ANTENNA SYSTEM

PURPOSE:To use an antenna both as the antenna of a lambda/2 type and the antenna of a lambda/4 type with one antenna element by matching input/output impedance automatically by connecting a matching coil to the antenna element at the time of the lambda/2 antenna length, and on the other hand, short-circuiting the matching coil at the time of the lambda/4 antenna length. CONSTITUTION:The length of the antenna element when it is extended becomes nearly as 1/2 times long as the wavelength lambda of an electromagnetic wave to be transmitted and received, and on the other hand when it is shortened, it becomes nearly as 1/4 times long as the wavelength lambda. The matching coil 11 is connected electrically to the antenna elements 1, 3 when extended to lambda/2 length to match the input/output impedance. On the other hand, when the antenna element is shortened to lambda/4 length, it is connected to the bottom part of a second rod 3 so that the matching coil 11 is short-circuited. Thus, characteristics specific to the antennae of the lambda/2 length and the lambda/4 length can be known by the single antenna element 1, 3.