Internal GSM/DCS antenna backed by a step-shaped ground plane for a PDA phone

A novel internal global system for mobile communication/digital communication system (GSM/DCS) antenna suitable for application in mobile devices such as the Personal Digital Assistant (PDA) phone is presented. The antenna has two radiating strips designed to operate at about 900 and 1800 MHz for GSM/DCS operation, and is backed by and short-circuited to a step-shaped ground plane. With the use of the step-shaped ground plane, which is to be placed at the top edge of the system ground plane of a PDA phone, the antenna can be employed in very close proximity to the possible RF shielding metal cases for battery and associated RF module/circuitry, with almost no degradation in the antenna performances. In addition, the antenna almost occupies no board space in the system ground plane, and is with a very small protruded length (3 mm only in this study) over the top edge of the system ground plane. The antenna is thus very promising to operate as an internal antenna, and in addition, shows an attractive electromagnetic compatibility (EMC) property with nearby conducting or RF elements inside a mobile device.