a preferred embodiment of the present invention will be described with respect to drawings . fig1 generally illustrates a configuration of a mobile terminal device 1 according to an example of a preferred embodiment of the invention . the mobile terminal device 1 has two housings 14 and 15 that are approximately rectangular parallelpipeds . the housing 14 has an input unit 10 , and the housing 15 has a display unit 11 . further , the housings 14 and 15 are connected by a joint unit 13 at a point at the center of their edge , and can be moved in the direction of opening / closing the housings . the housing 15 can be rotated at least 180 ° with the housing 15 perpendicular to the housing 14 . thus , the mobile terminal device 1 may be used as a usual laptop pc as shown in fig1 , or as a handheld pc that has a touch panel input unit 16 and the like by rotating the housing 15 at the joint unit 13 as shown in fig2 and folding the housing 15 with the display unit onto the housing 14 that has the input unit 10 as illustrated in fig3 and 4 . here , a laptop pc is not limited to such one shown in fig1 , but it may be a so - called portable personal computer that has parts such as a cpu , memory , hard disk device , keyboard , display panel and the like . also , a handheld pc is not limited to such one shown in fig4 , but it may be a so - called portable computer or an information processing terminal that also has a cpu , memory , hard disk device , touch panel , pen input panel or display panel as input means . further , devices falling within categories called electronic organizer or pda may be also included . also , the terminal device may include a keyboard as input means . as shown in fig5 , the mobile terminal device 1 has a first antenna 100 and a second antenna 110 on each of two sides of the housing 15 that supports the display unit 11 . these antennas are connected to a wireless lan card 120 and the antennas and the lan card operate in cooperation to realize communication means of the mobile terminal device 1 . the mobile terminal device 1 further includes a display orientation rotation button 17 on the same surface as the display unit 11 of the housing that supports the display unit 11 . by pressing the button 17 , a user can change the orientation of display on the display unit 11 by a predetermined angle , e . g ., 90 ° and 180 °. the display orientation rotation button 17 may be provided at any position on the housings of the mobile terminal device 1 as long as it may be operated both when the terminal device 1 is used as a laptop pc ( fig1 , for example ) and as a handheld pc ( fig4 , for example ). further , the display orientation of the display unit 11 may be automatically changed based on the difference in positional relationship of the two housings for the case the terminal is used as a laptop pc as shown in fig1 and the case it is used as a handheld pc as shown in fig4 . fig5 illustrates the display orientation of the mobile terminal device 1 in a first portrait display mode . in an example of the preferred embodiment of the invention , in this display mode , it is determined that the second antenna 110 that is positioned lower relative to the display orientation is closer to the user &# 39 ; s body , and the second antenna 110 is disabled in consideration of the way the user holds the terminal device 1 . fig6 illustrates the display orientation of the mobile terminal device 1 in a second portrait display mode . the display orientation in this mode is shifted 180 ° from the first portrait display mode shown in fig5 . the user of the mobile terminal device 1 can switch between these display modes by pressing the display orientation rotation button 17 . in an example of the preferred embodiment of the invention , in this display mode , it is determined that both the first antenna 100 and second antenna 110 are away from the user &# 39 ; s body and both the antennas are enabled considering the way the user holds the terminal device 1 . in this case , an antenna with better use conditions is selected for use by a known method conventionally employed . further , as illustrated in fig7 , in a first landscape display mode of the mobile terminal device 1 , the first antenna 100 positioned lower relative to the display orientation is considered to be closer to the user &# 39 ; s body considering how the user holds the terminal device 1 , and the first antenna 100 is disabled . when in a second landscape display mode of the mobile terminal device 1 as shown in fig8 , it is determined that both the first antenna 100 and second antenna 110 are away from the user &# 39 ; s body considering how the user holds the terminal device 1 , and both the antennas are enabled . in this case , an antenna with better use conditions is selected for use by a known method conventionally employed . thus , according to the invention , an antenna positioned lower relative to display orientation is considered to be closer to the user &# 39 ; s body and can be automatically disabled taking into consideration how the user holds the terminal . consequently , an antenna closer to the hand or body of the user holding the mobile terminal device i is disabled and only an antenna farther from the user &# 39 ; s hand or body is enabled , so that sar on the human body can be minimized while the user can use wireless communication all the time . alternatively , an acceleration sensor may be included in the housing of the mobile terminal device 1 and any of the four usages shown in fig5 - 8 may be determined from the orientation of holding the terminal that is detected by the acceleration sensor . specifically , if an antenna exists on a side that is determined to be positioned downmost among the four sides of the housing , it is determined that the antenna is closer to the user &# 39 ; s body and is disabled . in this case , the determination can be made without using information on the display orientation on the display unit 11 . further , the display orientation of the display unit may be automatically changed according to the determination of the vertical relationship of the housings . this allows the display orientation of the display unit 11 to be changed and an antenna more suitable for the display orientation to be selected without the user pressing the display orientation rotation button 17 whenever the user changes the way of holding the mobile terminal device 1 . also , when the mobile terminal device 1 is connected to a docking station ( i . e ., used as a laptop pc ), the connection may be detected by a sensor , and both the first and second antennas 100 and 110 may be enabled regardless of the display orientation by the instruction for the terminal detected by an acceleration sensor . in this case , an antenna with better use conditions would be selected for use by a known method conventionally employed . fig9 illustrates a hardware configuration of the mobile terminal device 1 of the invention . a control unit 140 controls the entire mobile terminal device 1 . the mobile terminal device 1 also has a communication control unit 130 that includes an antenna control unit 131 for controlling the first and second antennas 100 and 110 . the antenna control unit 131 determines an antenna to be disabled and stops the use of the antenna according to the determination as described earlier . the mobile terminal device 1 may include an acceleration sensor 150 . the mobile terminal device may also include a docking sensor 160 for detecting whether the terminal device 1 is connected to a docking station . using detection result by these sensors , the antenna control unit 131 controls the antennas in cooperation with the control unit 140 as mentioned above . these pieces of hardware are interconnected by a bus 180 . programs stored in a storage unit 170 are read out and executed as necessary by the control unit 140 , causing the pieces of hardware to cooperate to realize the various means of the invention . as can be readily appreciated by those skilled in the art , the acceleration sensor 150 is available in various mechanisms , such as one that is combination of piezoelectric ceramic device and electrodes . when acceleration ( gravitational acceleration in resting state , for example ) is externally applied to the piezoelectric ceramic devices , the piezoelectric ceramic devices distort to generate stress internally . the stress is converted to electric signal ( electric charge ) with piezoelectric effect and the direction and magnitude of the acceleration can be detected from the electric signal . this allows the direction of the gravitational acceleration to be detected in resting state , and the orientation in which the mobile terminal device 1 is held can be calculated from the direction . fig1 illustrates a functional configuration of the mobile terminal device 1 according to an example of the preferred embodiment of the invention . the control unit 140 controls the entire mobile terminal device 1 . the control unit 140 provides various functions of the mobile terminal device 1 in conjunction with the antenna control unit 131 for controlling the first and second antennas 110 and 110 , a built - in button controller 240 for controlling built - in buttons such as the display orientation rotation button 17 , and a graphic controller 250 for controlling the display unit 11 . on an operating system ( os ) 200 , various user applications such as a word processor can run . the os 200 drives various pieces of hardware via the control unit 140 , antenna control unit 131 , built - in button controller 240 , and graphic controller 250 by way of kernel - level process groups that consist of a built - in button driver 220 , a graphic driver 230 and the like . in an example of the preferred embodiment of the invention , when the user presses the display orientation rotation button 17 of the mobile terminal device 1 , the built - in button controller 240 senses the pressing . the built - in button controller 240 then informs the os 200 of the pressing via the built - in button driver 220 . the os 200 sends a command for rotating the screen by a predetermined rotation angle ( e . g ., 90 °) to the graphic controller 250 via the graphic driver 230 . the graphic controller 250 receives the command and rotates the display orientation of the display unit 11 ( e . g ., 90 °) accordingly . further , upon detecting the pressing of the display orientation rotation button via the os 200 and the like , the control unit 140 confirms the display orientation of the display unit 11 to the os 200 . the os 200 obtains information on display orientation from the graphic controller 250 via the graphic driver 230 . the control unit 140 obtains the information on display orientation from the os 200 , determines whether to disable / enable the first and / or second antennas based on the information on display orientation , and executes the determination via the antenna control unit 131 . fig1 illustrates a functional configuration of the mobile terminal device 1 according to another example of the preferred embodiment of the invention . as in fig1 , the control unit 140 controls the entire mobile terminal device 1 . the control unit 140 provides various functions of the mobile terminal device 1 in conjunction with the antenna control unit 131 for controlling the first and second antennas 100 and 110 , a device controller 270 for controlling the acceleration sensor 150 and docking sensor 160 , and a graphic controller 250 for controlling the display unit 11 . on the operating system ( os ) 200 , various user applications such as a word processor can run . the os 200 drives various pieces of hardware via the control unit 140 , antenna control unit 131 , device controller 270 , and graphic controller 250 or the like , by way of kernel - level process groups that consist of the device driver 260 and graphic driver 230 . in another example of the preferred embodiment of the invention , when the user changes the orientation of holding the terminal , the acceleration sensor 150 detects the change . when the change in holding orientation is detected , the change is informed to the os 200 via the device driver 260 . the control unit 140 is informed of the change by the os 200 , and based on the information on the change , determines whether to disable / enable the first and / or second antennas and executes the determination via the antenna control unit 131 . further , in yet another example of the preferred embodiment of the invention , the docking sensor 160 senses the connection of the mobile terminal device 1 to a docking station ( not shown ). in this case , as with the acceleration sensor 150 , the control unit 140 recognizes the connection and changes the display orientation of the display unit 11 to the second landscape display mode shown in fig8 via the graphic controller 250 . further , the control unit 140 enables both the first and second antennas via the antenna control unit 131 . here , an antenna with better use conditions is selected for use by a known method conventionally employed . fig1 is a flow diagram illustrating the flow of antenna control according to an example of the preferred embodiment of the invention . first , the control unit 140 determines whether or not the display orientation rotation button 17 has been pressed ( step s 01 ). if it determines that the button has been pressed , the control unit 140 queries the os ( operating system ) running on the mobile terminal device 1 about the display orientation of the display unit 11 ( step s 02 ). if the query returns the first portrait display mode shown in fig5 ( step s 03 ), the antenna control unit 131 disables the second antenna 110 ( step s 04 ). on the other hand , the query returns the second portrait display mode shown in fig6 ( step s 05 ), the antenna control unit 131 enables both the first and second antennas 100 and 110 ( step s 06 ). in the latter case , an antenna with better use conditions is selected for use by a known method conventionally employed . if the query returns the first landscape display mode shown in fig7 ( step s 07 ), the antenna control unit 131 disables the first antenna 100 ( step s 08 ). if the query returns the second landscape display mode shown in fig8 ( step s 09 ), the antenna control unit 131 enables both the first and second antennas 100 and 110 ( step s 10 ). in the latter case , an antenna with better use conditions is selected for use by a known method conventionally employed . in this manner , control starting from step s 01 is repeated until the use of the mobile terminal device ends ( step s 11 ). fig1 is a flow diagram illustrating the flow of antenna control according to another example of the preferred embodiment of the invention . first , the control unit 140 determines whether or not the holding orientation of the mobile terminal device 1 has changed ( step s 101 ). then , if the control unit 140 determines that the holding orientation has changed and that the second side shown in fig5 is at the bottom ( step s 103 ), the antenna control unit 131 disables the second antenna 110 ( step s 104 ). meanwhile , if the control unit 140 determines that the holding orientation has changed and that the fourth side shown in fig5 is at the bottom ( step s 105 ), the antenna control unit 131 enables both the first and second antennas 100 and 110 ( step s 106 ). in the latter case , an antenna with better use conditions is selected for use by a known method conventionally employed . if the control unit 140 determines that the holding orientation has changed and that the first side shown in fig5 is at the bottom ( step s 107 ), the antenna control unit 131 disables the first antenna 100 ( step s 108 ). if the control unit 140 determines that the holding orientation has changed and that the third side shown in fig5 is at the bottom ( step s 109 ), the antenna control unit 131 enables both the first and second antennas 100 and 110 ( step s 110 ). in the latter case , an antenna with better use conditions is selected for use by a known method conventionally used . control starting at step s 101 is repeated in such a manner until the use of the mobile terminal device ends ( step s 111 ). fig1 is a flow diagram illustrating the flow of antenna control according to yet another example of the preferred embodiment of the invention . initially , the control unit 140 determines whether or not the mobile terminal device 1 has been connected to a docking station ( step s 121 ). if the control unit 140 determines that the terminal is connected to the docking station , the control unit 140 changes the display orientation of the display unit 11 to the second landscape display mode of fig8 ( step s 122 ), and the antenna control unit 131 enables both the first and second antennas 100 and 110 ( step s 123 ). here , an antenna with better use conditions is selected for use by a known method conventionally employed . control starting at step s 121 is repeated in such a manner until use of the mobile terminal device ends ( step s 124 ). although the above embodiments describes a case where the mobile terminal device 1 has two antennas , if the terminal device has three or more antennas , any antenna that is positioned lower relative to the display orientation of the display unit can be disabled in the same way . also , any antenna that is positioned downmost as determined by an acceleration sensor can be disabled in the same way as described above . also , although use of an antenna with its transmission output reduced is not necessarily required in the preferred embodiment of the invention , the invention is not intended to deny the use of such an antenna . for example , it is also possible that the terminal device has more antennas and transmission output of some of the antennas is reduced . if not otherwise stated herein , it is to be assumed that all patents , patent applications , patent publications and other publications mentioned and cited herein are hereby fully incorporated by reference herein as if set forth in their entirety herein . while the embodiment of the present invention has been described , the description only illustrates specific examples and does not limit the invention particularly . also , the operation mentioned in the embodiment of the invention only illustrates specific examples and the operation provided by the present invention is not limited to that described in the embodiment of the invention .