PURPOSE: To prevent a positive polarization pattern and the identification degree of a cross polarization wave from being deteriorated, by providing a print dipole antenna and a slot line formed with a metallic foil on the front side of a dielectric substrate, and providing a microstrip line, a dielectric honeycomb core having thickness of almost 1/4-wave on the rear side and a metallic plate on the outer plane.

CONSTITUTION: The dielecric honeycomb core 18 having the thickness L of around 1/4λ and the metallic plate 19 are bonded under the metallic foil 17 at a part corresponding to the rear side of the print dipole antenna 13. The metallic plate 19 performs the role of a reflecting plate for the print dipole antenna 13. And the dielectric constant of the dielectric honeycomb core is set by using a material with low constant of around 1.1∼1.2. An electromagnetic wave transmitted on the microstrip line where the metallic foil 12 is set as a ground conductor excites the slot line 14 at a coupling part 16. At this time, since the line 15 is covered with the metallic foil 12 and the metallic plate 19, it is possible to prevent an unrequired radiant wave from the line 15 from being leaked to the outside including the radiating direction D of the antenna.