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.