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

In Internet‐of‐things devices, to alleviate the performance degradation of the ground radiation antenna due to the large battery, two compact electromagnetic bandgap (EBG) 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 × 5‐mm ground clearance for 2.4‐GHz WLAN applications. The compact EBG 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 EBG structure, respectively. [ABSTRACT FROM AUTHOR]