On‐frame gap‐coupled half‐loop antenna with a narrow ground clearance for the LTE smartphone

Abstract

ABSTRACTAn on‐frame gap‐coupled half‐loop antenna with a 3‐mm narrow ground clearance disposed at the short edge (bottom or top edge) of the modern LTE smartphone is presented. The antenna has two gap‐coupled half‐loops (first and second half‐loops) formed between an on‐frame metal strip and the device ground plane in the smartphone. The on‐frame metal strip comprises a first strip and a second strip and is disposed on the inner surface of the short‐edge frame of the smartphone casing. No extension of the on‐frame metal strip to two long side edges of the smartphone casing is needed. Two ends of the on‐frame metal strip are connected to the device ground plane through two inductors. Both the first and second strips are also gap‐coupled to a step‐shape feed strip disposed on the narrow ground clearance between the on‐frame metal strip and the device ground plane, thereby forming the first and second half‐loops. The two half‐loops are excited to contribute their fundamental and higher‐order resonant modes to form two operating bands to respectively cover the 824–960 and 1710–2690 MHz for the LTE operation. The antenna structure and operating principle are addressed in this study. Experimental results of the fabricated antenna are presented to verify the simulation study. Effects of the user's hand on the performance of the antenna are also analyzed. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2344–2351, 2016