A compact dual-band antenna for portable wireless communications

We present a novel dual-band conformal antenna for use in portable wireless communication devices. Our design is based upon the wire inverted-F antenna (WIFA). The design employs two parallel closely-spaced WIFA elements embedded in the plastic case of the communications device. The WIFA elements are fed by a single microstrip transmission line located just above the grounding shell of the device. The microstrip line is oriented perpendicular to the WIFA elements and connected to a single coaxial cable feed that penetrates the grounding shell to reach the interior transmitter/receiver electronics. The length of each WIFA element is scaled according to the desired operating frequencies. This allows automatic operation of the antenna at two frequency bands simultaneously. Our conformal antenna design has a small footprint. We apply our design to Motorola´s StarTac(R) cellular phone and demonstrate that the new antenna design provides a good radiation performance and bandwidth along with flexible positioning on the surface of the StarTac(R). We use FDTD modeling to obtain results for the voltage standing-wave ratio and radiation patterns.