DUAL BAND ANTENNA FOR MOBILE COMMUNICATION

摘要

A dual band antenna for mobile communications includes a rod-shaped radiating element (33) having a first portion of a predetermined length connected to a coaxial feed line (2), and a second portion of a specified length integrally extended from the first portion. The coaxial feed line connects to a ground plate (20) and a first capacitive load (37) connects to the first portion of the radiating element. A choke (35) surrounds the second portion of the radiating element, and has a shorting end connected to a distal end of the second portion and an open end at a proximal end of the second portion. A second capacitive load (36) connects to the shorting end of the choke. In a higher operating band of the dual band, the input impedance of the choke is high, such that only the first (lower) portion of the radiating element radiates. At a lower operating band of the dual band, the choke's input impedance is lower to allow for radiation from the entire length of the antenna.