An apparatus for detecting skin cancer using THz radiation, for irradiating a sample (19) with transmission THz radiation (18) and for evaluating reception THz radiation (25) coming from the sample has: a high-frequency source (11, 41) for generating a high-frequency signal for use in a transmission branch (13, 43) and a reception branch (14, 44), a power splitter (15, 45) for dividing the high-frequency signal between the transmission branch and the reception branch a first frequency multiplier for multiplying the frequency of the high-frequency signal and a transmission antenna for emitting the frequency-multiplied high-frequency signal as transmission THz radiation in the transmission branch (13, 43) a frequency generator (21, 51) for generating a low-frequency signal, a mixer (20, 50) for mixing the high-frequency signal with the low-frequency signal in order to generate a reception branch mixed-frequency signal, a second frequency multiplier (23, 53) for multiplying the reception branch mixed frequency, a reception antenna device (31, 54) for receiving the reception THz radiation (25) and for generating a THz signal, a mixing device (29, 59) for mixing the THz signal with the frequency-multiplied reception branch mixed-frequency signal in order to generate a measurement signal and an evaluation device (30, 63) for evaluating the measurement signal in the reception branch (14, 44).
