The device measuring a parameter p that depends on the real and/or imaginary parts of the permittivity of body tissue operates at a frequency f where a temperature change affects the permittivity of free water only weakly. If the parameter p depends on the real part of the permittivity only, the frequency f should be between 6.2 and 10.1 GHz. If the parameter p depends on the imaginary part of the permittivity only, the frequency f should be between 25.5 and 36 GHz. If parameter p depends on the real and imaginary parts of the permittivity, the derivative of the parameter in respect to the real and imaginary parts of permittivity can be used to calculate an optimum frequency range.
