Very-low-profile dual-wideband tablet computer antenna for LTE operation

A very-low-profile (8 mm in height), small-size (8 × 3 × 40 mm³), and dual-wideband loop antenna suitable for applications in the LTE tablet computer is presented. Dual-wideband operation is achieved using a wideband feed structure formed by a coupling feed, a high-pass matching circuit, and a tuning inductor. The coupling feed leads to successful excitation of a quarter-wavelength loop mode in the desired lower band. The high-pass matching circuit widens the low-band bandwidth to cover the 698~960 MHz band. The tuning inductor can adjust the frequency ratio of the first two higher-order loop modes to form a wide higher band to cover the 1710~2690 MHz band. Details of the proposed antenna are presented.