Small-size dual-wideband IFA frame antenna closely integrated with metal casing of the LTE smartphone and having decreased user's hand effects

ABSTRACT A small‐size frame antenna based on the inverted‐F antenna (IFA) structure to cover 824∼960 and 1710∼2690 MHz for the LTE operation in the metal‐casing smartphone is presented. The antenna uses a short frame section of 53 mm (about 0.16 wavelength at 900 MHz) along the short edge of the metal casing as the IFA's radiating strip. The short frame section is closely integrated with the metal casing with a 2‐mm uniform gap and is easily fit within the short edge thereof. The frame section is connected to a feed circuit board (FCB), on which the IFA's shorting strip, feeding strip and matching network are disposed, to achieve the desired dual‐wideband operation. The FCB does not occupy the planar space on the metal casing and the system circuit board as well. In this regard, the occupied space of the antenna including the radiating frame section and the FCB in the smartphone is minimized. With the proposed antenna structure, effects of the user's hand on the antenna performance are also minimized, mainly because the small size of the antenna leads to no gaps along two long side edges of the metal‐casing smartphone. Details of the antenna structure and its working principle are addressed, and experimental results of the antenna are presented and discussed. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2853–2858, 2016