is in contact with the surface of the printed circuit board 20 when the antenna element 10 is mounted.

  Although it does not specifically limit as a material of the base | substrate 11, Ba-Nd-Ti type material (relative dielectric constant 80-120), Nd-Al-Ca-Ti type material (relative dielectric constant 43-46), Li—Al—Sr—Ti (relative permittivity 38 to 41), Ba—Ti based material (relative permittivity 34 to 36), Ba—Mg—W based material (relative permittivity 20 to 22), Mg—Ca— Ti-based materials (relative permittivity 19 to 21), sapphire (relative permittivity 9 to 10), alumina ceramics (relative permittivity 9 to 10), cordierite ceramics (relative permittivity 4 to 6), and the like can be used. . The substrate 11 is produced by firing these material powders using a mold.

What is necessary is just to select a dielectric material suitably according to the target frequency. As the relative permittivity ε _r increases, a greater wavelength shortening effect can be obtained, so that the length of the radiation conductor can be shortened, but the radiation efficiency decreases, so the relative permittivity ε _r does not necessarily have to be large. There is an appropriate value. Therefore, for example, when the target frequency is 2.4 GHz, it is preferable to use a material having a relative dielectric constant ε _r of about 5 to 40. According to this, it is possible to reduce the size of the base while ensuring sufficient radiation efficiency. Preferred examples of the material having a relative dielectric constant ε _r of about 5 to 40 include Mg—Ca—Ti dielectric ceramics. As the Mg—Ca—Ti dielectric ceramic, it is particularly preferable to use a Mg—Ca—Ti dielectric ceramic containing TiO ₂ , MgO, CaO, MnO, and SiO ₂ .

  The conductor pattern of the antenna element 10 is formed on the feeding conductor 12 formed on the side surface 11e of the base 11, the radiation conductor 13 formed on the top surface 11a, the side surface 11f, and the bottom surface 11b of the base 11, and the bottom surface 11b of the base 11. Terminal electrodes 14, 15a and 15b. These conductor patterns can be formed by applying an electrode paste material by a method such as screen printing or transfer and then baking under a predetermined temperature condition. Silver, silver-palladium, silver-platinum, copper, or the like can be used as the electrode paste material. In addition to this, the conductor pattern can also be formed by plating or sputtering.

  The radiating conductor 13 includes first and second linear patterns 13a and 13b formed on the upper surface 11a of the base 11, third and fourth linear patterns 13c and 13d formed on the bottom 11b of the base 11, and A fifth linear pattern 13e connecting one end of the first linear pattern 13a and one end of the third linear pattern 13c, and a first connecting the one end of the second linear pattern 13b and one end of the fourth linear pattern 13d. 6 linear patterns 13f, and a seventh linear pattern 13g connecting the other end of the third linear pattern 13c and the other end of the fourth linear pattern 13d.

  The first linear pattern 13a is provided along one side closer to the side surface 11c out of two sides parallel to the longitudinal direction of the upper surface 11a of the base 11, and one end thereof is connected to the fifth linear pattern 13e. The other end is connected to the feed conductor 12. The second linear pattern 13b is provided along one side of the two sides parallel to the longitudinal direction of the upper surface 11a of the base body 11 near the side surface 11d facing the side surface 11c, and one end of the second linear pattern 13b is the sixth side. The other end is open at a position close to the feeding conductor 12. Therefore, the first and second linear patterns 13a and 13b are parallel to each other, and the other end of the second linear pattern 13b is capacitively coupled to the feed conductor 12 through a gap having a width W1.

  Similar to the first and second linear patterns 13a and 13b, the third and fourth linear patterns 13c and 13d are also parallel to each other. The third linear pattern 13c is provided along one side closer to the side surface 11c out of two sides parallel to the longitudinal direction of the bottom surface 11b of the base 11, and one end thereof is connected to the fifth linear pattern 13e. The other end is connected to the seventh linear pattern 13g. The fourth linear pattern 13d is provided along one side of the two sides parallel to the longitudinal direction of the upper surface of the substrate 11 and close to the side surface 11d facing the side surface 11c, and one end thereof is a sixth straight line. The other end is connected to the pattern 13f, and the other end is connected to the seventh linear pattern 13g.

  The seventh linear pattern 13g connects the other ends of the third linear pattern 13c and the fourth linear pattern 13d, and thereby the first folded portion of the radiation conductor 13 is configured. The fifth linear pattern 13e connects one ends of the first linear pattern 13a and the third linear pattern 13c, and thereby a second folded portion of the radiation conductor 13 is configured. In addition, the sixth linear pattern 13f connects one ends of the second linear pattern 13b and the fourth linear pattern 13d, and thereby, a third folded portion of the radiation conductor 13 is configured. With the above configuration, the first linear pattern 13a, the fifth linear pattern, the third linear pattern, the seventh linear pattern, the fourth linear pattern, the sixth linear pattern, the Two linear patterns are connected in order, and a single band-like pattern having three folded portions is formed.

  In the present embodiment, the first terminal electrode 14 is an independent pattern, but the second and third terminal electrodes 15a and 15b are patterns that overlap with the third and fourth linear patterns 13c and 13d, respectively. The second terminal electrode 15a and the third linear pattern 13c are integrated, and the third terminal electrode 15b and the third linear pattern 13d are integrated. Therefore, the width of the third linear pattern 13c is slightly wider at the position where the second terminal electrode 15a is formed, and the width of the fourth linear pattern 13d is also slightly wider at the position where the third terminal electrode 15b is formed. It has become.

  As described above, the radiating conductor 13 is a band-shaped conductor pattern having a folded structure, and the first folded portion provided on the bottom surface 11b of the base body 11 is close to the first terminal electrode 14, and a gap having a predetermined width is formed. Via the first terminal electrode 14. Although details will be described later, in the antenna device 100 according to the present embodiment, the first folded portion of the radiating conductor 13 is located near the intersection of the current distribution waveform of the second harmonic and the third harmonic. The point is electromagnetically coupled. Therefore, the resonance frequency of the second harmonic and the third harmonic can be changed greatly, and the frequency adjustment becomes easy. The frequency adjustment of the second harmonic can be adjusted by changing the width W2 of the gap between the first folded portion and the first terminal electrode 14. Further, the frequency adjustment of the third harmonic wave can be adjusted by changing the width W3 of the seventh linear pattern 13g constituting the first folded portion.

  FIG. 3 is a schematic perspective view transparently showing a pattern layout on the printed circuit board 20 on which the antenna element 10 is mounted.

  As shown in FIG. 3, the printed circuit board 20 has a conductor pattern formed on the front and back surfaces of an insulating substrate 21 such as FR4 (glass epoxy). On the front surface 20a of the printed circuit board 20, an antenna mounting area 23, which is an area where mounting components for various circuits, wiring, ground patterns, and the like are excluded, is provided. The antenna mounting area 23 is a rectangular area that is slightly wider than the antenna element 10. The antenna mounting area according to the present embodiment is provided at the corner portion of the printed circuit board 20, and two sides are in contact with the edge 20 e of the printed circuit board 20. When the antenna mounting area 23 is provided at the corner portion of the printed circuit board 20, the two directions are free spaces where the printed circuit board (conductor pattern) does not exist when viewed from the antenna element 10, thereby increasing the radiation efficiency of the antenna. Can do.

  Three lands 24 to 26 are provided in the antenna mounting area 23. Terminal electrodes 14 to 16 of the antenna element 10 are connected to the lands 24 to 26, respectively. The land 24 is connected to the power supply line 28 via the chip inductor 27, but the lands 25 and 26 are floating patterns. The lands 25 and 26 are provided for mechanically fixing the end of the antenna element 10 by soldering.

  The back surface 20b of the printed circuit board 20 is provided with a ground clearance region 29 that is an insulating region having substantially the same shape in plan view as the antenna mounting region 23 on the front surface 20a side. Various mounting components are not mounted in the ground clearance region 29, and no wiring or ground pattern is provided. However, in the present embodiment, in the ground clearance region 29, a floating having substantially the same size as the antenna element 10 to be mounted is provided. A radiation suppression pattern 30 that is a pattern is formed. The radiation suppression pattern 30 is provided in order to suppress the influence of the conductor pattern on the back side of the printed circuit board 20 and the mounted components. The radiation conductor 13 is formed not only on the upper surface 11a and the side surface 11f of the base body 11 but also on the bottom surface 11b. Since this portion is in direct contact with the printed circuit board 20, it is affected by the configuration on the back surface side of the printed circuit board 20. Cheap. Therefore, the radiation suppression pattern 30 is provided to suppress the influence on the back side of the printed circuit board 20.

  As shown in FIG. 1, when the antenna element 10 is mounted on the printed circuit board 20, one end of the radiation conductor 13 is connected to the power supply line 28 via the power supply conductor 12, the land 24, and the chip inductor 27. A feeding current is supplied from the feeding line 28 to the radiation conductor 13, and the feeding current is radiated from the radiation conductor 13.

  FIG. 4 is a graph for explaining the current distribution on the radiation conductor 13, wherein the horizontal axis indicates the distance from the feeding point, and the vertical axis indicates the current amplitude.

  As shown in FIG. 4, when the antenna length is λ / 4 with respect to the wavelength λ of the fundamental wave WA1, the waveforms of the second harmonic and the third harmonic are WA2 and WA3, respectively. That is, the peak of the second harmonic wave WA2 is at the position of λ / 8, and the peak of the third harmonic wave WA3 is at the position of λ / 6. By combining such a region where the second and third harmonics are approximately in peak, that is, the vicinity of the intersection of the second and third harmonic waveforms with the vicinity of the feeding point. It becomes possible to adjust the frequency of the second harmonic and the third harmonic. Although the peak positions of the second harmonic and the third harmonic are slightly different, they can be independently adjusted by changing the width and position of the first folded portion.

  FIG. 5 is an equivalent circuit diagram of the antenna device 100.

  As shown in FIG. 5, the antenna element 10 on the printed circuit board 20 includes inductors L1 to L3 and capacitors C1 to C3. In addition, the feeding point P of the antenna element 10 is connected to the feeding line 28 via an inductor L 4 by a chip inductor 27 on the printed circuit board 20. The inductor L1 is configured by the first linear pattern 13a, the fifth linear pattern 13e, and the third linear pattern 13c of the radiating conductor 13, and the inductor L2 is configured by the first folded portion by the seventh linear pattern 13g. The inductor L3 is configured by a second linear pattern 13b, a sixth linear pattern 13f, and a fourth linear pattern 13d. Therefore, the inductors L1, L2, and L3 are connected in series.

  The capacitor C1 is a capacitance component due to the gap between the other end of the second linear pattern 13b (the tip of the radiation conductor 13) and the power supply conductor 12, and the capacitor C2 includes the first linear pattern 13g and the first linear pattern 13g. The capacitor C3 is a capacitance component due to the line width of the seventh linear pattern 13g.

  The inductor L1 and the capacitor C1 contribute to the resonance frequency of the fundamental wave, the inductor L2 and the capacitor C2 contribute to the resonance frequency of the second harmonic, and the inductor L3 and the capacitor C3 contribute to the resonance frequency of the third harmonic. Therefore, the resonance frequency of the second harmonic can be adjusted independently by changing the capacitance of the capacitor C2, and the resonance frequency of the third harmonic can be adjusted independently by changing the capacitance of the capacitor C3. it can.

  Further, the inductor L4 contributes to the frequency adjustment of the fourth harmonic. When it is desired to configure a four-resonance antenna, this can be realized by inserting the inductor L4 between the feeding point P and the feeding line 28 in series. The inductor L4 also affects the frequency of the second harmonic and the third harmonic, but the influence is very small. Therefore, even if the inductor L4 is mounted, the resonance frequency of the second harmonic or the third harmonic can be easily controlled. When configuring a four-resonance antenna, it is preferable to adjust the values of the capacitors C1 and C2 for the second harmonic and the third harmonic after setting the value of the inductor L4 first.

  In order to realize the double resonance characteristics using a single antenna conductor pattern, it is effective to use harmonics such as second harmonic and third harmonic. However, since the target double resonance frequency is not necessarily the second harmonic or the third harmonic, the multiple resonance frequency must be adjusted. Further, in order to construct a multi-resonant antenna having a plurality of resonance points within a wide frequency range from low frequency to high frequency on one chip, the band-shaped conductor pattern of the antenna must have a folded structure. In the case of the folded structure as in the present embodiment, the first folded portion approaches the feeding point, but this portion has a great influence on the double resonance characteristics of the antenna. In the present invention, it is possible to obtain desired double resonance characteristics by adjusting the position and shape of the first folded portion.

  FIG. 6 is a graph showing the frequency characteristics of the radiation efficiency of the antenna device 100, where the horizontal axis represents frequency (GHz) and the vertical axis represents radiation efficiency (dB).

  As shown in FIG. 6, the antenna device 100 is a multi-resonant antenna having resonance peaks in the 800 MHz band, 1.5 GHz band, 2.1 GHz band, and 2.5 GHz band. In this case, the 800 MHz band corresponds to the fundamental wave, the 1.5 GHz band corresponds to the second harmonic, the 2.1 GHz band corresponds to the third harmonic, and the 2.5 GHz band corresponds to the fourth harmonic. For the fundamental wave of 800 MHz band, the theoretical frequency of the second harmonic should be 1.6 GHz band, and the theoretical frequency of the third harmonic should be 2.4 GHz band. Since the folded portion of the radiation conductor 13 is provided in the vicinity of the intersection of the current distribution waveform and the third harmonic wave, and the folded portion and the feeding point are coupled, the second harmonic can be obtained by changing the position and shape of the folded portion. Alternatively, the frequency of the third harmonic can be greatly changed, and the frequency of the second harmonic or the third harmonic can be easily adjusted.

  As described above, in the antenna device 100 according to the present embodiment, the multi-resonant antenna is configured by the radiating conductor having a structure in which one band-shaped conductor pattern is folded three times. Since the first folded portion of the radiating conductor 13 corresponding to the vicinity of the intersection of the waveform and the third harmonic wave is electromagnetically coupled to the feeding point, the width of the gap between the folded portion and the first terminal electrode 14 By changing W2, the frequency of the second harmonic can be adjusted substantially independently. Further, the frequency of the third harmonic can be adjusted substantially independently by changing the conductor width W3 of the folded portion. Furthermore, by inserting a chip inductor 27 as a frequency adjusting element in series on the feed line 28, a resonance frequency corresponding to the fourth harmonic can be generated, and a four-resonance antenna can be realized.

  The present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention, and it goes without saying that these are also included in the present invention.

Example 1
An antenna device having the structure shown in FIG. 1 was prepared. The chip size of the antenna element 10 was 15 × 4 × 2 mm, and a material having a dielectric constant of 37 was used as the material of the base 11. The first and second linear patterns 13a and 13b of the radiation conductor 13 have a width of 1 mm, the third and fourth linear patterns 13c and 13d have a width of 1.2 mm, and the fifth and sixth linear patterns 13e and 13f have a width of 1 mm. The width was 1.5 mm, and the width of the seventh linear pattern 13 g was 1.2 mm. At this time, the width W1 of the gap between the tip of the radiation conductor 13 and the power supply conductor 12 was set to two types of 11.6 mm and 11.4 mm. Thereafter, the frequency characteristics of the radiation efficiency of the antenna were obtained. The result is shown in FIG. In the figure, “base” indicates a graph with W1 = 11.6 mm, and “change tip” indicates a graph with W1 = 11.4 mm. "SPEC" indicates the spec that the antenna should satisfy, and it is desirable that the graph of radiation efficiency should not intersect with this rectangular line.

  As shown in FIG. 7, when the tip of the radiating conductor 13 is brought close to the feeding conductor 12 and the gap width W1 is changed from 11.6 mm to 11.4 mm, all resonances from the fundamental wave to the fourth harmonic wave are obtained. Although the frequency peak shifted to the low frequency side, it was found that the shift amount of the fundamental wave was particularly large.

(Example 2)
The gap between the front end of the radiation conductor 13 and the power supply conductor 12 is fixed to 11.6 mm, and the gap between the seventh linear pattern 13g and the first terminal electrode 14 constituting the first folded portion. An antenna device having the same structure as that of Example 1 was prepared except that the width W2 of the two was 1.8 mm and 1.4 mm. And the frequency characteristic of the radiation efficiency of these antenna apparatuses was calculated | required on the same conditions as the said Example 1. FIG. The result is shown in FIG. In the figure, “base” indicates a graph with W2 = 1.8 mm, and “change interval” indicates a graph with W2 = 1.4 mm. "SPEC" indicates the spec that the antenna should satisfy.

  As shown in FIG. 8, when the seventh linear pattern 13g is brought close to the first terminal electrode 14 and the gap width W2 is changed from 1.8 mm to 1.4 mm, from the fundamental wave to the fourth harmonic wave. The peaks of all the resonance frequencies in FIG. 5 shifted to the low frequency side, but it was found that the shift amount of the second harmonic was particularly large.

(Example 3)
The width of the gap between the tip of the radiation conductor 13 and the power supply conductor 12 is fixed to 11.6 mm, and the width W3 of the seventh linear pattern 13g constituting the first folded portion is 1.2 mm and 1.8 mm. An antenna device having the same structure as in Example 1 was prepared except for the two types. And the frequency characteristic of the radiation efficiency of these antenna apparatuses was calculated | required on the same conditions as the said Example 1. FIG. The result is shown in FIG. In the figure, “base” indicates a graph of W3 = 1.2 mm, and “change interval” indicates a graph of W3 = 1.8 mm. "SPEC" indicates the spec that the antenna should satisfy.

  As shown in FIG. 9, when the width W3 of the first folded portion of the radiating conductor 13 is increased, the peaks of all the resonance frequencies from the fundamental wave to the fourth harmonic are shifted to the low frequency side. It was found that the shift amount of the frequency of the third harmonic and the fourth harmonic is large.

Example 4
Except that the width of the gap between the tip of the radiation conductor 13 and the power supply conductor 12 is fixed to 11.6 mm and the value of the inductor L4 composed of the chip inductor 27 is set to two types of 4.5 nH and 5.5 nH. An antenna device having the same structure as Example 1 was prepared. And the frequency characteristic of the radiation efficiency of these antenna apparatuses was calculated | required on the same conditions as the said Example 1. FIG. The result is shown in FIG. In the figure, “base” indicates a graph of L4 = 4.5 nH, and “inductance value change” indicates a graph of L4 = 5.5 nH. "SPEC" indicates the spec that the antenna should satisfy.

  As shown in FIG. 10, when the value of the inductor L4 composed of the chip inductor 27 is increased and changed from 4.5 nH to 5.5 nH, the frequency of the fundamental wave hardly changes, and the double wave and 3 It was found that the frequency of the harmonic wave decreased slightly, but the frequency decrease of the fourth harmonic wave was very large compared to them.

(Example 5)
The width W1 of the gap between the front end of the radiation conductor 13 and the power supply conductor 12 shown in the first embodiment, the seventh linear pattern 13g and the first terminal electrode constituting the first folded portion shown in the second embodiment The width W2 of the gap 14 and the width W1 of the seventh linear pattern 13g shown in the third embodiment and the inductor L4 composed of the chip inductor 27 are independent parameters, and each parameter is moved to change the fundamental wave by 10 MHz. The amount of change of the second harmonic, the third harmonic, and the fourth harmonic in the case of being made was determined. The result is shown in FIG.

  As shown in FIG. 11, when the width W1 of the gap between the tip of the radiation conductor 13 and the feed conductor 12 is changed, the change of each harmonic when the resonance frequency of the fundamental wave is changed by 10 MHz is observed. As a result, it was found that the change of the second harmonic was 0 MHz, the change of the third harmonic was 6 MHz, the change of the fourth harmonic was 6 MHz, and the change of the fundamental wave was the largest. Further, when the width W2 of the gap between the seventh linear pattern 13g and the first terminal electrode 14 is changed, when viewed in the same manner, the change of the second harmonic is a change of 284 MHz and the third harmonic. 19 MHz, the change of the 4th harmonic was 25 MHz, and the change of the 2nd harmonic was found to be the largest. In addition, when the width W1 of the seventh linear pattern 13g is changed, the second harmonic change is 1 MHz, the third harmonic change is 18 MHz, and the fourth harmonic change is 19 MHz. It was found that the change of the 4th harmonic was the largest, and the change of the 3rd harmonic was about the same. Further, when the value of the inductor L4 composed of the chip inductor 27 is changed, the change of the second harmonic is 55 MHz, the change of the third harmonic is 192 MHz, and the change of the fourth harmonic is 711 MHz. It turns out that the change of the fundamental wave is the largest.

DESCRIPTION OF SYMBOLS 10 Antenna element 11 Base | substrate 11a Base | substrate upper surface 11b Base | substrate bottom face 11c, 11d Base | substrate side surface 11e, 11f Base | substrate side surface 12 Feeding conductor 13 Radiation conductor 13a 1st linear pattern 13b 2nd linear pattern 13c 3rd linear pattern 13d Fourth linear pattern 13e Fifth linear pattern 13f Sixth linear pattern 13g Seventh linear pattern 14 First terminal electrode 15a Second terminal electrode 15b Third terminal electrode 20 Printed circuit board 20a Printed circuit board surface 20b Back surface 20e of printed circuit board Edge 21 of printed circuit board Insulating substrate 23 Antenna mounting area 24 First land 25 Second land 26 Third land 27 Chip inductor 28 Feed line 29 Ground clearance area 30 Radiation suppression pattern 100 Antenna device C1- C3 capacitor L 1-L4 Inductor P Feed point WA1 Fundamental wave WA2 Double wave WA3 Triple wave

Claims (7)

A substrate made of a substantially rectangular parallelepiped dielectric,
A power supply conductor formed on a first side surface orthogonal to the longitudinal direction of the substrate;
A radiation conductor composed of one strip-shaped conductor pattern formed continuously over the upper surface of the substrate, the second side surface facing the first side surface, and the bottom surface;
A first terminal electrode formed on the bottom surface of the base body and close to the first side surface so as to be connected to the power supply conductor;
The radiating conductor is a strip-shaped conductor pattern having a folded structure, and has a first folded portion that is disposed in close proximity to the first terminal electrode through a gap having a predetermined width on the bottom surface of the base. An antenna device. The total length of the radiation conductor is substantially equal to λ / 4 (λ is the wavelength of the fundamental wave);
2. The antenna device according to claim 1, wherein the formation position of the folded portion includes a position of an intersection of a second harmonic current distribution waveform and a third harmonic current distribution waveform with respect to the fundamental wave. The radiation conductor is
First and second linear patterns formed on the upper surface of the substrate and extending in the longitudinal direction of the substrate;
Third and fourth linear patterns formed on the bottom surface of the substrate and extending in the longitudinal direction of the substrate;
A fifth linear pattern connecting one end of the first linear pattern and one end of the third linear pattern;
A sixth linear pattern connecting one end of the second linear pattern and one end of the fourth linear pattern;
A seventh linear pattern connecting the third linear pattern and the other end of the fourth linear pattern;
The first folded portion is configured by the seventh linear pattern,
The second folded portion is configured by the fifth linear pattern,
The antenna device according to claim 1, wherein the third folded portion is configured by the sixth linear pattern.   The antenna device according to claim 1, further comprising a chip inductor inserted in series between the feeding conductor and a feeding line. An antenna element, and a printed circuit board on which the antenna element is mounted,
The antenna element includes a base body made of a substantially rectangular parallelepiped dielectric, a feed conductor formed on a first side surface perpendicular to the longitudinal direction of the base body, an upper surface of the base body, and a first surface facing the first side surface. A radiating conductor composed of one strip-like conductor pattern continuously formed on the two side surfaces and the bottom surface, and the bottom surface of the base body and formed close to the first side surface so as to be connected to the feeding conductor. The radiation conductor is a strip-like conductor pattern having a folded structure, and is disposed in close proximity to the first terminal electrode through a gap of a predetermined width on the bottom surface of the base. Having a first folded portion;
An antenna mounting area on which the antenna element is mounted is provided on the surface of the printed circuit board, and a floating pattern is provided on the back surface of the printed circuit board and immediately below the antenna element. An antenna device. A frequency adjustment method for an antenna device according to any one of claims 1 to 5,
The frequency adjustment of the antenna device, wherein a resonance frequency of a second harmonic with respect to the fundamental wave is adjusted by changing a width of a gap between the first folded portion and the first terminal electrode. Method. A frequency adjustment method for an antenna device according to any one of claims 1 to 5,
A method for adjusting a frequency of an antenna device, comprising: adjusting a resonance frequency of a third harmonic wave with respect to a fundamental wave by changing a conductor width of the first folded portion.

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