A small tunable antenna using multiple shorting posts and varactor diodes

An electrically small tunable antenna for use in mobile terminals is designed. The small size of the antenna is achieved by the use of multiple shorting posts and varactor diodes. Multiple shorting posts are used to allow a greater freedom in the placement of the probe feed. Two varactor diodes placed in line with the shorting posts are used to further decrease the size of the antenna. The antenna can be tuned over a range from 0.55GHz to 1.5GHz. However the antenna has a small gain at the lower frequencies due to its small size.