JP4742536B2 - Antenna device - Google Patents

Description

  The present invention relates to an antenna device suitable for use in various mobile communication devices, particularly terrestrial digital broadcast receiving terminals.

  The terrestrial digital broadcasting system (ISDB-T: Integrated Services Digital Broadcasting-Terrstrial, hereinafter referred to as a new broadcasting system) is scheduled to start broadcasting at the end of 2005 for mobile terminals. The new broadcasting system uses orthogonal frequency division multiplexing (OFDM), which is resistant to multipath interference, and allows multiple carriers to be arranged closely while suppressing mutual interference while partially overlapping. In addition, wide band reception is realized by efficiently using a narrow frequency band.

  In the new broadcasting system, one frequency channel (6 MHz) is divided into a maximum of three layers, thereby enabling separate broadcasting. In the new broadcasting system, a one-segment receiving function that uses one of 13 carriers in the same frequency channel as a receiving channel is adopted, compared with a full segment receiving system that uses the entire band of the frequency channel. It is excellent in anti-demodulation power, anti-frequency selective fading and the like. Due to these characteristics, the new broadcasting system has high reception even in various mobile communication devices such as portable television receivers (abbreviated as portable televisions), cellular phones, and portable information terminal devices (PDA: Personal Digital Assistat). It has the characteristic of having characteristics.

  By the way, a conventional mobile communication device, for example, a portable television 200 is provided with a telescopic rod antenna 201 whose antenna length resonates at a quarter wavelength as shown in FIG. The rod antenna 201 is a monopole antenna that excites electric power between an infinite ground and a linear antenna element, and exhibits the same behavior as a dipole antenna with an image current defined symmetrically with the ground. However, with the reduction in size and weight of mobile communication devices, it is difficult for the rod antenna 201 to secure a necessary antenna length of ¼ wavelength due to limitations due to mounting space and shape.

  The rod antenna 201 is based on an infinite ground, but when mounted on a mobile communication device, the size of the ground plate is also limited and can be generalized as shown in FIG. In the rod antenna 201, the antenna element 202 is rotatably combined with the ground plate 203 by a hinge mechanism, and the antenna element 202 is positioned coaxially with the ground plate 203 as shown in FIG. The antenna element 202 is positioned in parallel with the ground plate 203 as shown in FIG.

Since the ground plate 203 is finite, the rod antenna 201 has a large change in input characteristics depending on its size . FIG. 21 shows the result of analyzing the characteristics of the rod antenna 201 by the FDTD (Finite Difference Time Domain) method which is one of electromagnetic field analysis methods when the length L of the antenna element 202 is 40 mm. In FIG. 19, GV is the length of the ground plate 203 in the vertical direction, GW is the length of the ground plate 203 in the horizontal direction, and OG is the distance between the antenna element 202 and the ground plate 203.

  FIG. 20A shows the analysis result of the input characteristics of the rod antenna 201 in the state shown in FIG. 19A in which the antenna element 202 and the ground plate 203 are coaxially positioned. FIG. 19B shows the input characteristics of the rod antenna 201 when GV is 80 mm and GW is 40 mm in the state shown in FIG. 19B in which the antenna element 202 and the ground plate 203 are positioned in parallel. It is an analysis result.

  In the rod antenna 201, as is clear from the analysis result shown in FIG. 20A, the input characteristics are longer than the length L of the antenna element 202 and the horizontal length GW of the ground plate 203. Resonance occurs at a quarter wavelength of the length, depending greatly on the direction length GV. Accordingly, the frequency characteristics of the rod antenna 201 are greatly affected by the size and mounting state of the ground plate 203. The rod antenna 201 tends to increase in gain as the ground plate 203 increases in size, and the change is almost the same in the horizontal length GW and the vertical length GV.

  Further, in the rod antenna 201, as is clear from the analysis result shown in FIG. 20B, when the antenna element 202 and the ground plate 203 are close to each other, the capacitance component is increased and the frequency is increased, so that a constant interval is obtained. If it is separated, the length of the ground plate 203 is dominant and resonance occurs. Therefore, the rod antenna 201 is preferably used in a state where it protrudes to some extent from the device housing, which makes it difficult to reduce the size.

  On the other hand, in the mobile communication device, a helical antenna in which an antenna element is wound many times in a spiral shape with one wavelength diameter is used together with the rod antenna 201 described above. The helical antenna is characterized by having a wider frequency band and a wavelength shortening effect than the monopole antenna.

  In mobile communication devices, a so-called planar antenna such as a patch antenna in which an antenna pattern is directly formed on a wiring board is provided to reduce the thickness. The planar antenna has a problem that it is difficult to reduce the size of the device because a large-sized antenna pattern is required when the use frequency band is lowered. In addition, since the planar antenna is easily affected by a human body, a device housing, and the like, there is a problem that the reception state is not stable. As the planar antenna, a so-called meander pattern antenna is used in which the pattern length is secured by folding the antenna pattern in multiple layers. Such meander type antennas are characterized in that they can be thinned by forming an antenna pattern directly on a wiring board.

  Patent Document 1 discloses a chip antenna which is composed of a multilayer structure in which a complex three-dimensional metal pattern is sintered in a high dielectric material such as ceramic and emits electromagnetic waves by exciting a feeding current. The chip antenna can be formed smaller than the above-described planar antenna with respect to the use frequency band, and is used by being mounted on a circuit board together with electronic components and the like constituting the transmission / reception circuit.

JP 2002-252516 A

  On the other hand, in the new broadcasting system, the use frequency band is distributed over a very wide range of 470 MHz to 770 MHz in the UHF band, and an antenna that can receive a broadcast program with high sensitivity in a mobile communication device is extremely important. It is. In the new broadcasting system, there is a problem that the frequency band is narrow and the reception sensitivity is low in an antenna element generally mounted on a current mobile phone having a limited mounting space.

  In the rod antenna, a ground plate generally installed in a mobile phone casing is formed with a GW of about 40 mm and a GV of about 80 mm, and the lower limit of the usable frequency is about 800 MHz. About 90 mm. Therefore, the rod antenna can reduce the dependence of the ground plate by providing a sufficiently large ground plate as long as the mobile phone is used in the current use frequency band. However, in the case of a rod antenna, the dependency of the ground plate increases when the mobile phone has a specification that enables reception of a broadcast program based on a new broadcast system in which the lower limit value of the use frequency is about 470 MHz. For this reason, the rod antenna needs to have a length that can be greatly extended from the casing of the mobile phone, which deteriorates usability and increases the size of the device body.

  In addition, the helical antenna can be employed as an antenna for receiving a broadcast program of a new broadcasting system because the use frequency is widened as described above and the size is reduced by the wavelength shortening effect. However, the helical antenna requires a special process of winding the antenna element in a spiral shape, which increases costs and is difficult to reduce the thickness, and is not suitable for a built-in antenna mounted in a device casing. It is.

  Further, in the meander type antenna, it is possible to reduce the thickness of the device by forming the antenna pattern directly on the wiring board. However, in the meander type antenna, there is a limit in forming the pattern length on a small wiring board, and it is possible to secure a sufficient applied frequency band as an antenna for receiving a broadcast program of a new broadcasting system. Have difficulty. In the meander type antenna, it is possible to expand the band to some extent by using, for example, a switch or a varicap, but there is a limit to the band expansion.

Chip antennas are extremely small in size even when a plurality of chip antennas are mounted side by side on a wiring board , so that it is possible to ensure downsizing and thinning of equipment. However, since the chip antenna is relatively expensive and requires a process of mounting on the wiring board, the cost of the device is greatly increased.

Accordingly, the present invention provides an antenna device suitable for use in a mobile communication device that is manufactured in a small size by a simple manufacturing process, has a wideband characteristic or a high sensitivity reception characteristic, and has a reception function such as terrestrial digital broadcasting. The purpose is to do.

The antenna device according to the present invention that achieves the above-described object uses a vertically long rectangular double-sided board in which a conductive foil is provided on the first main surface and the second main surface of a substrate material obtained by mixing a magnetic material with a dielectric material. The antenna pattern is formed by a printed circuit board technique in which a predetermined pattern forming process is applied to the conductor foils on both main surfaces. The antenna device is composed of a large number of first unit antenna patterns, a large number of second unit antenna patterns, a large number of via holes, a power supply terminal portion, and a power supply pattern formed on a double-sided board. In addition, an antenna pattern having a sufficient antenna length is formed on a double-sided substrate of a large size, and a wavelength shortening effect is obtained by the material characteristics of the substrate, so that the size and thickness can be reduced, and broadband characteristics can also be achieved.

The antenna device performs a predetermined pattern forming process on the conductor foil provided on the first main surface of the double-sided substrate, and is longitudinally independent from each other in the left and right regions sandwiching the center in the width direction on the first main surface. parallel department to form a plurality of first unit antenna pattern. The first unit antenna pattern has a vertical pattern portion facing each other at the center portion of the double-sided board, and is bent toward the side at the upper end of the vertical pattern portion, and the tip portion is positioned in the vicinity of the side edge portion of the double-sided board. An upper horizontal pattern portion, and a lower horizontal pattern portion which is bent in a lateral direction at the lower end of the vertical pattern portion and is opposed to the front end portion of the upper horizontal pattern portion which is adjacent to the end portion in the length direction. In addition, the vertical pattern part is constituted by a substantially U-shaped folded pattern with the center side open in the area between the upper horizontal pattern part and the lower horizontal pattern part at each halfway point, and the side edge side of the double-sided board is opened. It consists of a pattern whose basic shape is a substantially U-shaped folded shape that is symmetrical in the left and right side regions. The antenna device performs a pattern forming process on the conductive foil provided on the second main surface of the double-sided substrate, thereby forming a plurality of second unit antenna patterns that are arranged in the length direction independently of each other. The second unit antenna pattern is positioned on the second main surface at one end side corresponding to the upper horizontal pattern portion of the first unit antenna pattern formed in one of the left and right side regions, and the other end side is the other of the left and right side regions. It consists of a pattern positioned corresponding to the lower horizontal pattern portion of the first unit antenna pattern formed in the region .

In the antenna device, via holes are formed through the first main surface and the second main surface along the side edges of the double-sided board with a predetermined pitch in the length direction, and each is internally connected. Is given. The via hole includes a front end portion of the upper horizontal pattern portion and a front end portion of the second unit antenna pattern that face each other and a front end portion of the lower horizontal pattern portion that faces the first unit antenna pattern and the second unit antenna pattern. The first unit antenna pattern and the second unit antenna pattern facing each other are formed in positions corresponding to the other end, and the opposing patterns of the first unit antenna pattern and the second unit antenna pattern are alternately connected to each other. In the antenna device, the feeding terminal portion is formed at one end portion in the length direction of the double-sided board. In the antenna device, the power supply pattern is subjected to a predetermined pattern forming process on the conductive foil provided on the first main surface or the second main surface of the double-sided substrate, and one end portion is connected to the power supply terminal portion and the other end portion is connected to the power supply terminal. It is connected to the first unit antenna pattern or the second unit antenna pattern formed on one end side in the length direction of the double-sided board on which the portion is formed.

The antenna device includes a lower horizontal pattern of a first unit antenna pattern formed opposite to an upper horizontal pattern portion or a lower horizontal pattern portion of the first unit antenna pattern formed on one region side of the double-sided substrate and the other region side. The whole or the top horizontal pattern portion was connected in series by connecting the opposing second unit antenna pattern and the via hole, and one end side was connected to the feeding terminal portion and the other end side was opened. A three-dimensional helical antenna pattern is formed in the first main surface and the second main surface of the double-sided board. In the antenna device, a magnetic field having an opposite phase is generated at each of the opposing folded portions of each first unit antenna pattern, and a minute multiple loop is formed on the first main surface of the double-sided substrate, and energy is accumulated. In the antenna device, the accumulated energy is in a dominant state with more magnetic field energy distributed inside than electric field energy. In the antenna device, an effect of shortening the wavelength by the cooperative action with the magnetic material mixed with the substrate material is achieved, and a reduction in size is achieved by shortening the antenna pattern.

According to the antenna device of the present invention, a large number of first unit antenna patterns formed on the first main surface of the insulating substrate and a large number of second unit antennas formed on the second main surface by simple printed circuit board technology. The patterns are alternately connected to each other through via holes to form a three-dimensional helical antenna pattern, and at least each first unit antenna pattern is formed to have a large number of folded portions constituting a multiple loop. According to the antenna device, magnetic field energy is accumulated more predominately than electric field energy inside the multiple first unit antenna patterns, and wavelength shortening can be efficiently achieved by the cooperative action with the magnetic material mixed with the substrate material. It becomes like this. According to the antenna device, it is possible to reduce the cost and to have a wide band characteristic and to be miniaturized by a wavelength shortening effect, and is suitably used for various mobile communication devices.

  Hereinafter, an antenna device 1 shown in the drawings as an embodiment of the present invention will be described in detail. The antenna device 1 is used for various mobile communication devices such as a mobile TV, a mobile phone, or a portable information terminal device, for example, and has a very wide distribution of the use frequency band of 470 MHz to 770 MHz in the UHF band together with conventional reception characteristics. It is possible to receive broadcast programs with high sensitivity corresponding to the new broadcasting system. In the antenna apparatus 1, the new broadcasting system performs not only the above-described UHF band but also a broadcast program in the VHF band, so that it is possible to meet the demand for further miniaturization. The antenna device 1 is configured to be small and thin by forming an antenna pattern to be described later on a vertically long rectangular double-sided substrate 2.

  As shown in FIG. 1, the antenna device 1 includes a plurality of first unit antenna patterns 3a to 3n (hereinafter referred to as individual units) formed independently on the first main surface 2a of the double-sided substrate 2 with the same pitch. The first unit antenna pattern 3 is generically referred to except for the case described in FIG. The antenna device 1 includes a large number of second unit antenna patterns 4a to 4n (in the following, unless otherwise described) that are independently formed on the second main surface 2b of the double-sided substrate 2 with the same pitch. And collectively referred to as a second unit antenna pattern 4).

  The antenna device 1 includes a plurality of first via holes 5a to 5n (hereinafter referred to as “first” unless otherwise described) that are formed along the first side edge 2c of the double-sided substrate 2 with the same pitch. And collectively referred to as via hole 5). The antenna device 1 includes a plurality of second via holes 6a to 6n (hereinafter, unless otherwise described), which are formed along the second side edge 2d of the double-sided substrate 2 with the same pitch. And collectively referred to as via hole 6). In the antenna device 1, the first via hole 5 and the second via hole 6 are opposed to each other, and are formed on the double-sided substrate 2 with the same pitch as the second unit antenna pattern 4.

  In the antenna device 1, third via holes 7 are formed on the second side edge 2 d side of the double-sided substrate 2 with the same pitch with respect to the lowermost second via hole 6 a. In the antenna device 1, a power feeding pattern 8 extending from the third via hole 7 to the lower end portion is formed on the double-sided substrate 2, and a power feeding terminal portion 9 is integrally formed at the lower end portion of the power feeding pattern 8. Yes. The antenna device 1 is connected to a ground 10 provided with a power feeding pattern 8 on the main device side via a power feeding terminal portion 9.

  As will be described in detail later, the antenna device 1 has both end portions of each second unit antenna pattern 4 opposed to both end portions of each first unit antenna pattern 3 via first via holes 5 and second via holes 6. The first main surface 2a and the second main surface 2b of the double-sided substrate 2 are alternately connected. The antenna device 1 is configured to form a three-dimensional helical antenna pattern as a whole by forming an antenna pattern over the first main surface 2a and the second main surface 2b of the double-sided substrate 2.

The double-sided board 2 is generally used in various conventional electronic devices and the like, and a board material in which a conductor such as a copper foil is pasted on both sides of an insulating board is used. For example, a first unit antenna pattern 3 and a second unit antenna pattern 4 having a predetermined shape are formed by performing a pattern forming process such as a lithography process on the second main surface 2b to remove unnecessary conductors. The double-sided substrate 2 is subjected to drilling or laser processing on the insulating substrate to form through holes at appropriate positions, and the through holes are subjected to a conductive process in the holes by plating or the like. A first via hole 5 and a second via hole 6 are formed. The double-sided board 2 can efficiently form a desired circuit pattern without requiring large-scale equipment and precision technology, and various electronic components are mounted on the double-sided board 2.

As shown in FIGS. 1 and 2, the first unit antenna pattern 3 is formed in the left and right side regions in the length direction with the center in the width direction sandwiched between the first main surface 2 a of the double-sided substrate 2. It consists of a folding pattern that folds in a substantially U-shape. The first unit antenna pattern 3 has U-shaped open portions located on the outer sides in the left and right regions, and the opposing pattern in the left and right regions is one pitch of the first via hole 5 and the second via hole 6 with respect to the vertical direction. It is formed by minute displacement. That is, the first unit antenna pattern 3 is the left edge portion of the double-sided board 2 as described by referring to the first unit antenna pattern 3a formed at the bottom of the left region with reference to FIG. The horizontal lower side 3a2 is formed to the vicinity of the center with the first end 3a1 as the first end 3a1, and the vertical side 3a3 is connected to the vertical by bending the lower side 3a2 in the height direction at a position near the center. An upper side 3a4 parallel to the lower side 3a2 at the upper end of the side 3a3 is bent in a horizontal direction, and the upper side 3a4 is formed as a second end 3a5 so as to face the first end 3a1. It is formed in a shape. In the first unit antenna pattern 3a, the first end 3a1 is connected to the lowermost first via hole 5a, and the second end 3a5 is connected to the second first via hole 5b.

In addition, the first unit antenna pattern 3 is configured such that the first unit antenna pattern 3b formed at the bottom of the right region adjacent to the formation region of the first unit antenna pattern 3a described above is the upper side portion of the first unit antenna pattern 3a. A horizontal lower side 3b2 is formed up to the vicinity of the center with the vicinity of the right edge of the double-sided substrate 2 as the first end 3b1 at the same height as 3a4. The first unit antenna pattern 3b is bent in the height direction from the lower side 3b2 at a position near the center, and a vertical side 3b3 is continuously provided. An upper side parallel to the lower side 3b2 at the upper end of the vertical side 3b3 3b4 is bent in the horizontal direction, and the upper side 3b4 is formed in a U-shape opposite to the first end 3b1 as the second end 3b5. Let 2 end 3b5. In the first unit antenna pattern 3b, the first end 3b1 is connected to the second via hole 6a at the lowest stage, and is connected to the second via hole 6b at the 52nd stage of the second end 3b.

In the first unit antenna pattern 3, the first unit antenna pattern 3c of the second stage in the left region is the first unit antenna pattern 3b described above from the substantially same height position as the upper side 3b4 of the lowermost first unit antenna pattern 3b in the right region. It is formed with the same shape as the unit antenna pattern 3a. The first unit antenna pattern 3 is formed so that the mutual interval and the interval between the first end 3a1 (3b1) and the second end 3a5 (3b5) are substantially equal. Therefore, the first unit antenna pattern 3 is alternately formed on the first main surface 2a of the double-sided substrate 2 with the direction of the left and right regions changed and shifted by one pitch of the via holes 5 (6) with respect to the vertical direction. Is done.

Second unit antenna pattern 4, the second main surface 2b of the double-sided substrate 2, the first unit antenna pattern 3 formed relative to the left and right regions of the first main surface 2a side as described above (3a, 3b) Each of the lower side portions 3a2 (3b2) and the upper side portions 3a4 (3b4) are respectively opposed to and parallel to each other. The second unit antenna pattern 4 has a length equal to the opposing distance between the first via hole 5 and the second via hole 6 that face each other, and the second unit antenna pattern 4 faces the opposite ends as shown in FIG. It is connected to the first via holes 5 and the second via hole 6. As shown in FIG. 2B, the lowermost second unit antenna pattern 4a has one end connected to the lowermost first via hole 5a and the other end connected to the third via hole 7. .

  The first via holes 5, the second via holes 6 and the third via holes 7 are formed on the through holes formed in the double-sided substrate 2 as described above by conducting a conductive treatment in the holes. The second main surface 2b is electrically connected. As described above, the first via holes 5 and the second via holes 6 alternately connect the end portions of the first unit antenna pattern 3 and the second unit antenna pattern 4 which are opposed to each other. Each first via hole 5 and each second via hole 6 connect each first unit antenna pattern 3 and each second unit antenna pattern 4 facing each other in series. As described above, the lower side 3b2 of the lowermost second unit antenna pattern 4a is connected to the third via hole 7 on the second main surface 2b, and one end of the feed pattern 8 is connected to the first main surface 2a. Is done.

  In the antenna device 1, as described above, each first unit antenna pattern 3 forms a kind of meander pattern on the first main surface 2 a of the double-sided substrate 2, and each first via hole 5 and each second via hole 6 are interposed. The second main surface 2b is folded by the second unit antenna pattern 4. Therefore, the antenna device 1 includes the first main surface 2a and the second main surface of the double-sided substrate 2 by the first unit antenna pattern 3, the second unit antenna pattern 4, the first via holes 5, and the second via holes 6. A helical antenna pattern having a predetermined overall length around 2b is formed.

  Based on the basic configuration described above, for example, the first unit antenna pattern 3 and the second unit antenna pattern 4 are formed in a region having a length of 40 mm on the first main surface 2a and the second main surface 2b of the double-sided substrate 2, The antenna device 1 is manufactured with a pitch of 2 mm and a width of 5 mm between each first unit antenna pattern 3 and each second unit antenna pattern 4. The antenna device 1 was analyzed for antenna characteristics, which will be described later, using Microwave-Studio manufactured by CST (COMPUTER SIMULATION TECHNOLOGY).

  The antenna device 1 includes an odd-numbered first unit antenna pattern 3 formed in the left region and an even-numbered first unit antenna pattern 3 formed in the right region as schematically shown in part in FIG. The first magnetic field 11 and the second magnetic field 12 having opposite phases are generated at the corner portions 100a to 100n of the vertical side, the upper side, and the lower side that face each other. The antenna device 1 is operated as an antenna when the first magnetic field 11 and the second magnetic field 12 form a minute loop in each of them to generate a displacement current in the double-sided substrate 2.

When the antenna device 1 is used by being arranged on the same axis as that of the ground 10 as shown in FIG. 3A, an input based on the size of the ground 10 is shown in FIG. The change in characteristics is shown. In the antenna device 1, as described above, a displacement current is generated for each minute loop and the antenna operation is performed. Therefore, in comparison with a monopole antenna in which current is distributed over the entire length of the conventional antenna device 1. An analysis result having a small dependence on the change in the size of the ground (longitudinal length GV ) can be obtained.

Further, when the antenna device 1 is used in a state parallel to the ground 10 as shown in FIG. 4A, the analysis result of the dependency on the ground 10 is shown in FIG. Indicates the change in input characteristics. The antenna device 1 is arranged in parallel with a ground having a GV of 80 mm and a GW of 40 mm. In the antenna device 1, since each minute loop has a structure orthogonal to the ground 10, the dependency on the change in the size of the ground (longitudinal length GV ) as compared with the monopole antenna is also obtained in this usage pattern. Small analysis results can be obtained.

FIG. 6 shows the input characteristics of the antenna device 1 when the matching circuit 13 shown in FIG. 5 is connected and the constants of the single unit and the matching circuit 13 are changed. The matching circuit 13 is a general circuit that is interposed between the antenna device and the tuner. The matching circuit 13 is connected to the antenna device 1 at one end and is grounded at the other end. It consists of a series circuit of a second coil 15 and a capacitor 16 connected to the device 1 and having the other end connected to the input end of the tuner. In the matching circuit 13, a first matching circuit 13A and a second matching circuit 13B having different specifications are connected between the antenna device 1 and the tuner, and the first matching circuit 13A and the second matching circuit 13B have an appropriate switch structure. Can be switched.

The first matching circuit 13A includes, for example, a first coil 14 inductance 15 nH, the second coil 15 inductance 3.3 nH, the first circuit constant which is set by a combination of a capacitor 16 of capacitance 3 pH. The second matching circuit 13B has a second circuit constant set by a combination of, for example, an 18 nH first coil 14, a 1.2 nH second coil 15, and a 3pH capacitor 16. Incidentally, the matching circuit 13, a first matching circuit 13A not only configuration Ru by Ri switched to the second matching circuit 13B to switch, for example, configured for switching by switching each element individually also be employed.

When the antenna device 1 is used alone without being connected to the matching circuit 13, as shown by a solid line in FIG. 6, an input characteristic having a VSWR (Voltage Standing Wave Ratio) of 3 or less is reduced. Obtained in a frequency band from 571 MHz to about 670 MHz. Further, the antenna device 1 has a bandwidth with a VSWR of 3 or less of about 100 MHz, and can achieve a wider bandwidth than a monopole antenna. Meanwhile, the antenna device 1, in order to use the frequency band is received in good condition broadcast program over the entire region of the new broadcasting system which is 470MHz~770MHz the UHF band, the bandwidth is somewhat insufficient.

  In the antenna device 1, the first matching circuit 13A and the second matching circuit 13B are selectively connected, so that the use frequency band of the new broadcasting system can be received in a good state over the entire area. In the antenna device 1, by connecting the first matching circuit 13A, the operation of the first matching circuit 13A can be performed even in the band of 470 MHz to 571 MHz where it is difficult to perform good reception alone as shown by the broken line in FIG. Therefore, it is possible to cope with good reception. In the antenna device 1, the second matching circuit 13 </ b> B is connected so that the second matching circuit 13 </ b> B is connected to the 670 MHz to 770 MHz band in which it is difficult to perform good reception alone as shown by the chain line in FIG. 6. Good reception can be achieved by the action of the circuit 13B.

Next, with respect to the antenna device 1, the frequency characteristics of the antenna gain in the horizontal plane and the predetermined frequency in a anechoic chamber using a rod antenna having a length of about 100 mm and a helical antenna, which are generally used in conventional portable televisions, as a comparative example. The radiation characteristics were confirmed by measuring the vertical polarization and the horizontal polarization. As for the antenna device 1, the first antenna device 1 </ b > A having a length of 40 mm and the second antenna device 1 </ b> B having a length of 30 mm are common to a double-sided substrate having a thickness of 3.2 mm with a pitch of 2 mm and a pattern width of 5 mm. Antenna gain and directivity were measured. The measurement results are shown in FIGS.

  FIG. 7 shows the frequency characteristics of the antenna gain of each antenna device. In the figure, a1 is the maximum gain of the antenna device 1A (total length 40 mm), a2 is the average gain, b1 is the maximum gain of the antenna device 1B (total length 30 mm), b2 is the average gain, and c1 is the helical of the comparative example. The maximum gain of the antenna, c2 is the average gain, d1 is the maximum gain of the rod antenna of the comparative example, and d2 is the average gain. As is clear from the figure, the antenna device 1A obtains −7 dBi at the maximum gain and −9 dBi at the average gain. Further, as is clear from the figure, the antenna device 1B obtains −9 dBi at the maximum gain and −12 dBi at the average gain. Since the antenna devices 1A and 1B have a large difference in antenna length, the maximum gain and the average gain are both lower than those of the rod antenna, but the gain is larger than that of the helical antenna.

  FIG. 8 shows the horizontal plane directivity of each antenna device. In the figure, the a line represents the antenna device 1A, the b line represents the antenna device 1B, the c line represents the rod antenna, and the d line represents the helical antenna. FIG. 4A shows the vertical polarization characteristics at 470 MHz, and FIG. 4B shows the horizontal polarization characteristics at 470 MHz. FIG. 4C shows the vertical polarization characteristic at 600 MHz, and FIG. 4D shows the horizontal polarization characteristic at 600 MHz. Further, FIG. 4E shows the vertical polarization characteristic at 700 MHz, and FIG. 4F shows the horizontal polarization characteristic at 700 MHz. As is apparent from these drawings, the antenna device 1A and the antenna device 1B have directivity equivalent to that of a rod antenna or a helical antenna, despite being small.

  As described above, the antenna device 1 exhibits good antenna characteristics without being affected by the size of the ground 10 even if the overall length is as small as 30 mm or 40 mm. The antenna device 1 can be mounted in a so-called palm-sized mobile communication device such as a mobile phone or a PDA to receive a broadcast program of a wideband new broadcasting system in a good state while maintaining a small size. And The antenna device 1 is extremely inexpensive because it is manufactured by a general printed circuit board technology, and the mounting efficiency of the main device can be improved by simultaneously mounting transmission / reception circuit components and the like on the substrate. Try to reduce the size.

  In the antenna device 1 described above, the first via hole 5 includes the meander-type first unit antenna pattern 3 formed on the first main surface 2a of the double-sided substrate 2 and the second unit antenna pattern 4 formed on the second main surface 2b. And the second via hole 6 constitute a three-dimensional helical antenna pattern. The present invention is not limited to such a configuration, and various antenna patterns surrounding the first main surface 2a and the second main surface 2b of the double-sided substrate 2 may be formed.

  FIG. 9 is a diagram analyzing various antenna patterns formed around the first main surface 2a and the second main surface 2b of the double-sided substrate 2 and their antenna lengths. In the antenna apparatus, the antenna length is the length W1 of each first unit antenna pattern 3, the length W2 of each second unit antenna pattern 4, the lengths of the first via hole 5 and the second via hole 6, that is, the double-sided substrate 2. The thickness H is determined. Representative antenna patterns 20A to 20D configured between two first via holes 5 and one second via hole 6 are shown in a list. The antenna pattern 20D is the same as the first unit antenna pattern 3 and the second unit antenna pattern 4 of the antenna device 1 described above.

The antenna pattern 20A forms a helical pattern by the route of the first via hole 5a-first unit antenna pattern 3-second via hole 6-second unit antenna pattern 4- first via hole 5b. Therefore, the antenna pattern 20A has a total length of 3H + 2√ ( 2V + 2W ) when the helical pitch is 2V.

  In the antenna pattern 20B, the first unit antenna pattern 3 and the second unit antenna pattern 4 are substantially L-shaped, respectively, and the second via hole 6a-second unit antenna pattern 4-first via hole 5-first unit. Antenna pattern 3—A helical pattern is formed by the route of the second via hole 6b. Therefore, the antenna pattern 20B has a total helical pattern length of 3H + 2V + 2W.

  In the antenna pattern 20C, the first unit antenna pattern 3 and the second unit antenna pattern 4 each have a substantially crank shape, and like the antenna pattern 20B, the second via hole 6a-second unit antenna pattern 4-first via hole. 5—First unit antenna pattern 3—A helical pattern is formed by the route of the second via hole 6b. Therefore, in the antenna pattern 20C, the total length of the helical pattern is 3H + 2V + 3W.

  As described above, in the antenna pattern 20D, the first unit antenna pattern 3 is substantially U-shaped, and the second via hole 6a-second unit antenna pattern 4a-first via hole 5a-first unit antenna pattern 3a- A helical pattern is formed by the first via hole 5b-second unit antenna pattern 4b-second via hole 6b. Therefore, the antenna pattern 20D has a total helical pattern length of 6H + 2V + 6W-3G (G is an interval between the left and right first unit antenna patterns).

  For each of the antenna patterns 20 </ b> A to 20 </ b> D described above, FIG. 10 shows a change characteristic of the helical length with respect to each helical pitch, and FIG. 11 shows a change characteristic of the helical length with respect to the thickness of the double-sided substrate 2. As is clear from these drawings, each of the antenna patterns 20A to 20D has an increased helical pattern length with respect to the total length of the antenna and the thickness of the double-sided substrate 2. Therefore, each of the antenna patterns 20A to 20D can obtain a wavelength shortening effect and reduce the size and thickness of the main device using the thin double-sided substrate 2. In particular, the antenna pattern 20D has a structure in which the first unit antenna pattern 3 is formed as a miranda pattern in the left and right regions of the double-sided substrate 2, so that the helical pattern length can be significantly increased and the wavelength can be shortened.

  In the antenna device 1, a three-dimensional helical antenna pattern is formed by the first unit antenna pattern 3 and the second unit antenna pattern 4 so as to go around the first main surface 2 a and the second main surface 2 b of the double-sided substrate 2. Formed. In the antenna device 1, as described above, the antenna length is secured by making the pitch of the helical pattern dense, so that the antenna device 1 can be thinned. In the antenna device 30 shown in FIG. 12 as the second embodiment, a large number of first unit antenna patterns 32 are independently formed on the first main surface 31a of the double-sided substrate 31 with the same pitch. In addition, a large number of second unit antenna patterns 33 are independently formed at the same pitch on the second main surface 31b.

  The antenna device 30 uses, for example, a double-sided board 31 having a thickness of about 2 mm, and a plurality of first via holes 34 are formed along the first side edge of the double-sided board 31 with the same pitch p. In addition, a large number of second via holes 35 are formed along the second side edge with the same pitch p. In the antenna device 30, the first via hole 34 and the second via hole 35 are formed on the double-sided substrate 2 with the same pitch and spaced apart from each other in the width direction. It is formed with a pitch width of about 1/2 of the pitch of the via holes 5 and the second via holes 6.

  As shown in FIG. 12 (A), the first unit antenna pattern 32 is formed on both sides of the first main surface 31a of the double-sided substrate 31 so as to hold the opposing distance d across the center in the width direction. The first unit of the antenna device 1 described above has a basic shape that is formed in a U-shape as a basic shape, and in which the U-shaped open portions are located on the outer sides in the left and right regions, and is offset in the vertical direction. The same as antenna pattern 3. In the first unit antenna pattern 32, a lower side portion 32a2 is integrally connected in a horizontal direction from a first end portion 32a1 connected to the first via hole 34 or the second via hole 35 (first via hole 34a in the drawing).

  The first unit antenna pattern 32 includes a first vertical portion 32a3 that is bent in the height direction at the tip of the lower side portion 32a2 and has a length of about 1 / 2p. A first folded side portion 32a4 that is bent toward the side from the tip and faces the lower side portion 32a2 in parallel is integrally provided. The first unit antenna pattern 32 includes a second vertical portion 32a5 having a length of about ½p as a result of the first folded side portion 32a4 being bent in the height direction in the vicinity of the first via hole 34 and the second via hole 35. Are integrally provided, and a second folded side portion 32a6 that is bent from the tip of the second vertical portion 32a5 toward the center and faces the first folded side portion 32a4 in parallel is integrally provided.

  The first unit antenna pattern 32 has a third vertical portion 32a7 that is bent in the height direction at the tip of the second folded side portion 32a6 and has a length of about 1 / 2p. An upper side portion 32a8 that is bent toward the side from the tip of the portion 32a7 and faces the second folded side portion 32a6 in parallel is integrally provided. The first unit antenna pattern 32 has a length in which the upper side portion 32a8 is positioned on the axis of each first via hole 34 or each second via hole 35, and is bent at the tip portion to be in contact with the third vertical portion 32a7. The opposed fourth vertical portions 32a9 are integrally connected. In the first unit antenna pattern 32, a second end 32a10 connected to the next first via hole 34 or the second via hole 35 (first via hole 34b in the drawing) is integrally formed at the tip of the fourth vertical portion 32a9. It becomes.

Each of the first unit antenna patterns 32 configured as described above has a U-shaped basic shape like the first unit antenna pattern 3 of the antenna device 1 described above. However, the first unit antenna pattern 32 has a lower side portion 32a2 and an upper side portion 32a8. Further, it is characterized by a shape in which a U-shaped folded portion is continuously provided in between. The pattern length of each first unit antenna pattern 32 is extended by a length corresponding to the folded portion and the fourth vertical portion 32a9 as compared to the first unit antenna pattern 3 of the antenna device 1 described above. The first unit antenna pattern 32 is formed on the first main surface 31a of the double-sided substrate 31, and the first unit antenna pattern 32b in the right region opposite to the first unit antenna pattern 32a in the left region is connected to the first via hole 34b. formed drives out symmetrical shape with respect to the above-described pattern of the second via hole 35b as starting at the same height position.

Each second unit antenna pattern 33 is formed on the second main surface 31 b of the double-sided substrate 31 so as to face each of the first unit antenna patterns 32 described above. As shown in FIG. 12B, the second unit antenna pattern 33 is formed as a horizontal pattern having a substantially crank shape in a region having the same width as the pitch p of the first via holes 34 or the second via holes 35. . Specifically, the second unit antenna pattern 33 is connected to the first via hole 34a to which the first end 32a1 of each first unit antenna pattern 32 described above is connected on the second main surface 31b side. The first vertical portion 33a2 having a length of about ½p is integrally connected.

  In the second unit antenna pattern 33, a first horizontal side portion 33a3 having a length substantially equal to the lower side portion 32a2 of the first unit antenna pattern 32 is integrally connected in the horizontal direction from the tip of the first vertical portion 33a2. The second unit antenna pattern 33 has a pitch p in the range of the facing distance d between the adjacent first unit antenna patterns 32 at the front end of the center position of the double-sided substrate 31 where the first horizontal offset portion 33a3 is located. The inclined side part 33a4 which inclines is continuously provided integrally. The second unit antenna pattern 33 is integrally provided with a second horizontal side 33a5 that is substantially equal in length to the upper side 32a8 of the first unit antenna pattern 32 in the left region at the tip of the inclined side 33a4. . The second unit antenna pattern 33 has a second horizontal portion 33a5 whose tip is located on the axis of each first via hole 34 or each second via hole 35, and a second vertical portion that faces the first vertical portion 33a2 from the tip. 33a6 is continuously provided integrally, and the tip end portion of the second vertical portion 33a6 is connected to the second via hole 35a as the second end portion 33a7.

  The 2nd unit antenna pattern 33 comprised as mentioned above is the same as that of the 2nd unit antenna pattern 4 of the antenna apparatus 1 which mentioned above the basic form which connects between the 1st via hole 34 and the 2nd via hole 35 which oppose. However, the first vertical portion 33a2 and the second vertical portion 33a6 that are opposite to each other are formed on both sides, and the inclined side portion 33a4 is formed in the central portion so that one pitch region is utilized. Therefore, the pattern length of the second unit antenna pattern 33 is extended by a length corresponding to these portions as compared with the second unit antenna pattern 4 of the antenna device 1.

In the antenna device 30 configured as described above, the pitch p of the helical pattern is halved and the length of the pattern is increased. When the antenna device 30 is manufactured using a double-sided substrate 31 having a length of 30 mm and a thickness of 2 mm, the antenna device 30 exhibits input characteristics as shown in FIG. Despite being small in size, the antenna device 30 obtains an input characteristic having a VSWR of 3 or less in a frequency band of about 580 MHz to about 660 MHz as shown by a solid line in FIG. As described above, the antenna device 30 adds more folded portions to the multiple first unit antenna patterns 32, so that more currents cancel each other out and a wider band is achieved.

Further, the antenna device 30 can be further widened by connecting the matching circuit 13 described above. The matching circuit 13 has a circuit constant set by a combination of the first coil 14 having an inductance of 18 nH, the second coil 15 having an inductance of 4.7 nH, and the capacitor 16 having a capacitance of 3 pH. By connecting this matching circuit 13, the antenna device 30 can obtain an input characteristic having a VSWR of 3 or less in a frequency band of about 480 MHz to about 720 MHz as shown by a chain line in FIG. The antenna device 30 does not require a switching operation for switching circuit constants.

  Thinned antenna device 30 (thickness 2.2 mm, length 30 mm), antenna device 1A (thickness 3.2 mm, length 40 mm) and antenna device 1B (thickness 3.2 mm, length 30 mm) described above FIG. 14 shows the frequency characteristics of the antenna gain. In the figure, the solid line represents each maximum gain, and the broken line represents each average gain. The antenna device 30 has antenna characteristics equivalent to those of the antenna device 1A and the antenna device 1B even when a thin substrate is used.

  By the way, in the antenna device 1 and the antenna device 30, as described above, the reception characteristics of the VHF band as well as the UHF band are required corresponding to the new broadcasting system, and it is necessary to meet the demand for further miniaturization. In the antenna device 1 and the antenna device 30, as described above, each first unit antenna pattern 3, 32 has a folded portion that constitutes the opposite sides facing each other, thereby forming a multiple loop and storing energy therein. . In the antenna device 1 and the antenna device 30, as described with reference to FIG. 2B described above, the first magnetic field 11 and the second magnetic field 12 that are opposite in phase to each other at the folded portions 100 of the first unit antenna pattern 3. Is generated, and the accumulated energy is more dominant than the electric field energy.

  FIG. 15 is an analysis of changes in the wavelength shortening effect with respect to changes in the material constants of the relative permittivity and relative permeability of the substrate material. In the figure, the solid line shows the amount of change in the wavelength shortening effect when the magnetic material is selected and the relative permittivity is changed, and the broken line changes the relative permeability by mixing the magnetic material with the substrate material. The amount of change in the wavelength shortening effect in the case of being applied is shown.

  In the antenna device 1 and the antenna device 30, since the magnetic field energy is dominant as the energy accumulated inside as described above, the magnetic permeability change has a greater influence than the dielectric constant change of the substrate material. In the antenna device 1 and the antenna device 30, as apparent from FIG. 15, a larger wavelength shortening effect can be obtained by changing the relative permeability rather than changing the relative permittivity of the substrate material, thereby further reducing the size. Be able to. Therefore, in the antenna device 1 and the antenna device 30, the double-sided substrates 2 and 31 are formed of a substrate material obtained by mixing a magnetic material with a generally used dielectric material. For example, a hexagonal ferrite material is extremely effective because the permeability does not decrease even in the UHF band.

  As described above, the antenna device 1 and the antenna device 30 can be formed on the double-sided substrates 2 and 31 having a size of about 40 mm or 30 mm. Therefore, the antenna device 1 and the antenna device 30 may be directly formed on a part of the circuit board 40 on which various electronic components are mounted as shown in FIG. With this configuration, the antenna device 1 and the antenna device 30 can be integrated with, for example, a transmission / reception circuit unit and a control circuit unit, improving space efficiency and assembly efficiency and enabling function confirmation before mounting, etc. Make significant cost reductions. The antenna device 1 and the antenna device 30 can be mounted on a small device such as a cellular phone. Since the protrusion amount is small, the usability is improved and the design development is moderated.

  Further, the antenna device 1 and the antenna device 30 have a characteristic that the dependence on the ground is small as described above. Therefore, the antenna device 1 and the antenna device 30 can also be formed directly on a part of the housing, like a mobile phone 45 having a reception function of the new broadcasting system shown in FIG. The mobile phone 45 does not need to watch a broadcast program by pulling out a long rod antenna from the casing, and can greatly improve usability.

  In the antenna device 1 and the antenna device 30 shown as the embodiment, a unit antenna pattern is formed on the front and back main surfaces of the double-sided substrates 2 and 31, and these are interlayer-connected by via holes to form a three-dimensional helical antenna pattern. However, it is not limited to such a configuration. The present invention can be miniaturized by applying it to a so-called meander antenna having a continuous pattern having a large number of folded portions on a single-sided printed board, for example.

It is a front view of the antenna device shown as an embodiment. It is the principal part block diagram of the antenna device, the figure (A) is a longitudinal cross-sectional view, and the figure (B) is a principal part front view. The analysis result of the dependence with respect to the ground in a state where the substrate is upright in the antenna device is shown, FIG. The analysis result of the dependence with respect to a ground in the state which made the board | substrate parallel in the same antenna apparatus is shown, The figure (A) is a schematic diagram, The figure (B) is a characteristic view. It is a matching circuit diagram connected to an antenna device. It is an input characteristic figure at the time of connecting the matching circuit which made the antenna device single-piece | unit and a circuit constant different. It is a frequency characteristic figure of the antenna gain of an antenna device and the conventional antenna device. It is a radiation characteristic figure of an antenna device and the conventional antenna device. It is an analysis figure of an antenna pattern and its antenna length. It is a change characteristic figure of the helical length with respect to the helical pitch in each antenna pattern. It is a change characteristic figure of the helical length with respect to the thickness of the double-sided board in each antenna pattern. It is a figure explaining the structure of the 1st unit antenna pattern and the 2nd unit antenna pattern in the antenna apparatus shown as 2nd Embodiment, The figure (A) is a principal part front view, The figure (B) is required. FIG. It is an input characteristic figure at the time of connecting a matching circuit with the same antenna device. It is a frequency characteristic figure of the antenna gain of each antenna device. It is a change characteristic figure of the wavelength shortening effect by a material constant. It is a perspective view of the component mounting board | substrate which formed the antenna device directly. It is a perspective view of the mobile telephone which formed the antenna apparatus in the housing | casing. It is a perspective view of the conventional portable television. It is a figure explaining arrangement | positioning of a rod antenna and a ground board, The figure (A) shows the state in which the rod antenna stood upright with respect to the ground board , The figure (B) parallels the rod antenna with respect to the ground board. it is a diagram obtained by a state. It is an input characteristic diagram by arrangement of a rod antenna and a ground plate. The figure (A) shows the state where the rod antenna stands upright with respect to the ground board , and the figure (B) shows the rod antenna parallel to the ground board. It shows the state.

DESCRIPTION OF SYMBOLS 1 Antenna apparatus, 2 Double-sided board, 2a 1st main surface, 2b 2nd main surface, 3 1st unit antenna pattern, 4 2nd unit antenna pattern, 5 1st via hole, 6 2nd via hole, 7 3rd via hole, 10 Ground, 11 First magnetic field, 12 Second magnetic field, 13 Matching circuit, 20 A to 20 D antenna pattern, 30 Antenna device, 31 Double-sided board, 32 First unit antenna pattern, 33 Second unit antenna pattern, 34 First via hole, 35 Second via hole, 40 circuit board, 45 mobile phone, 100 folded part

Claims (2)

A vertically long rectangular double-sided board in which a conductive foil is provided on a first main surface and a second main surface of a substrate material obtained by mixing a magnetic material with a dielectric material;
By performing patterning processing on the conductor foil provided on the first main surface of the double-sided substrate, arranged along the length of each independently from each other in the left and right side regions sandwiching the center in the width direction on the first main surface, A vertical pattern portion that faces each other at the center of the double-sided substrate, and an upper horizontal pattern portion that is bent toward the side at the upper end of the vertical pattern portion and has a leading end located near the side edge of the double-sided substrate And a lower horizontal pattern portion that is bent in a lateral direction at a lower end of the vertical pattern portion and that is adjacent to a front end portion of the upper horizontal pattern portion that is adjacent in the length direction. Each of the pattern portions is constituted by a substantially U-shaped folded pattern having a central side opened in a region between the upper horizontal pattern portion and the lower horizontal pattern portion at a midpoint. And plurality of first unit antenna pattern consisting of pattern substantially U-shaped folded shape forming a symmetrical above the left and right side regions having an open side edge of the rear substrate and the basic form,
By performing patterning processing on the conductor foil provided on the second main surface of the double-sided substrate, respectively arranged in one another independently of the length direction, one region of the one end of the left and right side regions on the second main surface Corresponding to the upper horizontal pattern portion of the first unit antenna pattern formed on the other side and corresponding to the lower horizontal pattern portion of the first unit antenna pattern formed on the other side of the left and right side regions. A plurality of second unit antenna patterns each including a positioned pattern;
Along the side edges of the double-sided substrate , the tip of the upper horizontal pattern portion of the first unit antenna pattern facing the tip, the tip of the second unit antenna pattern, and the bottom of the first unit antenna pattern facing each other. It is formed to penetrate through the first main surface and the second main surface with a predetermined pitch in the length direction corresponding to the front end portion of the horizontal pattern portion and the other end portion of the second unit antenna pattern. each conduction process inside Rutotomoni is performed, the plurality of via holes formed by connecting between layers alternating between opposing pattern opposing the first unit antenna pattern and the second unit antenna pattern,
A power supply terminal portion formed at one end in the length direction of the double-sided substrate;
By performing patterning processing on the conductor foil provided on the first major surface or the second main surface of the double-sided substrate, one end portion and the Rutotomoni other end to connect with the power supply terminal portions to form the power supply terminal portions is composed of a feeding pattern connected to the length direction of the first unit antenna pattern is formed is positioned on one end side or the second unit antenna pattern of the double-sided substrate,
The lower side of the first unit antenna pattern formed relative to the top horizontal pattern portion of the first unit antenna pattern or the lower horizontal pattern portion of the first unit antenna pattern formed on one side of the double-sided substrate and the other region side. By connecting the tip of the horizontal pattern part or the upper horizontal pattern part to the second unit antenna pattern facing each other via the via hole, the whole is connected in series, and one end side is connected to the power supply terminal part and the like. An antenna device in which a three-dimensional helical antenna pattern having an open end is formed in the first main surface and the second main surface of the double-sided board . The double-sided board constitutes a circuit board mounting board, and the first unit antenna pattern , the second unit antenna pattern, the via hole, the feed terminal portion, and the feed pattern are formed in a partial region of the circuit board. Item 2. The antenna device according to Item 1.

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