The invention relates to a device for treating soil with electromagnetic radiation, comprising: - a magnetron antenna (9) for generating microwave radiation with a relatively high frequency； a wave guide (16) connected to the output of the magnetron antenna (9)； downward directed tubular members (18, 19) connected to the wave guide (16)； -a manifold (17) arranged between the two tubular members (18, 19) and the wave guide (16)； - a tuner unit (26) arranged on the wave guide (16)； and - cooling means (22, 22', 22'') for cooling the electromagnetic radiation reflected by the soil. The invention also relates to a cable (24) provided with a single high-voltage cable and one or more low-voltage cables and/or a number of optical cables which are arranged in a shared cable. The invention finally relates to a method for disinfecting soil, wherein a magnetron (9) placed on a vehicle is moved over the soil, wherein the radiation reflected by the soil is minimized by tuning the wave guide (16) connected to the magnetron (9), and wherein the minimized reflected radiation is absorbed by a water load which is connected to one or two water tanks (22', 22'') which are placed on the vehicle and which hold the temperature of the water within predetermined limits.
