The measurement device comprises a transmitter (20) for providing a transmitted signal at a frequency. The transmitter provides the transmitted signal to the transmitting antenna (20).A receiving antenna (28) is arranged to receive the transmitted signal. A receiver (26) is capable of receiving the transmitted signal from the receiving antenna. An electronic data processor (38) is adapted to measure an observed parameter of the transmitted signal between the transmitting antenna and the receiving antenna to estimate the precise yield, where the observed parameter comprises observed attenuation, phase or both of the transmitted signal, as received at the receiver.
