JP2005079747A - Communication equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the communication efficiency of communication equipment and to enable comfortable communication. <P>SOLUTION: Communication equipment is provided with a ground antenna of a resonance wavelength λ, a first ground 15 for a high frequency where a length from a ground point of the ground antenna to an opening end is set to be equal to a length which is the natural-number fold of λ/4 and a digital second ground 17 which is electrically connected to the first ground 15 through a connection point 21. The connection point 21 is arranged in a position except for a position detached from the ground point along the length direction of the first ground 15 by a distance equal to a length which is the natural-number fold of λ/4. Thus, a more desirable ground state for the antenna can be provided by such a structure. Consequently, the communication efficiency of communication equipment is improved and comfortable communication is attained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a communication device incorporating an antenna.

A wireless communication unit 101 shown in FIG. 26 includes a chip antenna 103, a first ground 105 that constitutes a part of the analog circuit unit, and a second ground 109 that is separate from the first ground 105. The first ground 105 has a connection point 107 on one side thereof, and is connected to the second ground 109 by the chip inductor 111 through the connection point 107. The chip inductor 111 electrically connects the first ground 105 and the second ground 109, and has a function of separating both the grounds with high impedance in terms of high frequency. The total perimeter of the first ground 105 is configured to be close to one wavelength of the used wavelength. Since the first ground 105 is substantially square, the length of one side where the connection point 107 is present is 1 / of the used wavelength. The length is substantially equal to the length of 4 (see Document 1).
JP 2001-168625 A (see paragraphs 0066 to 0076, FIG. 5)

  However, in the method described in the above document, since both grounds are connected via a chip inductor, a larger inductor may be required depending on the operating frequency, and the grounding state due to the inductor affects the antenna performance. May also occur. Accordingly, an object of the present invention is to provide a more desirable grounding state for an antenna.

  In order to achieve the above object, the position of the connection point 107 is probably at the open end on one side of the first ground 105, so that the antenna voltage e is maximized at that point (or the antenna current i is I got the knowledge that it might be because it becomes the smallest. The present invention has been made based on this finding. It should be noted that the definitions of terms used to describe the invention according to any claim shall be applied to the invention according to other claims as long as possible in nature.

(Characteristics of the invention of claim 1)
The communication device according to the first aspect of the present invention is a high-frequency device in which a ground antenna having a resonance wavelength λ and a length from the ground point to the open end of the ground antenna are set equal to a length that is a natural number multiple of λ / 4. And a digital second ground electrically connected to the first ground via a connection point, the connection point being a natural number multiple of λ / 4 from the ground point. Are arranged at positions other than the positions separated along the length direction of the first ground by a distance equal to That is, no connection point is provided at a position separated from the grounding point by a length equal to λ / 4, 2λ / 4, 3λ / 4,... Nλ / 4. The antenna radiation efficiency can be improved by avoiding the position where the antenna voltage e is maximized (or the antenna current i is minimized).

(Characteristics of the invention described in claim 2)
A communication apparatus according to a second aspect of the present invention is the communication apparatus according to the first aspect, wherein the connection point is a distance equal to a length of a natural number multiple of λ / 8 + λ / 4 ± λ / 16 from the antenna grounding point. It is arranged within the range. As a position other than the position where the antenna voltage e becomes maximum (or where the antenna current i becomes minimum), for example, a connection point can be arranged at the above-described position.

(Characteristics of Claim 3)
A communication device according to a third aspect of the present invention is the communication device according to the first or second aspect, wherein the connection point is separated from the ground point by a distance equal to a length that is a natural number multiple of λ / 8 + λ / 4. It is placed at the position. As a position other than the position where the antenna voltage e becomes maximum (or where the antenna current i becomes minimum), for example, a connection point can be arranged at the above-described position.

(Feature of the invention of claim 4)
A communication device according to a fourth aspect of the present invention is the communication device according to any one of the first to third aspects, wherein the connection point is ± λ / 16 from the center of the length from the ground point to the open end. It is arranged within the range of length equal to the length. As a position other than the position where the antenna voltage e becomes maximum (or where the antenna current i becomes minimum), for example, a connection point can be arranged at the above-described position.

(Feature of the invention of claim 5)
A communication apparatus according to a fifth aspect of the present invention is the communication apparatus according to any one of the first to third aspects, wherein the connection point is arranged at the center of the length from the grounding point to the open end. As a position other than the position where the antenna voltage e becomes maximum (or where the antenna current i becomes minimum), for example, a connection point can be arranged at the above-described position.

(Characteristics of the invention described in claim 6)
A communication device according to a sixth aspect of the invention includes a ground antenna having a resonance wavelength λ, a high-frequency circuit connected to the ground antenna, a ground serving as the ground of the high-frequency circuit, and a pair of the ground antenna and the antenna. And a digital circuit and a digital ground provided separately from the high-frequency circuit and the high-frequency ground. The high-frequency ground and the digital ground are electrically connected via a connection point of the high-frequency ground. The high-frequency ground connection point is excluded from the sides defining the high-frequency ground except for the first side adjacent to the grounded antenna and the second side facing the first side. It is arranged on either side. As a position other than the position where the antenna voltage e becomes maximum (or where the antenna current i becomes minimum), for example, a connection point can be arranged at the above-described position.

(Feature of the invention of claim 7)
A communication device according to a seventh aspect of the present invention is the communication device according to the sixth aspect, wherein the high-frequency ground length from the ground point to the open end of the ground antenna is a length that is a natural number multiple of λ / 4. The connection points are arranged within a range equal to the length of ± λ / 16 from the center of the length from the grounding point to the open end. As a position other than the position where the antenna voltage e becomes maximum (or where the antenna current i becomes minimum), for example, a connection point can be arranged at the above-described position.

(Characteristics of the invention described in claim 8)
The communication device according to an eighth aspect of the present invention is the communication device according to the sixth aspect, wherein the connection point is arranged at the center of the length from the ground point of the ground antenna to the open end of the high-frequency ground. is there. As a position other than the position where the antenna voltage e becomes maximum (or where the antenna current i becomes minimum), for example, a connection point can be arranged at the above-described position.

  According to the present invention, it is possible to provide a more desirable grounding state for the antenna, thereby improving the communication efficiency of such a communication device and realizing comfortable communication.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic perspective view of a wireless barcode reader for reading a barcode, which is an example of a communication device. FIG. 2 is a plan view of the wireless barcode reader shown in FIG. 3 to 7 are tables showing the VSWR characteristics of the wireless communication unit shown in FIG. FIG. 8 is a plan view showing a first modification of the wireless barcode reader shown in FIG. 9 to 13 are charts showing the VSWR characteristics of the wireless communication unit shown in FIG. FIG. 14 is a plan view showing a second modification of the present embodiment. 15 to 17 are charts showing the VSWR characteristics of the wireless communication unit shown in FIG. FIG. 18 is a plan view showing a third modification of the present embodiment. 19 to 21 are tables showing the VSWR characteristics of the wireless communication unit shown in FIG. FIG. 22 is a plan view showing a fourth modification of the present embodiment. FIG. 23 is a chart showing the VSWR characteristics of the wireless communication unit shown in FIG. FIG. 24 is a plan view showing a fifth modification of the present embodiment. FIG. 25 is a chart showing the VSWR characteristics of the wireless communication unit shown in FIG. In the wireless communication unit shown in FIGS. 1 and 2, various electronic components included in the wireless communication unit are omitted in order to avoid the complexity of the drawings.

(Schematic structure of communication device)
This will be described with reference to FIGS. A wireless barcode reader 1 that functions as a communication device is a reader (scanner) that reads barcodes displayed on various products, ID cards, and the like and wirelessly transmits the read data. A main body 3, a wireless communication unit 7 for transmitting data read from a barcode provided in the reader main body 3, a light emitting / receiving unit and various electronic units (not shown) for reading data, etc. , Generally.

(Structure of wireless communication unit)
As shown in FIGS. 1 and 2, the wireless communication unit 7 includes a high-frequency circuit unit 9 and a digital circuit unit 11 that is separate from the high-frequency circuit unit 9. The high-frequency circuit unit 9 includes a chip antenna 13 placed on a printed circuit board and a high-frequency ground (first ground) 15 patterned thereon, and is configured to resonate at a resonance frequency f (resonance wavelength λ). It is. The resonance frequency f is set to, for example, 2400 to 2483.5 MHz (hereinafter referred to as “2.4 GHz band” for convenience) in order to be applicable to the communication method “Bluetooth”. It is also possible to set a frequency band other than the band (for example, a 5 GHz band for wireless LAN). The chip antenna 13 is a dielectric antenna because it is relatively advantageous for downsizing, but other types of antennas may be used. The digital circuit unit 11 includes a digital ground (second ground) 17 patterned on a printed circuit board, and the digital ground 17 is formed in a substantially rectangular shape having four sides as shown in FIGS. It does not interfere with the formation of a shape other than a rectangular shape.

(Chip antenna structure)
This will be described with reference to FIG. The chip antenna 13 is a so-called dielectric antenna, and includes a ground antenna 13a configured by applying a conductive paste to a dielectric material such as ceramic and a short line 13p for impedance matching, and is generally an inverted F type. An antenna also called an antenna. The ground antenna 13a is an inverted L-shaped element having a feeding end 13b, an open end 13d, and a bent portion 13c between the feeding end 13b and the open end 13d. The short line 13p is an inverted L-shaped linear conductor including a ground end 13q and a connection end 13s connected to the ground antenna 13a via a bent portion 13r. In this embodiment, the connection end 13s of the short wire 13p is connected to the bent portion 13c of the ground antenna 13a, that is, the connection end 13s and the bent portion 13c are made to coincide with each other. In order to adjust the impedance, it is possible to shift in the direction of the feed end 13b or the open end 13d. It is also possible to reverse the positions of the power feeding end 13b and the grounding end 13q and arrange the former on the left side and the latter on the right side in FIG. The ground antenna 13a and the short line 13p can be configured in a meander shape as necessary, or can be modified by adding a stub to the former if necessary. Furthermore, not only an inverted F-type antenna but also a monopole antenna may be employed.

(High frequency ground)
The high-frequency ground 15 is formed in a rectangle having a base 15 a (a side between the other sides 15 b and 15 c), and the base 15 a is adjacent to one side 17 a of the digital ground 17. The high-frequency ground 15 is set to be approximately equal to the length of ¼ of the operating wavelength λ in order to resonate at a desired frequency. The high-frequency ground 15 is electrically connected to the digital ground 17 via a connection point 15p included in the high-frequency ground 15 and a connection point 17p included in the digital ground 17 (see FIG. 2). The connection between the connection point 15p and the connection point 17p is made by a conductor foil 21 such as a copper foil.

  Next, the position where the connection point 15p is provided will be described. The connection point 15p is provided at substantially the center between the intersection 15q of the perpendicular line passing through the grounding end 13q of the short line 13p and the bottom side 15a of the high-frequency ground 15 and the bottom side 15a and the other side 15c. That is, since the length between the intersection 15q of the high-frequency ground 15 and the other side 15c is set to be substantially equal to ¼ of the wavelength λ used, the connection point 15p has a length of λ / 8 from the other side 15c. That is, it is arranged at a position slightly closer to the other side 15b than the position moved by a length equal to that of the other side. The first reason why the connection point 15p is arranged at such a position is that the antenna voltage is maximized, that is, the intersection 15q shown in FIG. In the point. This is because the radiation efficiency can be improved by arranging the antenna voltage at a position other than the position where the antenna voltage is maximum as compared with the case where the antenna voltage is maximized. Furthermore, according to the experiment described later, even when the voltage is disposed at a position where the maximum voltage position is removed, the best result can be obtained when it is disposed in the central region between the intersection 15q and the other side 15c. Because it was made. This is the second reason why the connection point 15p is arranged at the above position.

(Experimental result of this embodiment)
This will be described with reference to FIGS. The charts shown in FIGS. 3 to 7 show the VSWR characteristics when the connection point 15p of the high-frequency ground 15 shown in FIG. 2 is moved in the + (left direction in the figure) direction or the − (right direction in the figure) direction. Yes. Similarly, X indicates a distance in which only the connection point 15p is moved left and right without moving the high-frequency ground 15. “X = 0 mm” indicates that the connection point 15p is located at the center between the intersection 15q and the other side 15c. For example, “X = + 9 mm” indicates that the connection point 15p is in the + direction (left direction) in the figure. It shows that it has moved 9mm from the center. Note that the straight line L shown in FIG. 2 is a perpendicular to the base 15a passing through the connection point 15p. Here, the resonance frequency f is set in the 2.4 GHz band. Therefore, the length between the intersection 15q and the other side 15c is slightly smaller than 32 mm which is a length equal to ¼ of the use wavelength λ. The length was set to 36 mm. The conductive foil 21 connecting the connection point 15p of the high-frequency ground 15 and the connection point 17p of the digital ground 17 is a copper foil having a width of 3 mm and a length of 6 mm.

  As is apparent from FIGS. 3 to 7, when the VSWR characteristic is observed, it can be seen that the state shown in FIG. 5 is the best state. The state shown in the figure is “VS = 0 mm” in the range of 2.4 to 2.5 GHz when “X = 0 mm”, that is, when the connection point 15p is arranged in the center between the intersection 15q and the other side 15c. Got. On the other hand, as shown in FIGS. 4 and 6, when “X = ± 9 mm”, the value was less than VSWR2 at the center frequency of 2.45 GHz. Further, as shown in FIGS. 3 and 7, when “X = ± 18 mm”, the value was equal to or higher than VSWR2 at the center frequency of 2.45 GHz.

  From the above experiment, it was found that the VSWR characteristic when the connection point 15p is arranged at the center between the intersection 15q and the other side 15c is most preferable, and the characteristic deteriorates when the connection point 15p deviates from the center. Furthermore, from this experimental result, the relationship between the length between the intersection 15q and the other side 15c and the resonance frequency f (resonance wavelength λ) of the chip antenna 13 can be analyzed as follows. That is, in the above experiment, since the resonance frequency f is set to 2.4 GHz, the resonance wavelength is approximately 125 mm. Accordingly, 1 / 4λ is approximately 32 mm, but in this experiment, the operation of the arrangement of each component also worked, and optimization was possible by setting the distance from the grounded end of the antenna to 36 mm. Since the length of the bottom 15a of the high-frequency ground 15 shown in FIG. 2 in the direction away from the chip antenna 13 is 36 mm, the length is substantially equal to the length of 1 / 4λ. Therefore, the antenna voltage is maximized (antenna current is minimized) at the right end of the high-frequency ground 15 shown in FIG. It can be seen that a preferable VSWR characteristic can be obtained when the connection point 15p is provided at a position where the antenna voltage is removed from the base antenna 15a at the base 15a in the direction away from the chip antenna 13 shown in FIG. It was.

(First modification of this embodiment)
This will be described with reference to FIG. The wireless barcode reader 31 according to this modification differs from the wireless barcode reader 1 described above only in the shape of a digital ground (second ground). Therefore, the description of the configuration below will be made only for the digital ground, and the description of the other components will be omitted as appropriate.

  As shown in FIG. 8, the reader main body 33 included in the wireless barcode reader 31 has a wireless communication unit 37 therein. The wireless communication unit 37 includes a high-frequency circuit unit 39 and a digital circuit unit 41 that is separate from the high-frequency circuit unit 39. The high-frequency circuit unit 39 includes a chip antenna 43 placed on a printed circuit board and a high-frequency ground (first ground) 45 patterned thereon, and resonates at a resonance frequency of 2.45 GHz (resonance wavelength λ). It is configured. The digital circuit unit 41 includes a digital ground (second ground) 47 that is patterned on a printed circuit board. The digital ground 47 is different from the digital ground 17 according to the present embodiment in that it has a protrusion 47a. The protrusion 47a is formed mainly to allow various components (not shown) to be mounted on the back side of the printed circuit board having the digital ground 47 by protruding the protrusion 47a.

(Experimental result of this modification)
As is apparent from FIGS. 9 to 13, when the VSWR characteristic is observed, it can be seen that the state shown in FIG. 11 is the best state. In the state shown in the figure, when “X = 0 mm”, that is, when the connection point 45p is arranged at the center of one side 45a of the high-frequency ground 45, VSWR2 or less is obtained in the range of 2.4 to 2.5 GHz. . On the other hand, when “X = + 9 mm” shown in FIG. 10, VSWR2 or less was obtained at the center frequency of 2.45 GHz, and when “X = −9 mm” shown in FIG. 12, the center frequency was 2.45 GHz. Furthermore, as shown in FIG. 9, when “X = + 18 mm”, the value is equal to or higher than VSWR2 at the center frequency of 2.45 GHz, and when “−18 mm” as shown in FIG. A value of VSWR2 or more was shown.

  According to the above experiment, the VSWR characteristic when the connection point 45p is arranged at the center of one side 45a of the high-frequency ground 45 (the side between the other sides 45b and 45c) is most preferable. I understood. In this respect, it is the same as the wireless barcode reader 1 according to the present embodiment, but the wireless barcode reader 31 according to the present modification has a more applicable range as is apparent from the chart of FIG. I found it wide. Therefore, also in this modification, it is preferable when the connection point 45p is provided at a position where the antenna voltage is removed from the maximum length of the side 45a of the high frequency ground 45 shown in FIG. It was found that VSWR characteristics can be obtained.

(Second modification of this embodiment)
This will be described with reference to FIGS. The second modification differs from the present embodiment only in the shape of the high-frequency ground 15 shown in FIG. That is, when the high-frequency ground of the wireless communication unit 7 shown in FIG. 14 is compared with the high-frequency ground shown in FIG. 2, the triangle deletion area 15f indicated by the two-dot chain line is deleted, and the triangle having the same shape as the triangle deletion area 15f is correspondingly deleted. The difference is that an additional area 15g is added. Therefore, for the portions common to the wireless communication unit shown in FIG. 2, the same reference numerals as those used in FIG. 2 are used for the wireless communication unit shown in FIG. The same in the three variations). In the wireless communication unit 7 having the above-described shape, the angle a shown in FIG. 14 was changed and the experiment was performed under the same conditions as in the present embodiment. As a result, the VSWR characteristics shown in FIGS. That is, when the angle a was set to 15 degrees, 30 degrees, and 45 degrees, VSWR2 or less was obtained at the center frequency of 2.45 GHz.

(Third Modification of this Embodiment)
This will be described with reference to FIGS. The high-frequency ground 15 shown in FIG. 18 is different from the high-frequency ground 15 shown in FIG. 14 in that the positions of the triangular deletion area 15f and the triangular additional area 15g are upside down. When the angle a shown in FIG. 18 was changed and the experiment was performed under the same conditions as in the present embodiment, the VSWR characteristics shown in FIGS. 19 to 21 were obtained. That is, when the angle a was set to 15 degrees, 30 degrees, and 45 degrees, VSWR2 or less was obtained at the center frequency of 2.45 GHz.

(Fourth modification of the present embodiment)
This will be described with reference to FIGS. The fourth modification is a further modification of the third modification shown in FIG. The only difference between them is the shape of the high-frequency ground 15 shown in FIG. That is, the high frequency ground of the wireless communication unit 7 shown in FIG. 18 is different from the high frequency ground shown in FIG. 22 in that the rectangular deletion area 15j indicated by a two-dot chain line is deleted. The angle a is set to 45 degrees. Therefore, for the parts common to the wireless communication unit shown in FIG. 18, the same reference numerals as those used in FIG. 18 are used for the wireless communication unit shown in FIG. The same in the five variations). When the wireless communication unit 7 having the above shape was performed under the same conditions as the experiment performed in the present embodiment, the VSWR characteristics shown in FIG. 23 were obtained. That is, the bandwidth below VSWR2 is narrower than the characteristic shown in FIG. 21, but VSWR2 or below was obtained at the center frequency of 2.45 GHz.

(Fifth modification of this embodiment)
This will be described with reference to FIGS. The fifth modification is a further modification of the fourth modification shown in FIG. 22 is different from the high frequency ground 15 shown in FIG. 24 in that the rectangular deletion area 15k indicated by a two-dot chain line is deleted from the former. The angle a is set to 45 degrees. When the wireless communication unit 7 having the above shape was performed under the same conditions as the experiment performed in the present embodiment, the VSWR characteristics shown in FIG. 25 were obtained. That is, the bandwidth below VSWR2 is almost the same as the characteristic shown in FIG. 23, and VSWR2 or below was obtained at the center frequency of 2.45 GHz.

(Discussion)
If the principle of the present invention is considered based on the above experimental results, it will probably be as follows. That is, the position of the connection point 15p (see FIG. 2) in this embodiment and the connection point 45p (see FIG. 8) in this modification is an open end on one side of the high-frequency ground 15 or the high-frequency ground 45 that is the first ground. It seems that good results were obtained by placing it at a position other than the short end. At the open end, the antenna voltage becomes maximum at that point (and the current becomes maximum at the short end). It seems that avoiding this is a good result, that is, a factor for improving the radiation efficiency. Then, the connection point 15p or the connection point 45p is set to a point at which the antenna voltage becomes maximum, that is, on the first ground, from the chip antenna 13 or the intersection 15q (ground point) to 1/4 of the wavelength λ used. In order to obtain a good result, it is important not to provide it on a point separated by a distance equal to the length of a natural number multiple of the length equal to the length.

  When the above consideration is embodied, for example, a position other than a position separated from the intersection 15q by a distance equal to the length of a natural number multiple of λ / 4, a natural number multiple of λ / 8 + λ / 4 ± λ / 16 from the intersection 15q. A position within a distance equal to the length, a position separated from the intersection 15q by a distance equal to a length that is a multiple of λ / 8 + λ / 4, and a natural number of λ / 4 among the sides that define the high-frequency ground. A position on the side having a length equal to the double length, a position within a distance equal to the length of ± λ / 16 from the center between the intersection 15q and the other side 15c, and the natural of λ / 4 of the first ground Among the sides defining the high-frequency ground, the first side adjacent to the ground antenna (chip antenna) and the second opposite to the first side among the center position of the side having a length equal to several times the length The position on any side excluding the side, the intersection 15q and A connection point 15p or a connection point at a position within a distance equal to ± 1/16 of the resonance wavelength λ of the ground antenna from the center between the other sides 15c, or a center position between the intersection 15q and the other side 15c. It can be expected that the radiation efficiency is improved by providing 45p.

  2 and 8 are arranged so as to be parallel to the length direction of the high-frequency ground, but as shown in FIG. 14, they are arranged so as to be perpendicular to the length direction. Also good. Also in the case shown in FIG. 14, it is most preferable to arrange the connection point 15p at the center position between the intersection (grounding point) 15q and the other side 15c in order to improve the radiation efficiency.

  The wireless barcode reader 1 and the wireless barcode reader 31 described above are examples of the application target of the present invention, and it goes without saying that other electronic devices (communication devices) can be applied. For example, mobile phones, PDAs (Personal Digital Aids), and all those incorporating a wireless communication unit such as a personal computer are targeted.

It is a schematic perspective view of the wireless barcode reader for reading the barcode which is an example of a communication apparatus. It is a top view of the radio | wireless barcode reader shown in FIG. 3 is a chart showing VSWR characteristics of the wireless communication unit shown in FIG. 2. 3 is a chart showing VSWR characteristics of the wireless communication unit shown in FIG. 2. 3 is a chart showing VSWR characteristics of the wireless communication unit shown in FIG. 2. 3 is a chart showing VSWR characteristics of the wireless communication unit shown in FIG. 2. 3 is a chart showing VSWR characteristics of the wireless communication unit shown in FIG. 2. It is a top view which shows the 1st modification of the radio | wireless barcode reader shown in FIG. It is a graph which shows the VSWR characteristic of the radio | wireless communication unit shown in FIG. It is a graph which shows the VSWR characteristic of the radio | wireless communication unit shown in FIG. It is a graph which shows the VSWR characteristic of the radio | wireless communication unit shown in FIG. It is a graph which shows the VSWR characteristic of the radio | wireless communication unit shown in FIG. It is a graph which shows the VSWR characteristic of the radio | wireless communication unit shown in FIG. It is a top view which shows the 2nd modification of this embodiment. FIG. 15 is a chart showing VSWR characteristics of the wireless communication unit shown in FIG. 14. FIG. FIG. 15 is a chart showing VSWR characteristics of the wireless communication unit shown in FIG. 14. FIG. FIG. 15 is a chart showing VSWR characteristics of the wireless communication unit shown in FIG. 14. FIG. It is a top view which shows the 3rd modification of this embodiment. It is a graph which shows the VSWR characteristic of the radio | wireless communication unit shown in FIG. It is a graph which shows the VSWR characteristic of the radio | wireless communication unit shown in FIG. It is a graph which shows the VSWR characteristic of the radio | wireless communication unit shown in FIG. It is a top view which shows the 4th modification of this embodiment. It is a chart which shows the VSWR characteristic of the radio | wireless communication unit shown in FIG. It is a top view which shows the 5th modification of this embodiment. FIG. 25 is a chart showing VSWR characteristics of the wireless communication unit shown in FIG. 24. FIG. It is a top view of the conventional radio | wireless communication unit.

Explanation of symbols

1,31 Wireless bar code reader 3,33 Reader body 7, 37, 101 Wireless communication unit 9, 39 High frequency circuit unit 11, 41 Digital circuit unit 13, 43, 103 Chip antenna 13a Ground antenna 13b Feed end 13c Bending portion 13d Open End 13p Short line 13q Grounding end 13r Bending part 15, 45 High frequency ground (first ground)
17, 47 Digital ground (second ground)
21 Conductor foil 15p, 17p, 45p Connection point 47a Protrusion 105 First ground 109 Second ground 111 Chip inductor

Claims (8)

A grounded antenna with a resonant wavelength λ;
A high-frequency first ground in which the length from the ground point of the ground antenna to the open end is set equal to a length that is a natural number multiple of λ / 4;
A digital second ground electrically connected to the first ground via a connection point;
The connection point is arranged at a position other than the position separated from the grounding point along the length direction of the first ground by a distance equal to a length that is a natural number multiple of λ / 4. apparatus. The communication apparatus according to claim 1, wherein the connection point is arranged within a range of a distance equal to a length of a natural number multiple of λ / 8 + λ / 4 ± λ / 16 from the ground point.   3. The communication apparatus according to claim 1, wherein the connection point is arranged at a position separated from the ground point by a distance equal to a length that is a natural number multiple of λ / 8 + λ / 4. The said connection point is distribute | arranged in the range of the length equal to the length of +/- λ / 16 from the center of the length from the said earthing | grounding point to the said open end. The Claim 1 thru | or 3 characterized by the above-mentioned. Communication equipment. The communication device according to any one of claims 1 to 3, wherein the connection point is arranged at a center of a length from the ground point to the open end. A grounded antenna with a resonant wavelength λ;
A high-frequency circuit connected to the ground antenna;
A high-frequency ground that functions as a ground of the high-frequency circuit and forms a pair with the ground antenna;
A digital circuit and a digital ground provided separately from the high-frequency circuit and the high-frequency ground,
The high frequency ground and the digital ground are electrically connected via a connection point of the high frequency ground,
The connection point of the high-frequency ground is on any side of the sides that define the high-frequency ground, excluding the first side adjacent to the ground antenna and the second side facing the first side. A communication device characterized by being arranged in The high-frequency ground length from the ground point of the ground antenna to the open end is set equal to a natural number times λ / 4,
The communication device according to claim 6, wherein the connection point is arranged within a range equal to a length of ± λ / 16 from a center of a length from the ground point to the open end. The communication device according to claim 6, wherein the connection point is arranged at a center of a length from a ground point of the ground antenna to an open end of the high-frequency ground.

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