Design of Compact Differential Dual-Frequency Antenna With Stacked Patches

Abstract

A compact differential dual-frequency antenna with stacked configuration is described. Compared with the conventional stacked dual frequency antenna, the radiating element with a half guided wavelength is distributed on two layers and connected through via holes, thus the dimension of the antenna is reduced effectively. In order to improve the bandwidth at the first resonant frequency (f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> ), a reflecting board is introduced and connected with the ground plane through three via holes. As a result, a new resonant frequency closing to f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> can be excited and the bandwidth at fx is enhanced. Both differential antennas with and without the reflecting board are fabricated and measured. The realized antennas have a compact size of 15 mm × 15 mm, which equals to 0.23¿ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> × 0.23¿ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> (¿ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> , the guided wavelength at f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> ). Experimental results show that the proposed antenna can operate at 2.4 GHz and 5.2 GHz bands. Good agreement between the simulated and measured results is obtained.