ELEMENT LENGTH DETECTOR, MATCHING CIRCUIT AND RADIO TERMINAL

摘要

PROBLEM TO BE SOLVED: To relax restriction of mount in a case and to detect elongation/ contraction of an antenna element with high precision at a low cost with respect to an element length detector that detects the length of the telescopic antenna element and a matching circuit and a radio terminal that employ the element length detector. SOLUTION: The element length detector is provided with a coil 13 that is wound on an outer face of a chamber 12 formed to be a tube or a cylinder to which all or part of an element 11 of an antenna 10 displaced in response to the telescopic motion of the antenna 10 is contained and with a contained element monitor means 14 that monitors the polarity of an electromotive force induced in the coil 13 in response to the display of the element 11 in the telescopic process of the antenna 10 and obtains a position of the element 11 with respect to a part of the outer side face on which the coil 13 is wound.