A Compact and Low-Profile Loop Antenna With Multiband Operation for Ultra-Thin Smartphones

Abstract

A folded loop antenna having a very compact size of 5 × 8 × 60 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> with multiband operation for ultra-thin smartphone applications is proposed. The antenna generates four resonant modes, the traditional 0.5-λ, 1-λ, and 1.5-λ resonant modes and an extra higherorder 2-λ resonant mode, to cover the GSM850, GSM900, DCS1800, PCS1900, UMTS, TD-SCDMA, LTE2300, and WLAN systems. The extra 2-λ resonant mode is generated using a certain distance between the feed point and the shorting point on the ground plane. The antenna is studied using simulation and measurement. To study the antenna in a more realistic situation, a standard metallic USB connector is placed inside the loop radiator. Results show that the USB connector has little effects on the antenna performance.