Improvement of ground radiation antenna performance using compact EBG in presence of battery effects

Abstract

In Internet-of-things devices. to alleviate the performance degradation of the ground radiation antenna due to the large battery. two compact electromagnetic bandgap (El%) unit cells are introduced between the ground radiation antenna and the battery. The ground radiation antenna is comprised a small loop-type circuit that is designed within a 5-mm x 5-mm ground clearance for 2.4-GHz Vv'LAN applications. The compact ERG unit cell is a modified square split-ring resonator that is designed by meandering-line technology. The measurement results showed that the 3:1 VSWR impedance bandwidth of the ground radiation antenna increased from 30 to 90 MHz, and the average total efficiency increased from 19% to over 54% with and without the introduction of the ERG structure, respectively.