Distributed systems robust to hand loading based on nonresonant elements

Miniature and multiband internal antenna systems are strongly required in emergent multifunction wireless devices. Recent techniques are focused on properly exciting ground plane radiation modes through nonresonant elements. These solutions remove the need of including quarter-wavelength resonant antennas featured by a considerable size. Nevertheless, in this new scenario, the complexity moves toward not only the reduction of the size of the elements used to excite the ground plane mode but also to the simplification of the radiofrequency system used to attain impedance matching. This article proposes the use of distributed systems based on nonresonant elements for solving the bandwidth and efficiency limitations of previous solutions while adding robustness to hand loading effects. Two different feeding schemes, an in-phase and an out-of-phase feeding scheme are simulated, measured, and compared in free-space as well as regarding the presence of a phantom hand. The proposal provides octo-band operation and attains a radiating system robust to hand loading effects capable of properly operating in nine communication standards, LTE700, GSM850, GSM900, DCS, PCS, UMTS, LTE2100, LTE2300, and LTE2500.