A triple-band internal antenna: design and performance in presence of the handset case, battery, and human head

An internal triple-band antenna fed by a microstrip line is proposed for operating at PCS, IMT-2000, and Bluetooth bands. As a starting point, a two-branch meander-line antenna is used to achieve the desired resonant frequency. A broadband characteristic for each band can be optimized by tuning the parts of radiating meander lines and size of each strip line segment. Considering normal use situation, the initially designed structure of the proposed antenna is extended and modified to tune the desired frequency bandwidth on the placement of handset case and battery, and in the presence of the head. Detailed model of the handset case is implemented to check the effects of the phone case and battery on the antenna performance. The return loss and radiation patterns from the proposed antenna built in a phone case in the presence of the phantom head are presented. It is found that the battery and human head have a strong influence on the antenna input impedance, radiation patterns, and gain for the internal antenna configurations. The computational values are presented to validate the experimental results.