At least 2 provides two functionally independent radar level gauging system (1) for determining the filling level of the product 9 contained in the tank by transmitting and receiving the microwave signal on the channel. Each channel transceiver circuit device (31, 32 to the basis of a relationship between the received and printed circuit of the transceiver circuit device (31, 32) and the transmission signal array on the substrate (34) signals to determine the charge level ) processing circuitry (having an electronic unit (3a, 3b) having a 33), each electronic unit (3a) connected to is electronically and no ribs electrically isolated from the other electronic unit (3b). The system also includes a hollow wave guide (5) for guiding a microwave signal between a single antenna 4 and each transceiver circuitry and an antenna for emitting a microwave signal into the tank. Each electronic unit further comprising a supply circuit elements arranged on a printed circuit board, the supply circuit element includes at least one of the feed probe 36, which protrudes into the waveguide to feed said microwave signal in the waveguide . The invention enables a very simple, efficient and reliable supply for each channel, which in terms of cost.