Communication terminal with casing conductors for reducing antenna gain degradation

摘要

An object of the invention is to provide a communication terminal capable of keeping the reception sensitivity good if the communication terminal is placed on a metal plate with the communication terminal laid on its side without the need for changing the size or the design of the main body of the communication terminal. A board (125) to which an antenna (107) is connected is provided inside a lower casing (105). The board (125) is provided with a GND plane to which a radiating element (121) is connected. An auxiliary bottom board (123) is joined to the radiating element (121) in a roughly perpendicular direction thereto. The radiating element (121) and the auxiliary bottom board (123) are conductors. A high-frequency current (131) flows into the board (125). Since a high-frequency current (133) of an opposite phase flows through a metal plate (141) because of the mirror image effect in a state in which the communication terminal is placed on the metal plate (141), the high-frequency current (131) is canceled and the radiation of the antenna (107) is weakened. However, the components perpendicular to the metal plate (141) do not cancel each other because of the mirror image effect and thus the radiating element (121) forms a dipole antenna symmetrically with the metal plate (141).