PURPOSE: To improve the manufacturing technology, to increase the degree of coupling and to reduce the adverse effect of a feeder onto an antenna characteristic by adopting a coplaner line for the feeding system and locating the coplaner line to a face different from that of a microstrip antenna.

CONSTITUTION: The antenna consists of a microstrip antenna 1, a feeder line 2 as a component of the coplaner line, a GND face 3 in existence on the same plane as that of the feeder 2 and a base 4. An electromagnetic wave propagated onto the coplaner line comprising the feeder 2, the GND plane 3 and the base 4 is coupled with the microstrip antenna 1 above the coplaner line electromagnetically via an offset with a length of (d). Then the electromagnetic wave from the microstrip antenna is radiated. Thus, a high degree of coupling is realized without requiring any highly accurate manufacturing technology and the effect of the feeder onto the antenna characteristic is reduced.