Abstract:
A radio device including: a housing, a heat sink provided on an external surface of the housing, the heat sink extending in a vertical direction of the housing, a board accommodated inside the housing in the vertical direction, the board being coupled to the heat sink through the housing, the board including a first area and a second area, the first area being located above the second area in the vertical direction, and a plurality of electronic components provided on the board, the plurality of electronic components including at least one first electronic component and at least one second electronic component, the at least one first electronic component being more heat-resistant than the at least one second electronic component, the at least one first electronic component being provided on the first area, the at least one second electronic component being provided on the second area.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2014-264953, filed on Dec. 26, 2014, the entire contents of which are incorporated herein by reference. 
       FIELD 
       [0002]    The exemplary embodiments discussed herein are related to a radio device. 
       BACKGROUND 
       [0003]    There are radio devices that includes a housing, electronic components that are accommodated in the housing, and a radiation member that is provided on an external surface of the housing and that radiates heat, which has been generated by the electronic components, to the outside of the housing (see Japanese Laid-open Patent Publication No. 2008-112870, Japanese Laid-open Patent Publication No. 2011-181880, and Japanese Laid-open Patent Publication No. 2011-155049, for example). 
       SUMMARY 
       [0004]    According to an aspect of the invention, a radio device includes a housing, a heat sink provided on an external surface of the housing, the heat sink extending in a vertical direction of the housing, a board accommodated inside the housing in the vertical direction, the board being coupled to the heat sink through the housing, the board including a first area and a second area, the first area being located above the second area in the vertical direction, and a plurality of electronic components provided on the board, the plurality of electronic components including at least one first electronic component and at least one second electronic component, the at least one first electronic component being more heat-resistant than the at least one second electronic component, the at least one first electronic component being provided on the first area of the board, the at least one second electronic component being provided on the second area of the board. 
         [0005]    The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. 
         [0006]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0007]      FIG. 1  is a perspective view illustrating a radio device according to a first exemplary embodiment; 
           [0008]      FIG. 2  is an exploded perspective view of the radio device illustrated in  FIG. 1 ; 
           [0009]      FIG. 3  is a longitudinal section of the radio device illustrated in  FIG. 1 ; 
           [0010]      FIG. 4  is a block diagram illustrating a function of the radio device illustrated in  FIG. 1 ; 
           [0011]      FIG. 5  is a front view of a board illustrated in  FIG. 2  viewed from a body case side; 
           [0012]      FIG. 6  is a partially enlarged view of  FIG. 5 ; 
           [0013]      FIG. 7  is a front view of a board of an electronic device according to a comparative example corresponding to  FIG. 4 ; 
           [0014]      FIG. 8  is a temperature distribution of the board illustrated in  FIG. 4  obtained through simulation; 
           [0015]      FIG. 9  is a temperature distribution of the board illustrated in  FIG. 7  obtained through simulation; and 
           [0016]      FIG. 10  is a longitudinal section of a radio device according to a second exemplary embodiment. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0017]    The above type of radio device has room to further improve its efficiency of radiation of heat, which the electronic components have generated, to the outside of the housing. 
         [0018]    An object of the technique disclosed in the present application is, in one aspect, to increase the efficiency of radiation of heat, which an electronic component has generated, to the outside of the housing. 
         [0019]    A first exemplary embodiment of the technology disclosed in the present application will be described first. 
         [0020]    As illustrated in  FIG. 1 , a radio device  10  according to the present exemplary embodiment is an optical extension device (a wireless unit) such as a remote radio head (RRH) or a piece of remote radio equipment (RRE) that constitutes a portion of a radio base station of a portable terminal or the like. A radio control device (a radio control unit) such as a base band unit (BBU, not shown) is connected to the radio device  10  through an optical cable  42  described later. Furthermore, an antenna  58  is connected to the radio device  10 . 
         [0021]    Furthermore, as well as converting a baseband signal (a digital signal), which has been input from the radio control device through the optical cable  42 , to a radio signal (an RF signal or an analog signal) and outputting the radio signal to the antenna  58 , the radio device  10  converts a radio signal received through the antenna  58  to a baseband signal and outputs the baseband signal to the radio control device through the optical cable  42 , for example. Hereinafter, a configuration of the radio device  10  will be described in detail. 
         [0022]    As illustrated in  FIG. 2 , the radio device  10  includes a housing  12 , a board  22 , a power source board  24 , a shield cover  26 , and an indicator  36 . Note that arrow UP illustrated in each drawing as appropriate indicates the upper side in the height direction (in the up-down direction) of the radio device  10  (the housing  12 ). Furthermore, arrow D indicates the depth direction of the radio device  10  (the housing  12 ). Furthermore, arrow W indicates the width direction of the radio device  10  (the housing  12 ). 
         [0023]    In a broad way, the housing  12  is formed in a rectangular parallelepiped shape in which the longitudinal direction is the height direction (the arrow UP direction). The housing  12  includes a body case  14  and a cover case  16  that are separated in the depth direction (the arrow D direction). The cover case  16  is formed of, for example, resin or the like. The cover case  16  is formed in a box shape having an opening on the body case  14  side. 
         [0024]    Meanwhile, the body case  14  is formed of metal or the like that is thermally conductive. The body case  14  is formed in a tabular shape that closes the opening of the cover case  16 . The cover case  16  and the body case  14  are joined to each other with screws  18 . Furthermore, the cover case  16  and the body case  14  are hermetically sealed through a waterproofing seal material or the like. 
         [0025]    A radiation member  20  that extends in the height direction of the housing  12  is provided on an external surface  14 A of the body case  14  that is on the other side with respect to the cover case  16 . The radiation member  20  includes a plurality of radiation fins  22 F that increase the surface area of the radiation member  20 . The plurality of radiation fins  22 F are formed on the external surface  14 A of the body case  14  in a rib-shape extending in the height direction of the housing  12  and are also formed so as to be integral with the housing  12  across the lower end side of the housing  12  in the height direction and the upper end side thereof. Furthermore, the plurality of radiation fins  22 F are disposed so as to be spaced apart in the width direction of the housing  12 . 
         [0026]    The board  22  is attached on an internal surface of the body case  14  on the cover case  16  side. The board  22  is a control board (a main board) on which a CPU, a memory, a plurality of electronic components  60 A (see  FIG. 4 ) described later, and the like are mounted. The board  22  is formed in a rectangular tabular shape in which the longitudinal direction is the height direction of the housing  12  and is disposed so as to extend in the height direction of the housing  12 . 
         [0027]    As illustrated in  FIG. 3 , the board  22  is fixed to the body case  14  with screws (not shown) or the like while opposing the internal surface of the body case  14 . Furthermore, the board  22  is connected to the radiation member  20  through the body case  14  so as to be capable of exchanging heat. With the above, the heat generated by the electronic components  60 A and the like that are mounted on the board  22  is released (radiated) to the outside of the housing  12  from the radiation member  20  through the board  22  and the body case  14 . 
         [0028]    The power source board  24  is attached to a lower portion of the board  22 . The power source board  24  is a control board that controls electric power supplied from a power source (not shown). The power source board  24  is disposed on the lower portion of the board  22  on an opposite side with respect to the body case  14  and is attached to the board  22  with screws (not shown) or the like while opposing the board  22 . Note that in the present exemplary embodiment, although the board  22  and the power source board  24  are separate components, the board  22  and the power source board  24  may be an integral component. 
         [0029]    The shield cover  26  is disposed on the side of the board  22  that is opposite to the power source board  24 . The shield cover  26  is a metal cover member that shields a radio wave. The shield cover  26  is attached to the body case  14  with screws (not shown) or the like while covering the power source board  24  from the cover case  16  side. 
         [0030]    A built-in unit  28  is attached to an upper portion of the body case  14 . In a broad way, the built-in unit  28  is formed in a rectangular parallelepiped shape in which the longitudinal direction is the height direction of the housing  12 . The built-in unit  28  includes a filter unit  54  and a unit housing  30  that accommodates the filter unit  54 , which are described later. 
         [0031]    An upper portion of the unit housing  30  is attached to the body case  14  through an upper bracket  32 , and a lower portion thereof is attached to the power source board  24  and the body case  14  through a lower bracket  34 . 
         [0032]    Referring next to the functional blocks illustrated in  FIG. 4 , various functions of the radio device  10  will be described. 
         [0033]    The radio device  10  includes a power source control unit  40 , a common public radio interface (CPRI) unit  46 , a distortion compensation processing unit (a distorter or a transmitter)  48 , converter units (converters)  50 , amplifier units (amplifiers)  52 , and the filter unit  54 . 
         [0034]    The power source control unit  40  controls the electric power supplied from the power source (not shown) and supplies the electric power to the board  22  and the built-in unit  28 . The CPRI unit  46  is connected to the radio control devices such as the BBU described above through the optical cable  42  and an optical module  44 . The CPRI unit  46  is a protocol interface with the radio control device and, in accordance with a protocol, performs processing on the signals transmitted to and received from the radio control device. Furthermore, the CPRI unit  46  includes a transmission/reception separating unit  46 A that separates the digital signal input from the radio control device and the digital signal that is output to the radio control device from each other. 
         [0035]    The distortion compensation processing unit  48  performs distortion compensation on the digital signal input from the CPRI unit  46  and outputs the signal to the converter units  50 . Each converter unit  50  includes a D/A converter  50 A, a transmission frequency converter  50 B, a reception frequency converter  50 C, and an A/D converter  50 D. 
         [0036]    Each D/A converter  50 A converts the digital signal input from the CPRI unit  46  to an analog signal and outputs the analog signal to the corresponding transmission frequency converter  50 B. Each transmission frequency converter  50 B converts the frequency and the like of the analog signal input from the corresponding D/A converter  50 A and outputs the analog signal to the corresponding amplifier unit  52 . Note that each transmission frequency converter  50 B includes, for example, the electronic components  60 A such as an amplifier (a power amplifier) that amplifies the analog signal that is output to the corresponding amplifier unit  52 . 
         [0037]    Each amplifier unit  52  further amplifies the analog signal input from the corresponding converter unit  50  and outputs the analog signal to the filter unit  54 . Each amplifier unit  52  includes, for example, a plurality of (four in the present exemplary embodiment) electronic components  60 B,  60 C,  60 D, and  60 E such as an amplifier (a power amplifier) that amplifies the analog signal output to the filter unit  54 . Note that in the following description, the electronic components  60 A,  60 B,  60 C,  60 D, and  60 E are collectively referred to as electronic components  60 . Furthermore, the electronic components  60  are an example of heat generating components that generate heat by consuming electric power. 
         [0038]    For example, the filter unit  54  limits the analog signals input from the converter units  50  to a predetermined frequency band and outputs the analog signals to the antenna  58  through an antenna connector  56 . Meanwhile, the analog signals received by the antenna  58  are output to the filter unit  54  through the antenna connector  56 . The filter unit  54  includes a transmission/reception separating unit  54 A. Then, the analog signals input from the antenna  58  are separated, with the transmission/reception separating unit  54 A, from the analog signals input from the amplifier unit  52  and are output to the reception frequency converter  50 C of the converter unit  50 . 
         [0039]    The reception frequency converter  50 C converts the frequency of the analog signals input from the filter unit  54  and outputs the analog signals to the A/D converter  50 D. Each A/D converter  50 D converts the analog signal input from the corresponding reception frequency converter  50 C to a digital signal and outputs the digital signal to the CPRI unit  46 . 
         [0040]    The digital signals input to the CPRI unit  46  from the A/D converters  50 D are separated, with the transmission/reception separating unit  46 A, from the digital signals input from the optical module  44  and are output to the radio control device through the optical module  44 . 
         [0041]    Note that the amount of heat generated by the electronic components (the heat generating components)  60  of the converter units  50  and the amplifier units  52  is larger than the amount of heat generated by the electronic components (not shown) of the CPRI unit  46  and the distortion compensation processing unit  48 . Accordingly, the converter units  50  and the amplifier units  52  are high-heat resistance units in which the heat resistance temperatures of the electronic components  60  are higher than the heat resistance temperatures of the electronic components (not shown) of the CPRI unit  46  and the distortion compensation processing unit  48 . In other words, the CPRI unit  46  and the distortion compensation processing unit  48  are low-heat resistance units in which the heat resistance temperatures of the electronic components are lower than the heat resistance temperatures of the electronic components  60  of the converter units  50  and the amplifier units  52 . 
         [0042]    Furthermore, air inside the housing  12  that has been heated by the CPRI unit  46 , the distortion compensation processing unit  48 , the electronic components  60  of the converter units  50  and the amplifier units  52 , and the like moves to the upper portion of the housing  12  as illustrated by arrows Y in  FIG. 5 . Accordingly, in the housing  12 , the upper portion tends to become higher in temperature than the temperature of the lower portion. 
         [0043]    Accordingly, as illustrated in  FIG. 5 , in the present exemplary embodiment, the converter units  50  and the amplifier units  52  that are high-heat resistance units are mounted on the upper portion (the upper area) of the board  22 , and the CPRI unit  46  and the distortion compensation processing unit  48  that are low-heat resistance units are mounted on the lower portion (the lower area) of the board  22 . In other words, the CPRI unit  46  and the distortion compensation processing unit  48  that are low-heat resistance units are disposed on the lower side of the housing  12  in the height direction with respect to the converter units  50  and the amplifier units  52  that are high-heat resistance units. 
         [0044]    More specifically, the amplifier units  52 , the converter units  50 , the distortion compensation processing unit  48 , and the CPRI unit  46  are mounted on the board  22  in the order of, from the upper side of the housing  12  in the height direction, the amplifier units  52 , the converter units  50 , the distortion compensation processing unit  48 , and the CPRI unit  46 . With the above, influence of heat on the distortion compensation processing unit  48  and the CPRI unit  46 , which are low-heat resistance units, is reduced. 
         [0045]    Note that the radio device  10  according to the present exemplary embodiment includes two pairs of converter units  50  and amplifier units  52  that share the CPRI unit  46  and the distortion compensation processing unit  48 . The two pairs of converter units  50  and amplifier units  52  have similar configurations and are disposed so as to be arranged in the width direction (the arrow W direction) of the board  22 . Note that the number of converter units  50  and the number of amplifier units  52  may be appropriately changed. 
         [0046]    Furthermore, the plurality of electronic components  60 A,  60 B,  60 C, and  60 D of the converter units  50  and the amplifier units  52  are arranged along the radiation member  20  (see  FIG. 3 ) in the height direction of the housing  12 . In a similar manner, the electronic components  60 A,  60 B,  60 C, and  60 E are arranged along the radiation member  20  (see  FIG. 3 ) in the height direction of the housing  12 . Furthermore, the electronic components  60 A and  60 B, the electronic components  60 B and  60 C, the electronic components  60 C and  60 D, and the electronic components  60 C and  60 E that are adjacent to each other in the height direction of the housing  12  are connected to each other in the height direction of the housing  12  through wiring  62 . Note that the wiring  62  is, for example, a printed circuit or the like that is printed on the board  22 . 
         [0047]    More specifically, as illustrated in  FIG. 6 , the electronic components  60 A and  60 B that are adjacent to each other in the height direction of the housing  12  includes, although not shown, electrodes at upper end portions  60 A 1  and  60 B 1 , respectively, and electrodes at lower end portions  60 A 2  and  60 B 2 , respectively, in which the upper and lower end portions are two end portions of the electronic components  60 A and  60 B in the height direction of the housing  12 , for example. Furthermore, the upper end portion  60 A 1  of the electronic component  60 A on the lower side and the lower end portion  60 B 2  of the electronic component  60 B on the upper side are connected to each other through the wiring  62  extending in the height direction of the housing  12 . With the above, the signal paths of the electronic components  60  that are formed by the wiring  62  are formed, in a broad way, in the height direction of the housing  12 . 
         [0048]    Note that the wiring  62  is an example of a piece of wiring. Furthermore, “the plurality of electronic components arranged in the height direction of the housing” described herein denotes that the plurality of electronic components  60  are not arranged in the width direction of the housing  12  as is the case of a radio device  100  according to a comparative example described later. Accordingly, not limited to a case in which the plurality of electronic components  60  are arranged on a straight line extending in the height direction of the housing  12 , the plurality of electronic components  60  may be disposed while being displaced in the width direction of the housing  12  as long as, in a broad way, the plurality of electronic components  60  are arranged in the height direction of the housing  12 . 
         [0049]    Furthermore, “the electronic components adjacent to each other in the height direction of the housing are connected in the height direction of the housing through the wiring” described herein denotes that the adjacent electronic components  60  are not connected in the width direction of the housing  12  as is the case of the radio device  100  according to the comparative example described later. Accordingly, the electronic components  60  that are adjacent to each other in the height direction of the housing  12  may be connected by wiring that is bent in a crank shape or by curved wiring as long as, in a broad way, the electronic components  60  that are adjacent to each other are arranged in the height direction of the housing  12 . Note that in the present exemplary embodiment, the wiring  62  connecting each electronic component  60 A and the corresponding electronic component  60 B extends in a straight line and in the height direction of the housing  12 . 
         [0050]    Effects of the first exemplary embodiment will be described next. 
         [0051]    According to the present exemplary embodiment, the radiation member  20  is provided in the height direction of the housing  12  and on the external surface  14 A of the body case  14  that constitutes the housing  12  of the radio device  10 . Furthermore, the board  22  is accommodated inside the housing  12  and in the height direction of the housing  12 . The board  22  is capable of exchanging heat with the radiation member  20  through the body case  14 . 
         [0052]    With the above, the heat generated by the electronic components  60  and the like that are mounted on the board  22  is radiated to the outside of the housing  12  through the board  22 , the body case  14 , and the radiation member  20 . Accordingly, rise in temperature of the electronic components  60  is alleviated and, consequently, damage and the like of the electronic components  60  and the like are suppressed. 
         [0053]    Due to, for example, limitations in the insulation space and the like of the radio base station, reduction in size of the radio device  10  is in demand. However, when the size of the radio device  10  is reduced, the size of the radiation member  20  is also reduced. Accordingly, the amount of heat radiated from the inside of the housing  12  to the outside of the housing  12  through the radiation member  20  decreases. Accordingly, for example, in a case in which the total amount of heat generated by the plurality of electronic components  60  and the like are the same before and after the miniaturization of the radio device  10 , the temperature rises more easily inside the housing  12  of the radio device  10  after miniaturization and, consequently, the electronic components  60  and the like become damaged more easily. 
         [0054]    Conversely, in the present exemplary embodiment, the housing  12  of the radio device  10  is formed in a rectangular parallelepiped shape in which the longitudinal direction is the height direction. With the above, compared with, for example, a case in which the housing  12  is formed in a rectangular parallelepiped shape in which the longitudinal direction is the width direction, in the present exemplary embodiment, the moving path (the arrows Y in  FIG. 5 ) of the air inside the housing  12  moving in the height direction inside the housing  12  while exchanging heat which the radiation member  20  (see  FIG. 3 ) is long. Accordingly, the efficiency of heat radiated from the inside of the housing  12  to the outside of the housing  12  through the radiation member  20  is improved. 
         [0055]    As described above, in the present exemplary embodiment, while reducing the size of the radio device  10  in the width direction, the efficiency of heat, which is generated inside the housing  12  by the electronic components  60  and the like, radiated to the outside of the housing  12  through the radiation member  20  may be increased. 
         [0056]    Furthermore, as illustrated in  FIG. 5 , in the present exemplary embodiment, the distortion compensation processing unit  48  and the CPRI unit  46  that are low-heat resistance units are disposed on the lower side with respect to the converter units  50  and the amplifier units  52  that are high-heat resistance units. With the above, the damage and the like of the electronic components in the distortion compensation processing unit  48  and the CPRI unit  46  are suppressed in a rational manner. 
         [0057]    Furthermore, in the present exemplary embodiment, the electronic components  60 A,  60 B,  60 C, and  60 D and the electronic components  60 A,  60 B,  60 C, and  60 E of the converter units  50  and the amplifier units  52  are arranged in the height direction of the housing  12  along the radiation member  20 . Furthermore, the electronic components  60  that are adjacent to each other in the height direction of the housing  12  are connected in the height direction of the housing  12  through the wiring  62 . With the above, while shortening the length of the wiring  62 , the efficiency of heat radiated from the inside of the housing  12  to the outside of the housing  12  through the radiation member  20  may be improved. 
         [0058]    Furthermore, in the present exemplary embodiment, the optical module  44  is disposed on the lower end side of the board  22 . In other words, the optical module  44  is disposed on the lower end side of the unit housing  30 . With the above, the optical module  44  whose heat resistance temperature is low may be set apart from the converter units  50  and the amplifier units  52  whose amount of heat generation is high. Accordingly, damage and the like of the optical module  44  are suppressed. Furthermore, connecting operation of the optical cable  42  to the optical module  44  and wiring of the optical cable  42  are facilitated. Note that the optical module  44  is an example of a low-heat resistance unit. 
         [0059]    The radio device  100  according to a comparative example will be described next. As illustrated in  FIG. 7 , the radio device  100  (a housing) according to the comparative example is lower in height and is wider in width than the radio device  10  (the housing  12 ) according to the present exemplary embodiment. Due to the above, a board  102  of the radio device  100  according to the comparative example is lower in height and is wider in width than the board  22  of the radio device  10  according to the present exemplary embodiment. 
         [0060]    In the above case, in the radio device  100  according to the comparative example, a moving path of the air moving inside the housing (not shown) in the height direction becomes shorter than that of the radio device  10  according to the present exemplary embodiment. Accordingly, compared with the radio device  10  according to the present exemplary embodiment, the amount of heat radiated to the outside of the housing  12  from the inside of the housing  12  through the radiation member  20  is decreased in the radio device  100  according to the comparative example. 
         [0061]    Furthermore, compared with the radio device  10  according to the present exemplary embodiment, the mounting space of the electronic components  60  and the like in the height direction of the board  102  is smaller in the radio device  100  according to the competitive example. Accordingly, in the converter units  50  and the amplifier units  52  of the radio device  100 , for example, the two electronic components  60 B and  60 C are arranged in the width direction (arrow W direction) of the board  102  and are connected to each other through wiring  62  that linearly extends in the width direction of the board  102 . Accordingly, the length of the wiring  62  is long in the radio device  100  according to the comparative example. 
         [0062]    Conversely, in the present exemplary embodiment, as described above, while reducing the size of the radio device  10  in the width direction of the housing  12  (the board  22 ), the efficiency of heat radiated from the inside of the housing  12  to the outside of the housing  12  through the radiation member  20  may be improved. 
         [0063]    Furthermore,  FIG. 8  illustrates a temperature distribution in the board  22  of the radio device  10  according to the present exemplary embodiment obtained through simulation. On the other hand,  FIG. 9  illustrates a temperature distribution in the board  102  of the radio device  100  according to the comparative example obtained through simulation. As illustrated in  FIGS. 8 and 9 , the temperature of the upper portion of the housing  12  in the radio device  10  according to the present exemplary embodiment was lower than that in the radio device  100  according to the comparative example. Note that in  FIGS. 8 and 9 , as the colors of the boards  22  and  102  becomes lighter, the temperature becomes lower, and as the colors of the boards  22  and  102  becomes deeper, the temperature becomes higher. 
         [0064]    A description of a second exemplary embodiment will be given next. Note that members and the like that are similar to those of the first exemplary embodiment are denoted with the same reference numerals as those of the first exemplary embodiment and detailed descriptions thereof are appropriately omitted. 
         [0065]    As illustrated in  FIG. 10 , in a radio device  70  according to the second exemplary embodiment, the built-in unit  28  is attached to a shield cover  72 . 
         [0066]    Specifically, the shield cover  72  is attached to the body case  14  with screws (not shown) and the like while covering the board  22  and the power source board  24 . With the above, the shield cover  72  is capable of exchanging heat with the radiation member  20  through the body case  14 . Note that the shield cover  72  may be attached to the board  22 . In such a case, the shield cover  72  is capable of exchanging the with the radiation member  20  through the board  22  and the body case  14 . 
         [0067]    The shield cover  72  includes an opposing wall portion  74  that opposes the board  22  and the power source board  24 . A surface of the opposing wall portion  74  on the opposite side with respect to the board  22  and the power source board  24  is an attaching surface  74 A to which a lateral side  30 S of the built-in unit  28  (the unit housing  30 ) is attached through a thermally-conductive sheet  76 . 
         [0068]    The thermally-conductive sheet (a heat radiation sheet)  76  is formed in a sheet shape with silicon or the like that has high thermal conductivity. The thermally-conductive sheet  76  is disposed between the attaching surface  74 A of the shield cover  72  and the lateral side  30 S of the built-in unit  28 . With the above, the lateral side  30 S of the built-in unit  28  is adhered to the attaching surface  74 A of the shield cover  72 . 
         [0069]    An adjustment screw member  78  that adjusts the setting of the filter unit  54  inside the built-in unit  28  is provided in the lateral side  30 S of the built-in unit  28  on the board  22  side. The adjustment screw member  78  includes a head  78 A to which a tool such as a screwdriver is engaged, and the adjustment screw member  78  is inserted into an attachment hole formed in the lateral side  30 S of the built-in unit  28 . The setting of the filter unit  54  is changed by rotating the adjustment screw member  78  with a tool such as a screwdriver. 
         [0070]    Furthermore, a recess  80  in which the head  78 A of the adjustment screw member  78  is accommodated is formed in the lateral side  30 S of the built-in unit  28 . The entire head  78 A of the adjustment screw member  78  is accommodated in the recess  80 . With the above, the head  78 A of the adjustment screw member  78  is positioned not so as to interfere with the attaching surface  74 A of the shield cover  72 . 
         [0071]    Effects of the second exemplary embodiment will be described next. 
         [0072]    In the radio device  70  according to the second exemplary embodiment, the built-in unit  28  is attached to the body case  14  through the shield cover  72 . With the above, the heat of the built-in unit  28  is radiated from the radiation member  20  to the outside of the housing  12  through the shield cover  72  and the body case  14 . Accordingly, the rise in temperature of the built-in unit  28  is alleviated and, consequently, damage and the like of the filter unit  54  are suppressed. 
         [0073]    Furthermore, the lateral side  30 S of the built-in unit  28  is adhered to the attaching surface  74 A of the shield cover  72  through the thermally-conductive sheet  76 . With the above, the transmission efficiency of the heat transmitted from the built-in unit  28  to the shield cover  72  is improved. Accordingly, the rise in temperature of the built-in unit  28  is alleviated further. 
         [0074]    Furthermore, the adjustment screw member  78  is attached to the lateral side  30 S of the built-in unit  28 . The head  78 A of the adjustment screw member  78  is accommodated in the recess  80  formed in the lateral side  30 S of the built-in unit  28 . With the above, the head  78 A of the adjustment screw member  78  is positioned not so as to interfere with the attaching surface  74 A of the shield cover  72 . Accordingly, adhesion between the lateral side  30 S of the built-in unit  28  and the attaching surface  74 A of the shield cover  72  is secured. 
         [0075]    As described above, in the present exemplary embodiment, the heat of the built-in unit  28  is efficiently radiated to the outside of the housing  12  from the radiation member  20  through the shield cover  72  and the body case  14 . Accordingly, damage and the like of the filter unit  54  inside the built-in unit  28  are suppressed. 
         [0076]    Furthermore, in the present exemplary embodiment, the built-in unit  28  and the radiation member  20  are connected to each other through the shield cover  72  so as to be capable of exchanging heat. With the above, compared with a case in which the built-in unit  28  and the radiation member  20  are connected to each other so as to be capable of exchanging heat through a heat conduction member that is additionally provided, the number of components may be suppressed. 
         [0077]    Note that in the present exemplary embodiment, although heat exchange is performed between the built-in unit  28  in the radiation member  20  through the shield cover  72 , heat exchange may be performed between the built-in unit  28  and the radiation member  20  through the upper bracket  32 . 
         [0078]    Furthermore, in a case in which the shield cover  72  and the built-in unit  28  are connected to each other so as to be capable of exchanging heat, the thermally-conductive sheet  76  and the recess  80  for the adjustment screw member  78  may be omitted. 
         [0079]    Modifications of the first and second exemplary embodiments described above will be described next. 
         [0080]    In the first and second exemplary embodiments described above, the radiation member  20  includes the plurality of radiation fins  22 F; however, the shape and the like of the radiation fins  22 F may be appropriately changed. Furthermore, the radiation member may be various heatsinks. Furthermore, not limited to the air-cooled radiation member, the radiation member may be a water-cooling radiation member. 
         [0081]    Furthermore, not limited to a radio device that constitutes a portion of a portable base station, the first and second exemplary embodiments may be appropriately applied to other radio devices. 
         [0082]    While the first and second embodiments of the technique disclosed in the present application has been described above, the technique disclosed in the present application is not limited to the above first and second exemplary embodiments. Furthermore, the above-described first and second exemplary embodiments and various modifications may be appropriately combined and may be modified without departing from the spirit and scope of the technique disclosed in the present application. 
         [0083]    All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.