The present invention proposes a direct receiver technique based on one power measurement and time multiplexing of input signals. The proposed technique allows I/Q demodulation. The proposed technique bases on the passive linear three-port high frequency circuitry (1) having two RF signal input (2, 5) and one output port (3) attached to a power sensor (4). The signals output from the power sensor (4) is low pass filtered (17) and supplied to a DC interface. The proposed linear three-port circuitry (1) contains at least one RF switch and at least one passive circuit having at least one phase shifter functionality.