说明：  The rapid and accurate assessment of burn injuries is a very challenging task in burn surgery. To illustrate the potential of millimeter-wave systems for burn diagnosis, the current paper at first shows a coaxial probe based ex-vivo measurement of the effective relative permittivity of skin depending on the degree of burn and also in-vivo measurements of the relative permittivity change caused by small skin irritation (i.e., increased or decreased blood perfusion, edema formation) in the frequency range 0.1 to 50 GHz. Based on the presented relation between skin condition, frequency, permittivity and loss, a MIMO-SAR imaging system operating at 75 GHz