4G/Multiband handheld device ground antennas

Promising internal handheld device ground antennas are presented. Using the ground antenna concept, the antenna element functions mainly as an exciter and can have a very small size to achieve 4G/multiband operation. In this paper, ground antenna structures for handheld devices including the use of a loop strip, a half-loop strip, a simple shorted strip, or an inverted-F strip with the aid of a capacitive element to achieve decreased resonant length and the use of a small-size strip or patch with an inductive element to combine with the device ground plane to form as an asymmetric dipole structure are discussed. By aided with proper matching circuits, the ground antennas are promising to provide wideband operations. A small corner strip antenna with its resonant length 29 mm only (less than 0.08λ at 750 MHz) is also demonstrated for the LTE/WWAN tablet computer application. The ground antennas are also very promising to form high-isolation antenna systems for MIMO and diversity operation in the slim handheld devices.