To provide an inexpensive antenna system which uses a coaxial slot antenna by leading a flexible 2nd coaxial cable having a slot of specific wavelength at its upper part out of a 1st coaxial cable buried into the ground via a coupler and wiring the 2nd coaxial cable along a building.

An antenna system consists of a coaxial cable 2 which is buried into the ground and a coaxial cable 1 which is led out of the cable 2 via a coupler 6 and wired along the side face of a building such as a telephone box 20, etc., that is installed on the ground. The cable 1 is flexible and fixed to the box 20 via a fixing metallic parts 201. Furthermore, the cable 1 has a slot 11 of 1/2 wavelength at its upper part A and also has a dummy load (resistive terminator) 9 at the inside of its terminal part. In such a constitution, the antenna system functions as an antenna that has the sharp directivity owing to the slot 11 prepared at the part A. Then the antenna system can be produced at low cost and can be easily installed.