Theoretical and experimental investigation on dynamic active antenna

This paper discusses theoretical and experimental investigation, on dynamic active antenna which can detect the contact point between an insensitive flexible beam and an object through estimation of the oscillation frequency in contact with the object. We first prove that the contact position is uniquely determined if we consider every mode of natural frequencies of the beam in contact with the object, while the fundamental and the second order natural frequency, in most cases, satisfy the sufficient condition for providing the unique contact position. We also show a desirable mass distribution avoiding the estimation error for localizing the contact position. By utilising the maximum entropy method, we succeeded in experimental estimating the contact point from the fundamental and the second order natural frequencies.