PURPOSE: To prevent a mode conversion loss eliminating need for mode conversion by connecting the power receiving point of the microstrip antenna and a down-converter with a microstrip line.

CONSTITUTION: The power receiving point 18 of a microstrip section 12 and the input section 32 of a down-converter 30 are connected with a microstip line 60. A strip 64 made of a copper foil whose thickness is 10μm is formed to one side of a strip line member 62 made of a polyester film whose thickness is 38μm to form the strip line 60. The strip 64 of the strip line 60, the power receiving point 18 and the input section 32 of the down-converter 30 are connected electrically by a conductive adhesives including silver powder or the like. Then in order to increase the strength of the connection part, the strip line member 62, the strip member 16, the board 46 of the down-converter 30 are adhered by an adhesive. Thus, it is not required to implement mode conversion twice and no mode conversion loss is caused.