| 摘要 |
PROBLEM TO BE SOLVED: To enable electromagnetic waves radiating from a portable telephone main body toward a human body to be attenuated by a method wherein a perforated metal plate formed through an electron beam perforating process is used as an electromagnetic shielding material corresponding to the speaker and microphone of the portable telephone. SOLUTION: Communication radio waves are radiated from the tip of an antenna 101 which is extended high above the operator's head for most of the time when a case 1 which contains a portable telephone is disposed near an operator's head in operation. Radiowaves leaking out of a telephone main body disposed near the operator's head are markedly attenuated by the case 1 which is so formed of electromagnetic shielding material mainly made of perforated stainless steel plate subjected to EBP processing as to constitute a so-called Faraday cage, so that radiowaves leaking to irradiate a human body are markedly lessened in dosage. By this setup, a shield case of this constitution can be markedly improved in electromagnetic shielding effect SE (db) to high-energy electromagnetic waves which radiate from a portable telephone. |
