throughout this description , the embodiments and examples shown should be considered as exemplars , rather than limitations on the apparatus and methods of the present invention . wireless tags according to an embodiment of the present invention will be described in detail , with reference to the accompanying drawings . fig1 a is a plan view showing a wireless tag according to a first embodiment , which remains in the initial state . the wireless tag 10 has a base 12 , an ic chip ( memory chip ) 14 , a base antenna 16 , and antenna seals 18 . the ic chip 14 is embedded in the base 12 . the base antenna 16 is provided on one surface of the base 12 . the antenna seals 18 are bonded to the surface of the base 12 and connected to the base antenna 16 . the base antenna 16 is connected to the ic chip 14 . the base antenna 16 and the antenna seals 18 constitute an antenna 20 . the wireless tag 10 further has various circuits ( not shown ). the circuits are : a rectifier circuit , a receiver circuit , a transmitter circuit , a power - supply circuit , and a control circuit . the rectifier circuit rectifies the ac current generated at the antenna 20 . the receiver circuit demodulates any signals it has received . the transmitter circuit modulates response signals and transmits them to a reader - writer . the power - supply circuit applies a dc voltage to the other circuits of the wireless tag 10 . the control circuit controls the other circuits of the tag 10 . the antenna seal 18 is composed of a flexible seal substrate and an antenna pattern each . the substrate is made of resin . the antenna pattern is provided on the substrate and made of conductive material such as metal . the antenna pattern has perforations 22 a and 22 b . the perforations 22 a and 22 b divide the antenna pattern into three regions 24 a , 24 b and 24 c , which are , nonetheless , electrically connected to each other . the three regions 24 a , 24 b and 24 c should preferably have different colors so that they may better be distinguished than otherwise . the antenna seals 18 are bonded to the end parts of the base antenna 16 , respectively . therefore , they make the antenna 20 symmetrical in the lengthwise direction as will be described later , when any two corresponding regions are peeled off , respectively , from the end parts of the base antenna 16 . the abbreviation “ jp ” is printed on each region 24 a , indicating that this region corresponds to the frequency band of 950 to 956 mhz at which data can be read and written , by wireless , from and into the wireless tag 10 in japan . similarly , the abbreviation “ us ” is printed on each region 24 b , indicating that this region corresponds to the frequency band of 902 to 928 mhz at which data can be read and written , by wireless , from and into the wireless tag 10 in the united states . the abbreviation “ eu ” is printed on each region 24 c , indicating that this region corresponds to the frequency band of 866 to 870 mhz at which data can be read and written , by wireless , from and into the wireless tag 10 in the members of the european unit ( not necessarily all members ). hence , while the wireless tag 10 remains in the state shown in fig1 a , the antenna 20 of the wireless tag 10 is allocated to the resonance frequency at which data can be read and written , by wireless , from and into the tag 10 in the members of the european union . the wireless tag 10 is suitable for use in the case where the frequency at which data is read and written by wireless from and into the tag 10 gradually increases as the load is transported from an area to another . assume that the wireless tag 10 is attached to a load transported from a european unit member to the united states , and thence to japan . first , in the european union member , the data about the load is written into the wireless tag 10 , and the tag 10 is attached to the load in the state shown in fig1 a . next , the load arrives at the united states . in the united states , it is practically impossible to read data by wireless from the wireless tag 10 that assumes the state shown in fig1 a . to read the data , the person who has received the load in the united states peels off the two regions 24 c , along the perforations 22 b . those parts of the base antenna 16 , which lie under the regions 24 c , are peeled off , too . as a result , the wireless tag 10 changes in configuration as is illustrated in fig1 b . as a result , the resonance frequency of the antenna 20 increases before peeling - off to change to the frequency used in the united states . hence , the data can be read from the wireless tag 10 and new data can be written into the wireless tag 10 . to avoid errors in peeling off the wireless ic seals 18 , it is desirable to print on the tag 10 arrows and phrases ( e . g ., peal , direction for peeling , or the like ), indicating the direction in which to peel off the antenna seals 18 . if the base 12 has an area available for printing , “ eu : [ jp ] [ us ] [ eu ],” “ usa : [ jp ] [ us ],” “ jpn [ jp ],” or the like may be printed , showing where the wireless tag 10 has been used and can be used . then , the load arrives at japan . in japan , it is practically impossible to read the data by wireless from the wireless tag 10 remaining in the state shown in fig1 b . to read the data , the person who has received the load peels off the two regions 24 b , along the perforations 22 a . as a result , the wireless tag 10 changes in configuration as is illustrated in fig1 c . as a result , the resonance frequency of the antenna 20 changes to the frequency used in japan . hence , the data can be read from the wireless tag 10 and new data can be written into the wireless tag 10 . thus , the wireless tag 10 is so configured that any person can easily peel off the prescribed regions of each antenna seal 18 in accordance with the marks or instructions printed on the tag 10 . hence , the wireless tag 10 can well cope with the fact that the frequency at which the data is read and written by wireless from and into the tag 10 differs from area to area . further , the amount in which the antenna seals 18 are peeled off is the same , no matter who peels them . therefore , an antenna 20 from which a person has peeled off the antenna seals 18 has the same resonance frequency as another antenna 20 from which another person has peeled off the seals 18 . this can prevent troubles in the process of reading the data from the wireless tag 10 , because of the fact that the frequency used to read and write data from and into wireless tags differs from area to area . the wireless tag 10 can of course be attached to a load to be transported from eu to us , a load to be transported from eu to jp , and a load to be transported from us to jp . fig2 is a plan view of a wireless tag 10 a that is a modification of the wireless tag 10 shown in fig1 a to 1 c . this wireless tag 10 a has a base antenna 16 that has the resonance frequency used in japan . two antenna seals 18 a are bonded to the base antenna 16 and have a perforation 22 c each . the perforation 22 c divides the antenna seal 18 a into two regions 24 d and 24 e . “ us ,” “ eu ” and “ jp ” are printed on the region 28 d , region 28 e and the base 12 , respectively . this wireless tag 10 a is used in the same way as the wireless tag 10 . that is , in any member of the european union , the wireless tag 10 a is used , having both antenna seals 18 a bonded to the base 12 , each seal 18 a having both regions 24 d and 24 e . in the united states , it is used , having both antenna seals 18 a bonded to the base 12 , each seal 18 a having the region 24 d only , with the region 24 e peeled off . in japan , it is used , with both regions 24 d and 24 e peeled off ( that is , antenna seals 18 a have been peeled off ). fig3 is a plan view showing a wireless tag 30 according to the second embodiment of this invention , which remains in the initial state . this wireless tag 30 has dielectric seals 32 in place of such antenna seals 18 a as used in the wireless tag 10 described above . that is , the wireless tag 30 comprises a base 12 , an ic chip 14 embedded in the base 12 , a base antenna 16 provided on one surface of the base 12 , and dielectric seals 32 bonded to the base antenna 16 . the dielectric seals 32 increase the floating capacitance in the base antenna 16 . the antenna 34 therefore has a higher resonance frequency than the base antennas 16 in the state illustrated in fig3 . the dielectric seals 32 are flexible substrates made of resin and fine particles of dielectric ceramic uniformly dispersed in the resin . each dielectric seal 32 has slits 36 a and 36 b . the slits 36 a and 36 b divide the dielectric seal 32 into three regions 38 a , 38 b and 39 c . the three regions 38 a , 38 b and 38 c should preferably have different colors so that they may be better be distinguished than otherwise . “ eu ,” “ us ” and “ jp ” are printed on the regions 38 a , 38 b and 38 c , respectively . these abbreviations mean the same areas as on the wireless tag 10 described above . this wireless tag 30 is suitable for use in the case where the frequency at which data is read and written by wireless from and into it gradually deceases as the load is transported from an area to another . assume that the wireless tag 30 is attached to a load transported from japan to the united states , and thence to a european union member . in this case , in japan , the data about the load is written into the wireless tag 30 , and the tag 30 is attached to the load . next , the load arrives at the united states . in the united states , the person who has received the load peels off the two regions 38 c , along the slits 36 b . at this point , only the dielectric seals are peeled off , and the base antenna 16 remains intact , as is illustrated in fig4 . as described above , the dielectric seals are substrates made of resin and fine particles of dielectric ceramic uniformly dispersed in the resin . hence , the frequency increases due to “ wave - compressing effect ” as the dielectric seals approach the base antenna 16 . the wave - compressing effect decreases when the dielectric seals are peeled off . therefore , the resonance frequency becomes lower . the resonance frequency of the antenna 34 of the wireless tag 30 therefore changes to the frequency of the electric waves used in the united states . when the load arrives at the european union member , the person who has received the load peels off the two regions 38 b , along the slits 36 a . the resonance frequency of the antenna 34 of the wireless tag 30 therefore changes to the frequency of the electric waves used in the european union member . needless to say , the wireless tag 30 can be modified in configuration in the same way as the wireless tag 10 is modified into the wireless tag 10 a . embodiments of the present invention have been described . the invention is not limited to the embodiments , nonetheless . various changes can be made within the scope of the invention . more specifically , the antenna seals used to raise the resonance frequency and the dielectric seals used to lower the resonance frequency may be both bonded to the base 12 . then , resonance frequency can be lowered if necessary after the antenna seals have been peeled and the resonance frequency has thereby been raised . conversely , the resonance frequency can be raised if necessary after the dielectric seals have been peeled and the resonance frequency has thereby been lowered . moreover , the components of the embodiments described above may be combined in any appropriate manner in order to make various inventions . for example , some of the component of any embodiment may not be used . moreover , the components of the different embodiments may be combined in any desired fashion . a specific example is such a wireless tag 40 as shown in fig5 . this tag 40 has an antenna seal 42 that has the same composition as the antenna seals 18 and bonded to only one end of the base antenna 16 , not to both ends of the base antenna 16 as the antenna seals 18 in the wireless tag 10 . this simplify the work of peeling off the antenna seal . this configuration can be applied to dielectric seals , if any , provided on the base antenna 16 . although exemplary embodiments of the present invention have been shown and described , it will be apparent to those having ordinary skill in the art that a number of changes , modifications , or alterations to the invention as described herein may be made , none of which depart from the spirit of the present invention . all such changes , modifications , and alterations should therefore be seen as within the scope of the present invention .