This letter exploits a dual feature of rectangular open-ended ground slot to design an integrated 4G/5G antenna for mobile devices. In the proposed configuration, the antenna footprint of the 4G module is used for the installation of a 5G antenna module. While the entire rectangular slot is structured to operate at 800 MHz and 2 GHz, an array of 4-element Vivaldi antenna operating at 28 GHz is added within the slot space. This array provides end-fire radiation with 11 dBi peak realized gain. To validate the design concept, a prototype is fabricated on a RO-5880 substrate with an overall size of $150\times 75\times 0.51\text{ mm}^3$. The results show that the design covers two low frequency bands (from 770 to 810 MHz and from 1.9 to 2.6 GHz) with less than $-6$ dB reflection coefficient and a wideband millimeter-wave frequency range (from 26 to 32 GHz) with less than $-7$ dB reflection coefficient. A multiple-input–multiple-output (MIMO) configuration of the antenna is also realized with diversity performances verified.

中文翻译：

---

使用开放式插槽的混合天线，用于集成 4G/5G 移动应用

这封信利用矩形开放式接地槽的双重特性为移动设备设计了集成的 4G/5G 天线。在建议的配置中，4G 模块的天线覆盖区用于安装 5G 天线模块。虽然整个矩形槽的结构是在 800 MHz 和 2 GHz 下运行，但在槽空间内添加了一个 4 单元 Vivaldi 天线阵列，在 28 GHz 下运行。该阵列提供具有 11 dBi 峰值实现增益的端射辐射。为了验证设计概念，在 RO-5880 基板上制造了一个原型，整体尺寸为$150\times 75\times 0.51\text{ mm}^3$. 结果表明，该设计涵盖了两个低频段（从 770 到 810 MHz 和从 1.9 到 2.6 GHz），小于$-6$ dB 反射系数和宽带毫米波频率范围（从 26 到 32 GHz），小于 $-7$ dB 反射系数。还实现了天线的多输入多输出 (MIMO) 配置，并验证了分集性能。