loss variables in particular the loss detector 107 is configured to ascertain the loss variables by a two port measurement by way of example the loss detector 107 comprises a network analyzer or a power detector furthermore the loss detector 107 is configured to ascertain in each case a forward transmission factor s 21 and an input reflection factor s ii in order to ascertain the loss variables here the loss detector will calculate the respective loss variable p loss by means of the following formula p loss 1 u2212 s 11 2 u2212 s 21 2 in particular the loss detector 107 is configured to establish the complex relative permittivity u2208 u2033 for ascertaining the respective loss variable to this end fig2 shows a diagram for illustrating the real relative permittivity u2208 u2032 and the complex relative permittivity u2208 u2033 depending on the frequency f here fig2 illustrates that the losses represented by the complex relative permittivity u2208 u2033 increase in the frequency range where the real part u2208 u2032 transitions from the higher level to the lower level this increase in the losses is also referred to as absorption lines in spectroscopy the effect that can be used in this case is that the frequency at which the excesses of the losses u2014 see local maximum of u2208 u2033 u2014 is displaced with the concentration of the sugar.