JP2013197852A - Case for portable radio terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a case for a portable radio terminal that has simple structure and can be used as an antenna not only for the UHF band, but also for the VHF band.SOLUTION: A case includes a case body 2 which is formed large enough to house a portable radio terminal, a conductive coupling sheet metal 3 which is provided in an insertion state to the case body 2, and a conductive ground expansion sheet metal 5 which is electrically connected to the conductive coupling sheet metal 3 through a connection portion 4. The conductive coupling sheet metal 3 is capacitively coupled to a circuit board 102 of the portable radio terminal 100, and the conductive ground expansion sheet metal 5 is electrically connected to the conductive coupling sheet metal 3 through the connection portion 4 so as to expand the ground of the circuit board 102 of the portable radio terminal 100. The antenna gain of the portable radio terminal 100 is improved, and not only terrestrial digital broadcasts of the low band of UHF, but also multimedia broadcasts of the VHF band can be received with high sensitivity. Further, simple structure is actualized and the cost is reducible.

Description

  The present invention relates to a case for a portable wireless terminal suitable for use in a portable wireless terminal such as a mobile phone or a smartphone capable of receiving VHF / UHF band multimedia broadcast or terrestrial digital broadcast.

  Analog TV broadcasting ended in mid-2011, and from around April 2012, multimedia broadcasting started using some of the VHF band frequencies (207.5 MHz to 222 MHz) used in analog TV broadcasting. Is done. The VHF band has a very low frequency compared to the frequency band (800 MHz to 2 GHz) used in the cellular antenna, and the size of the portable wireless terminal is about 0.1λ compared to the wavelength, making it an electrically small antenna. turn into. If it becomes an electrically small antenna, it becomes very difficult to secure the antenna performance of the VHF band in the portable radio terminal.

  For example, Patent Documents 1 and 2 disclose techniques for improving antenna performance. A grounding extension structure for coupling to a grounding means of an antenna system described in Patent Document 1, an antenna system, and a mobile communication device having the grounding structure have a grounding means that can be extended, and this grounding means is extended. Gain and SAR (Specific Absorption Rate) are improved. A portable communication terminal and a portable communication terminal case described in Patent Document 2 include a case that slidably accommodates a mobile phone to which an antenna is attached, and a protrusion that makes the mobile phone and the case relatively slidable In addition, the ground portion of the antenna and the ground connection portion that conducts to the ground portion are provided in the sliding direction on the rail portion, and the ground length of the antenna can be expanded and contracted by sliding the mobile phone and the case. It is configured.

Japanese translation of PCT publication No. 2002-512463 JP 2003-179664 A

However, the grounding extension structure for coupling to the grounding means of the antenna system described in Patent Document 1 requires an extended ground having a quarter wavelength or more, and is therefore suitable for the structure of a VHF / UHF band antenna. Absent.
The mobile communication terminal and the mobile communication terminal case described in Patent Document 2 require a slide mechanism that brings the mobile communication terminal and the case into contact with each other, which makes the structure complicated and increases the cost.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a case for a portable wireless terminal that can be used as an antenna of not only the UHF band but also the VHF band with a simple structure.

  The portable wireless terminal case according to the present invention is disposed at the upper end of the casing, a circuit board provided in the casing, having a ground, and a predetermined distance from the circuit board. A portable wireless terminal case mounted on a portable wireless terminal having an antenna element, wherein the case body, a conductive coupling sheet provided in an inserted state on the case body, and the conductive coupling sheet metal A conductive grounding sheet metal electrically connected via a portion, and when mounted on the portable wireless terminal, the conductive coupling sheet metal is disposed substantially parallel to the circuit board. Thus, the circuit board and capacitive coupling are formed, and the conductive ground enlarged sheet metal is arranged to extend downward from the lower end of the housing.

  According to the above configuration, the conductive coupling sheet metal is capacitively coupled to the circuit board of the portable wireless terminal, and the conductive ground enlarged sheet metal is electrically connected to the conductive coupling sheet metal, so that the ground of the circuit board of the portable wireless terminal is connected. Since it has been expanded, it is possible to improve the antenna gain at a frequency that can be used by the portable radio terminal. In addition, since a simple structure is sufficient, the cost can be reduced.

  In the above configuration, the conductive ground enlarged sheet metal has an electrical length of approximately 0.02λ or more in the VHF band or the UHF band.

  According to the above configuration, antenna gain can be ensured in the VHF band or the UHF band.

  In the above configuration, the connection portion between the conductive coupling sheet metal and the conductive ground expansion sheet metal is provided at one end in the width direction of the conductive coupling sheet metal or the conductive ground expansion sheet metal. .

  According to the above configuration, when an antenna is arranged at the lower end of the portable wireless terminal, the conductive coupling sheet metal and the conductive ground expansion sheet metal can be connected without considering the arrangement of the antenna.

  The said structure WHEREIN: The said electroconductive ground enlarged sheet metal was multi-stage comprised with the several slide plate, It is characterized by the above-mentioned.

  According to the above configuration, the storage property can be improved.

  In the above configuration, at least a part of the conductive coupling sheet metal overlaps the circuit board.

  According to the above configuration, although the capacitive coupling with the circuit board of the portable wireless terminal is slightly weakened, the size and weight can be reduced.

  In the above configuration, the conductive ground enlarged sheet metal has a meander shape, a loop shape, a tapered shape, or an elliptical shape.

  According to the above configuration, the size and weight can be reduced without reducing the antenna gain.

  In the above configuration, a conductive member that further extends the electrical length of the conductive ground enlarged sheet metal can be connected to the conductive ground enlarged sheet metal.

  According to the above configuration, the antenna gain can be further improved.

  In the above configuration, the conductive coupling sheet metal is capacitively coupled to the circuit board from the side surface side of the housing.

  According to the above configuration, although the capacitive coupling is slightly weakened, the effect of improving the antenna gain can be obtained.

  In the above configuration, the conductive ground enlarged sheet metal can be folded.

  According to the said structure, it is not bulky and it becomes easy to wait.

  According to the present invention, it can be used as an antenna of not only the UHF band but also the VHF band with a simple structure.

The perspective view which shows the external appearance of the state with which the case for portable radio | wireless terminals which concerns on one embodiment of this invention was mounted | worn with the portable radio | wireless terminal The figure which shows the time of portable wireless terminal mounting | wearing of the case for portable wireless terminals of FIG. The figure which shows a state when a conductive ground expansion sheet metal is folded in the case for portable wireless terminals of FIG. The figure which shows the basic composition of the 1st application example of the case for portable wireless terminals of FIG. The figure which shows the basic composition of the 2nd application example of the case for portable wireless terminals of FIG. The figure which shows the basic composition of the 2nd application example of the case for portable wireless terminals of FIG. The figure which shows the basic composition of the 3rd application example of the case for portable wireless terminals of FIG. The figure which shows the basic composition of the 4th application example of the case for portable wireless terminals of FIG. The figure which shows the basic composition of the 5th application example of the case for portable wireless terminals of FIG. The figure which shows the basic composition of the 6th application example of the case for portable radio | wireless terminals of FIG. The figure which shows the basic composition of the 7th application example of the case for portable wireless terminals of FIG. The figure which shows the basic composition of the 8th application example of the case for portable wireless terminals of FIG. The figure which shows the basic composition of the 9th application example of the case for portable wireless terminals of FIG. The figure which shows the basic composition of the 10th application example of the case for portable wireless terminals of FIG. The figure which shows the basic composition of the 11th application example of the case for portable wireless terminals of FIG. The figure for showing the basic composition of the 1st example of application of the case for portable radio terminals of Drawing 1, and explaining a simulation result The graph which shows the grand expansion length-gain improvement amount in the 1st application example of FIG. The graph which shows the frequency-gain improvement amount in the 1st application example of FIG. The figure for showing the basic composition of the 1st example of application of the case for portable radio terminals of Drawing 1, and explaining a simulation result The graph which shows the coupling capacity-gain improvement amount in the 1st application example of FIG. The figure which shows antenna current distribution when not mounting | wearing with the portable wireless terminal case of the portable wireless terminal of FIG. 1, and when mounting | wearing

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments for carrying out the invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view showing an overview of a state where a portable wireless terminal case according to an embodiment of the present invention is mounted on a portable wireless terminal. FIG. 1 (a) is an enlarged view of a conductive ground expansion sheet metal of the case. The state is shown, and (b) shows a state before closing the conductive ground enlarged sheet metal of the case. 2A and 2B show a basic configuration of a case for a portable wireless terminal according to the present embodiment, where FIG. 2A is a front view when the portable wireless terminal is attached, and FIG. 2B is a state when the portable wireless terminal is not attached. Front view, (c) is a side view when mounted on a portable wireless terminal.

  1 and 2, the portable wireless terminal 100 includes a housing 101, a circuit board 102 provided in the housing 101, having a ground, and a predetermined distance from the circuit board 102. And an antenna element 103 disposed at the upper end. The portable wireless terminal 100 can receive VHF band and UHF band multimedia broadcasts and terrestrial digital broadcasts. An antenna element 103 is used to receive multimedia broadcasts and terrestrial digital broadcasts.

  A portable wireless terminal case 1 according to the present embodiment is used by being attached to a portable wireless terminal 100, and includes a case main body 2 formed in a size that can accommodate the portable wireless terminal 100, and a case main body 2. The conductive coupling sheet metal 3 provided in the insert state, and the conductive ground expansion sheet metal 5 electrically connected to the conductive coupling sheet metal 3 via the connection portion 4 are provided. The conductive bonding sheet metal 3 is formed in a square shape. The conductive coupling sheet metal 3 is formed to be slightly smaller than the portable wireless terminal 100 and may be, for example, the same size (area) as the circuit board 102 of the portable wireless terminal 100. The conductive ground enlarged sheet metal 5 is formed in a square shape and has an electrical length of approximately 0.1λ or more in the VHF band.

  The connection portion 4 is formed of a rectangular flexible substrate, and connects the lower end center portion of the conductive coupling sheet metal 3 and the upper end center portion of the conductive ground expansion sheet metal 5. The flexible substrate is a film-like insulator (base film) having a thickness of several tens of μm and a conductor stay having a thickness of several tens of μm formed through an adhesive layer. Since the connection part 4 supports the conductive ground enlarged sheet metal 5 so as to be swingable in the vertical direction, the conductive ground enlarged sheet metal 5 can be folded.

  FIG. 3 shows a state when the conductive ground enlarged sheet metal 5 is folded, (a) is a front view when the portable wireless terminal is mounted, and (b) is a side view when the portable wireless terminal is mounted. By making the conductive ground enlarged sheet metal 5 foldable, it is not bulky and can be easily carried.

  In the portable wireless terminal case 1 according to the present embodiment, the conductive coupling sheet metal 3 is substantially parallel to the circuit board 102 of the portable wireless terminal 100 when the portable wireless terminal case 1 is attached to the portable wireless terminal 100. It arrange | positions in the case main body 2 so that it may become. The conductive coupling sheet metal 3 is used for capacitively coupling with the circuit board 102 and expanding the ground on the side far from the antenna element 103 of the portable wireless terminal 100 with the conductive ground expansion sheet metal 5. By being arranged substantially parallel to the circuit board 102 of the portable wireless terminal 100, the circuit board 102 is strongly capacitively coupled. The conductive ground enlarged sheet metal 5 is disposed so as to extend downward from the lower end of the casing 101 of the mobile wireless terminal 100 and acts as a ground for the circuit board 102. The conductive ground expansion sheet metal 5 can improve the antenna gain, and can receive not only UHF low-band terrestrial digital broadcasting but also multimedia broadcasting in the VHF band with high sensitivity.

  As described above, the conductive ground expansion sheet metal 5 also functions as a lid of the case body 2, and thus the surface side of the portable wireless terminal 100 is protected by tilting the conductive ground expansion sheet metal 5 toward the case body 2. be able to. Further, a locking portion 5a for locking to the upper end portion of the case body 2 is formed at the tip end portion of the conductive ground expansion sheet metal 5, and the case is formed by tilting the conductive ground expansion sheet metal 5 toward the case body 2 side. It is locked to the upper end of the main body 2 and does not come off easily.

  As described above, the portable wireless terminal case 1 according to the present embodiment includes a case body 2 formed to have a size capable of accommodating the portable wireless terminal 100, and a conductive coupling sheet metal 3 provided in the case body 2 in an inserted state. And a conductive ground expansion metal plate 5 electrically connected to the conductive coupling metal plate 3 via the connection portion 4, and the conductive coupling metal plate 3 is capacitively coupled to the circuit board 102 of the portable wireless terminal 100. At the same time, the conductive ground expansion sheet metal 5 is electrically connected to the conductive coupling sheet metal 3 via the connection portion 4 so that the ground of the circuit board 102 of the portable wireless terminal 100 is expanded. Antenna gain can be improved, and not only UHF low-band digital terrestrial broadcasting but also multimedia broadcasting in the VHF band can be received with high sensitivity. In addition, since the structure is simpler than those requiring a slide mechanism for bringing the mobile communication terminal into contact with the case, such as the mobile communication terminal and the mobile communication terminal case described in Patent Document 2, the cost can be reduced. I can plan.

  In addition, in the case 1 for portable wireless terminals which concerns on this Embodiment, although the electroconductive ground expansion metal plate 5 was made foldable, it does not necessarily need to be made foldable.

  Moreover, in the case 1 for portable wireless terminals which concerns on this Embodiment, the conductive ground enlarged sheet metal 5 is made into a square plate shape, and the connection part 4 is connected by the center part of the conductive coupling sheet metal 3 and the conductive ground enlarged sheet metal 5. In addition, the conductive coupling sheet metal 3 is separated from the portable wireless terminal 100 by the thickness of the case body 2, but is not limited thereto, and various modes are conceivable. Below, the application example of the case 1 for portable wireless terminals which concerns on this Embodiment is described.

(First application example)
4A and 4B show a basic configuration of a first application example of the portable wireless terminal case 1 according to the present embodiment, where FIG. 4A is a front view when the portable wireless terminal 100 is mounted, and FIG. 4B is a portable wireless terminal. 3 is a side view when the terminal 100 is mounted. FIG. As shown in the figure, in the first application example, the cellular antenna 104 disposed at the lower end of the portable wireless terminal 100 is taken into consideration, and the connection portion 4B between the conductive coupling sheet metal 3 and the conductive ground expansion sheet metal 5 is carried. The wireless terminal 100 is connected at one end in the width direction (left end as viewed in the drawing).

(Second application example)
5A and 5B show a basic configuration of a second application example of the case 1 for the portable wireless terminal according to the present embodiment. FIG. 5A is a front view when the portable wireless terminal 100 is attached, and FIG. 3 is a side view when the terminal 100 is mounted. FIG. As shown in the figure, the second application example includes a conductive ground enlarged sheet metal 5B which is configured in a multistage manner with a plurality of slide plates and which can be expanded and contracted. FIG. 5 is a basic configuration diagram illustrating a state during expansion and contraction, and FIG. 6 is a basic configuration diagram illustrating a state during expansion. As in the case of FIG. 5, FIG. 6A is a front view when attached to the portable wireless terminal 100, and FIG. 6B is a side view when attached to the portable wireless terminal 100. By adopting such a configuration, the conductive ground expansion sheet metal 5B is contracted, so that the storage property is improved and the carrying becomes easy.

(Third application example)
FIG. 7 shows a basic configuration of the third application example of the portable wireless terminal case 1 according to the present embodiment. FIG. 7A is a front view when the portable wireless terminal 100 is mounted, and FIG. 3 is a side view when the terminal 100 is mounted. FIG. As shown in the figure, the third application example is such that the conductive coupling sheet metal 3 is exposed from the surface of the case body 2 and is in close contact with the back surface of the portable wireless terminal 100 so that the conductive coupling sheet metal 3 and the circuit are connected. The distance between the substrate 102 is shortened. By adopting such a configuration, the coupling between the conductive coupling sheet metal 3 and the circuit board 102 becomes stronger, and more current can flow through the conductive ground expansion sheet metal 5.

(Fourth application example)
FIG. 8 shows a basic configuration of a fourth application example of the portable wireless terminal case 1 according to the present embodiment. FIG. 8A is a side view when the portable wireless terminal 100 is mounted, and FIG. FIG. 3 is a front view of a coupling sheet metal 3B, a connection portion 4B, and a conductive ground enlarged sheet metal 5. As shown in the figure, the fourth application example is smaller than the conductive coupling sheet metal 3 included in the portable wireless terminal case 1 and the first to third application examples according to the present embodiment described above. It has the conductive bonding sheet metal 3B. The case body 2B is also downsized in accordance with the conductive coupling sheet metal 3B. By adopting such a configuration, the connection with the circuit board 102 is slightly weakened, but the size and weight can be reduced.

(Fifth application example)
FIG. 9 shows a basic configuration of a fifth application example of the portable wireless terminal case 1 according to the present embodiment. FIG. 9A is a front view when the portable wireless terminal 100 is attached, and FIG. 3 is a side view when the terminal 100 is mounted. FIG. As shown in the figure, the fifth application example has a meander-shaped conductive ground enlarged sheet metal 5C. By adopting such a configuration, the size and weight can be reduced.

(Sixth application example)
FIG. 10 shows a basic configuration of a sixth application example of the portable wireless terminal case 1 according to the present embodiment. FIG. 10A is a front view when the portable wireless terminal 100 is attached, and FIG. 3 is a side view when the terminal 100 is mounted. FIG. As shown in the drawing, the sixth application example has a square loop-shaped conductive ground enlarged sheet metal 5D. By adopting such a configuration, it is possible to reduce the size and weight as in the fifth application example described above.

(Seventh application example)
FIG. 11 shows a basic configuration of a seventh application example of the portable wireless terminal case 1 according to the present embodiment. FIG. 11A is a front view when the portable wireless terminal 100 is mounted, and FIG. 3 is a side view when the terminal 100 is mounted. FIG. As shown in the figure, the seventh application example has a tapered conductive ground enlarged sheet metal 5E whose lower end side is widened. By adopting such a configuration, the weight can be reduced.

(Eighth application example)
FIG. 12 shows a basic configuration of the eighth application example of the portable wireless terminal case 1 according to the present embodiment. FIG. 12A is a front view when the portable wireless terminal 100 is mounted, and FIG. 3 is a side view when the terminal 100 is mounted. FIG. As shown in the figure, the eighth application example has an elliptical conductive ground metal sheet 5F. By adopting such a configuration, the weight can be reduced as in the seventh application example described above.

(Ninth application example)
FIG. 13 shows a basic configuration of a ninth application example of the portable wireless terminal case 1 according to the present embodiment. FIG. 13A is a front view when the portable wireless terminal 100 is attached, and FIG. 3 is a side view when the terminal 100 is mounted. FIG. As shown in the figure, the ninth application example has a conductive ground enlarged sheet metal 5G to which a strap 10 made of a conductive material is connected. In this case, the string-like strap 10 is connected to one side of the lower end of the conductive ground enlarged sheet metal 5G. By adopting such a configuration, the gain can be further improved.

(Tenth application example)
FIG. 14 shows a basic configuration of a tenth application example of the case 1 for a portable wireless terminal according to the present embodiment. FIG. 14A is a front view when the portable wireless terminal 100 is attached, and FIG. 3 is a side view when the terminal 100 is mounted. FIG. As shown in the figure, the tenth application example has a conductive ground enlarged sheet metal 5H to which a loop-shaped strap 11 made of a conductive material is connected. In this case, the loop-shaped strap 11 is connected to the left and right sides of the lower end of the conductive ground enlarged sheet metal 5H. By adopting such a configuration, the gain can be further improved as in the ninth application example described above.

(Eleventh application example)
FIG. 15 shows a basic configuration of an eleventh application example of the portable wireless terminal case 1 according to the present embodiment. FIG. 15A is a front view when the portable wireless terminal 100 is attached, and FIG. FIG. 4C is a front view when not attached to the end, and FIG. 5C is a side view when attached to the portable wireless terminal 100. As shown in the figure, the eleventh application example has a U-shaped conductive coupling sheet metal 3 </ b> C that is coupled to the circuit board 102 on both side surfaces of the portable wireless terminal 100. By adopting such a configuration, although the coupling with the circuit board 102 is slightly weakened, an effect of improving the gain can be obtained. Moreover, weight reduction can be achieved rather than the electroconductive coupling sheet metal 3 and 3C mentioned above.

  Next, a simulation result of the portable wireless terminal case 1 according to the present embodiment will be described. Here, a first application example of the case 1 for a portable wireless terminal will be described as an example. 16A and 16B show the basic configuration of the first application example. FIG. 16A is a front view when the mobile radio terminal 100 is mounted, and FIG. 16B is a side view when the mobile radio terminal 100 is mounted.

  FIG. 17 shows that the frequency f = 200 MHz band, the length of the circuit board 102 in the longitudinal direction (that is, the length direction of the conductive ground enlarged sheet metal 5) is 100 mm in the configuration of FIG. It is a graph which shows the amount of ground expansion length-gain improvement when changing the length (it is called "grand expansion length") of a longitudinal direction. The horizontal axis represents the ground expansion length (mm), and the vertical axis represents the gain improvement amount (dB). As shown in the figure, when the portable wireless terminal case 1 is attached to the portable wireless terminal 100 and the ground is expanded, the gain improvement amount increases as the ground expansion length increases. For example, when the ground expansion length is 30 mm (0.02λ), the gain improvement amount is 1 dB. When the ground expansion length is 65 mm (0.04λ), the gain improvement amount is 2 dB and the ground expansion length is 105 mm (0.07λ). In this case, the gain improvement amount is 3 dB, and when the ground expansion length is 145 (0.1λ) mm, the gain improvement amount is 4 dB.

  FIG. 18 is a graph showing the frequency-gain improvement amount when the ground expansion length is 100 mm (fixed), where the horizontal axis represents frequency (MHz) and the vertical axis represents gain improvement amount (dB). As shown in the figure, when the portable wireless terminal case 1 is attached to the portable wireless terminal 100 and the ground is expanded, the gain improvement effect in the VHF band and the UHF low band is increased. For example, when the frequency is 200 MHz, the gain improvement amount is 3.3 dB, when the frequency is 470 MHz, the gain improvement amount is 1.3 dB, and when the frequency is 707 MHz, the gain improvement amount is 0.4 dB.

  19A and 19B show a basic configuration of the first application example. FIG. 19A is a side view when the mobile wireless terminal 100 is mounted, and FIG. 19B is a front view when the mobile wireless terminal is not mounted. (C) is a side view when the area of the conductive bonding sheet metal 3 is reduced in (a), and (d) is a front view when the area of the conductive bonding sheet metal 3 is reduced in (b). As shown in FIG. 19E, the gap (gap) between the surface of the conductive coupling sheet metal 3 facing the portable wireless terminal 100 and the surface of the circuit board 102 on the conductive coupling sheet metal 3 side is set to 2 mm. . In this case, the thickness t1 of the casing of the portable wireless terminal 100 is 0.8 mm, and the distance t2 between the surface of the conductive coupling sheet metal 3 facing the portable wireless terminal 100 and the portable wireless terminal 100 is 1.2 mm. In addition, the relative permittivity εr of the air layer is 1.0, and the relative permittivity εr of the casing material of the portable wireless terminal 100 is 4.3. When the capacitance of the casing material of the portable wireless terminal 100 is C1, and the capacitance in the air layer is C2, the combined capacitance C can be obtained from the equation (C1 × C2) / (C1 + C2).

  FIG. 20 is a graph showing the coupling capacitance-gain improvement amount under the above conditions, where the horizontal axis represents the coupling capacitance (pF) and the vertical axis represents the gain improvement amount (dB). When the area of the conductive coupling sheet metal 3 is changed to change the coupling capacitance, the characteristics shown in FIG. 20 are obtained, and a gain improvement effect is increased by securing about C = 10 pF or more.

  FIG. 21 shows antenna current distribution when the portable wireless terminal case 1 is not attached to the portable wireless terminal 100 and when it is attached, (a) is a distribution diagram when not attached, and (b) is a distribution diagram. It is a distribution map at the time of mounting | wearing. In the figure, reference numeral 20 denotes a curve indicating the current intensity when not attached, and reference numeral 21 denotes a curve indicating the current intensity when attached. The unit of current intensity is A / m. By mounting the portable radio terminal case 1, the antenna current flows through the conductive ground enlarged sheet metal 5, and the length of the antenna element 103 is increased, thereby improving the antenna gain.

  The present invention has a simple structure and has an effect that it can be used as an antenna of not only the UHF band but also the VHF band, and can be applied to portable wireless terminals such as a mobile phone and a smartphone.

DESCRIPTION OF SYMBOLS 1 Case for portable wireless terminals 2 Case main body 3, 3B, 3C Conductive coupling sheet metal 4, 4B Connection part 5, 5B, 5C, 5D, 5E, 5F, 5G, 5H Conductive ground expansion sheet metal 10, 11 Strap 100 Portable wireless Terminal 101 Case 102 Circuit board 103 Antenna element 104 Cellular antenna

Claims (9)

A portable radio terminal having a casing, a circuit board provided in the casing and having a ground, and an antenna element disposed at an upper end of the casing at a predetermined distance from the circuit board A case for a portable wireless terminal attached to
The case body,
A conductive bonding sheet metal provided in an insert state in the case body;
A conductive ground expansion sheet metal electrically connected to the conductive coupling sheet metal through a connection portion;
When attached to the portable wireless terminal,
The conductive coupling sheet metal is arranged substantially in parallel with the circuit board to constitute capacitive coupling with the circuit board,
The case for a portable wireless terminal, wherein the conductive ground enlarged sheet metal is disposed to extend downward from a lower end of the housing.   2. The portable radio terminal case according to claim 1, wherein the conductive ground enlarged sheet metal has an electrical length of approximately 0.02λ or more in a VHF band or a UHF band.   The connection portion between the conductive coupling sheet metal and the conductive ground expansion sheet metal is provided at one end in the width direction of the conductive coupling sheet metal or the conductive ground expansion sheet metal. The case for portable wireless terminals according to claim 2.   The case for a portable wireless terminal according to any one of claims 1 to 3, wherein the conductive ground expansion sheet metal is configured in a multistage manner with a plurality of slide plates.   The case for portable wireless terminals according to any one of claims 1 to 4, wherein at least a part of the conductive coupling sheet metal overlaps the circuit board.   The portable radio terminal case according to any one of claims 1 to 5, wherein the conductive ground enlarged sheet metal has a meander shape, a loop shape, a tapered shape, or an elliptical shape.   The portable radio according to any one of claims 1 to 6, wherein a conductive member that further extends an electrical length of the conductive ground expansion sheet metal is connectable to the conductive ground expansion sheet metal. Case for terminal.   The case for portable wireless terminals according to any one of claims 1 to 7, wherein the conductive coupling sheet metal is configured to be capacitively coupled to the circuit board from a side surface of the housing.   The portable radio terminal case according to any one of claims 1 to 8, wherein the conductive ground enlarged sheet metal is foldable.