In this article, a compact low-profile antenna for octa-band unbroken metal-rimmed smartphone applications is proposed. The antenna consists of a capacitive coupling rectangular vertical plate and two new-type extended ground branches. For lower frequency, the LTE700, GSM850, and GSM900 bands are provided by the bezel mode which is generated through capacitive coupling excitation of a rectangular vertical plate to the bezel. For upper frequency, the DCS, PCS, UMTS, LTE2300 and LTE2500 bands are covered by the multiple modes of two ground branches. With the proposed structure, the operating bands can be expanded and optimized simply. All the mentioned bands are achieved in the size of ( $70 \times 7 + 20 \times 2$ ) $\times $ (1.5 + 0.8) mm³ on the 130 mm $\times \,\, 70$ mm system board. The antenna is fabricated and measured to verify this proposal. The tested results include reflection coefficient, radiation patterns, efficiency, and gain.

中文翻译：

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用于八频段金属边框移动电话应用的薄型紧凑型天线

在本文中，提出了一种适用于八频段不间断金属边框智能手机应用的紧凑型低剖面天线。该天线由一个电容耦合矩形垂直板和两个新型扩展接地支路组成。对于低频，LTE700、GSM850 和 GSM900 频段由边框模式提供，边框模式是通过矩形垂直板对边框的电容耦合激励产生的。对于高频，DCS、PCS、UMTS、LTE2300和LTE2500频段由两个地面支路的多模覆盖。通过所提出的结构，可以简单地扩展和优化工作频带。所有提到的波段都是在 ( $70 \times 7 + 20 \times 2$ ) $\times $ (1.5 + 0.8) 毫米³上 130 毫米 $\times \,\, 70$ 毫米系统板。天线被制造和测量以验证这个提议。测试结果包括反射系数、辐射模式、效率和增益。