Compact Internal Antenna for Handheld Devices With Comprehensive DTV Band Coverage

A compact internal antenna design applicable to handheld digital TV receivers is proposed. Its operation bandwidth extends from 470 MHz to 860 MHz, which covers most terrestrial digital TV broadcasting bands. The antenna sizes protruding from the ground plane are 80 mm×15 mm×10 mm only and can fit in most palm-sized terminals. Major geometric features include a 3D folding structure that reduces the antenna footprint, a parasitic element that induces additional modes, and a folded microstrip line near the feed that improves the matching condition. The proposed design employs various methods to create multiple resonances in a confined antenna volume. Yet, a consistent radiation pattern is achieved over the operation band with decent efficiency performance. This is done by exciting several resonant modes within and adjacent to the desired band. Though the resonances take places at different antenna parts, most radiation comes from the current near the feed. The resulting antenna acts as a short electric dipole at all frequencies. Also, an abrupt efficiency roll-off is setup at the upper band limit to reduce interference from the nearby mobile service band. Rigorous studies were conducted to associate its superior performance features with implemented techniques.