To obtain an antenna system with enhanced work efficiency as to the layout position of the dielectric strip or the like and a stable characteristic against a temperature change.

The antenna system 10 comprises two conductor plates 11, 12 that are placed nearly in parallel to each other, a dielectric strip 13 that is interposed between the conductor plates 11, 12, an opening 14 that is provided on the upper conductor plate 11 and over the dielectric strip 13, and a matching section 20 that matches the impedance of the dielectric strip 13 with that of the opening 14. Since the matching section 20 is integrated with the dielectric strip 13 under the opening 14, they are laid out in connection with each other.