An apparatus 10 and method 30, 90 for imaging a tissue. The method includes transmitting a first microwave frequency signal to and receiving a first total signal from the tissue at a first position (Block 92). A second microwave frequency signal is transmitted to and a second total signal received from the tissue at a second position (Block 94). The first total signal is calibrated with respect to the second total signal (Block 104) and an image is constructed from the calibrated signal (Block 106).
