An apparatus for making resistivity measurements near a drill bit includes a tool body, a transmitter deployed on the tool body, a receiver deployed on the tool body and at an axial distance from the transmitter, and a transmitting signal coupler coupled to the transmitter antenna and the receiver. The transmitter generates electrical signals and converts the electrical signals into electromagnetic signals to be transmitted. The receiver measures the amplitudes and phases of the electromagnetic signals received from the transmitter. The transmitting signal coupler couples a portion of the electrical signals from the transmitter antenna and measures the amplitudes and phases of the coupled electrical signals. Amplitude attenuation and phase shift between the electromagnetic signals received at the receiver and the electrical signals coupled at the transmitting signal coupler are computed for calculating resistivity.