Reconfigurable resonant module for multi-band antenna design

Novel resonant modules for constructing multi-band mobile antennas are proposed in this study. The basic configuration of the module, named as the prototype module, is designed based on a series LC resonant circuit. By adding a varactor to the module, it can be transformed into a reconfigurable module. By introducing an extra resonant mode with capacitive coupling to enhance the bandwidth, a wide-band module can be obtained. These modules have different frequency ranges, and can be combined into multi-band antennas for various applications. The proposed modules are demonstrated by constructing a 4G-LTE antenna. The reconfigurable module, which is of 20 × 20 mm2, is designed to switch between LTE700 (698–787 MHz) and GSM850 (824–960 MHz) bands. The wide-band module, which is of 10 × 10 mm2 and 49.3% bandwidth, is designed for GSM1800/GSM1900/UMTS/LTE2300/LTE2500 (1.71–2.59 GHz) applications. All designs have been realised and measured for validation. The proposed antenna modules, which are simple and convenient to use, can provide flexibility, especially in antenna deployment, in multi-band mobile antenna designs.