ANTENNA DEVICE

PURPOSE:To make working and assembling easy to obtain an airtight structure economically by providing a gas charging hole in one of a shield plate, a main reflective mirror, and a radome in an antenna device of millimeter wave and submillimeter wave bands. CONSTITUTION:In a Cassegrain antenna consisting of a main reflective mirror 1, an auxiliary reflective mirror 2, a primary radiator 3, a shield plate 4, a radome 5, and a pole brace 6, an airtight structure is given to the internal space surrounded with the main reflective mirror 1, the shield plate 4, and the radome 5, and a gas charging hole 10 is provided in a part of the shield plate 4. Thus, it is unnecessary to attach a feedome, and working is made easier in comparison with the case where the charging hole is provided in a feeding waveguide 7, and dew condensation and rust on the inside are prevented.