Study and design of a capacitively coupled polymeric internal antenna

A capacitively coupled polymeric internal antenna is introduced for Bluetooth or GPS applications. Such an antenna can be easily fabricated on a flexible film substrate and attached to the inside surface of the plastic housing of a portable wireless device, such as a PDA. The proposed antenna saves critical space on the printed circuit board (PCB) and eliminates the need for a vertical contact feed. Thus manufacturing is also simplified and cost is reduced. Practical examples of utilizing such a concept for Bluetooth (2.45 GHz) and GPS (1.575 GHz) applications are provided. The antenna system requires a small coupling plate (as small as 4 by 4 mm²) that can be easily surface mounted on a PCB. The solution proposed provides wideband operation satisfying Bluetooth functionality with good radiation pattern and gain.