A new directional antenna for ISM applications

The design and analysis of a new directional antenna is presented. This antenna can be used in a hand-held device or instruments requiring an antenna radiating in a particular direction. The antenna has a small size, and can be built on a single or double sided printed circuit board. It can also be built as a on-board antenna to reduce manufacturing cost. The antenna presented consists of two dipoles. The two dipoles are placed in parallel and very close to each other. The antenna has a radiation pattern very similar to that of a two element Yagi antenna having one driven element and one director, a front-to-back ratio more than 10 dB, and a gain more than 3 dBd. No matching network is required since the antenna is designed for a 50 ohms input impedance at the center frequency of a band. The method of moments, particularly, the reaction technique, is used for the analysis