Abstract: A plane antenna comprises a stack of a radiator circuit, first and second power supply circuits and earthing conductor member which are disposed independent of one another with dielectric layers respectively interposed between them, wherein patch elements of the radiator circuit which are respectively disposed in each of slots made in the circuit are electromagnetically coupled to power supplying terminals of the both power supplying circuits rather than directly connecting them, whereby the radiator circuit and power supply terminals are freed from the necessity of direct connection between them as well as the impedance matching between them, so as to eventually improve the assembling ability to a large extent.