| 摘要 |
A high dielectric is fixed to the side of an opening of a casing made from a good electroconductive material or is fixed to the side of an opening of an outer shell made from an insulator such as ferrite, and an antenna element is fixed on the back surface of the high dielectric. A material body, which has a small relative dielectric constant such as air is stored in the casing or the outer shell. The antenna element is sandwiched between the material body having the small relative dielectric constant and the high dielectric. The high dielectric is formed from a material having a relative dielectric constant that is close to the relative dielectric constant of a medium material such as clay, sand, water and the like in the underground or the underwater. When the electromagnetic wave is transmitted to the underground or the underwater or the electromagnetic wave is received from the underground or the underwater, the casing or the outer shell is buried in the underground or the underwater or is caused to approach the underground or the underwater.
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