物联网和移动设备的天线选项

　　物联网和移动设备的天线选项

　　天线（被称为“天线”在某些国家）是第一个组成部分，在接收器射频信号链和最后一个在发射链。虽然在概念上是一个简单的能量转换器之间的电压/电流在电路和相应的电磁场（EM）领域辐射到或从空间，有许多执行问题与此基本的无源元件。

　　天线基本理论覆盖了许多书籍，文章和网站（三应用笔记LINX技术是特别有用的1，2，3）。今天的天线用户和设计师也使用强大的和相当准确的软件工具，模型的天线和相关的电磁场。这些允许详细的模拟天线的“自由场”的特点，以及它的性能在最终产品和安装，天线本质上与他们周围的环境互动。这些工具是特别重要的PC板的设计，其中的天线和其余的电路是在接近。

　　Further， the growth of small， low-power wireless devices， such as for the Internet of Things （IoT） and handheld/portable devices， has placed new performance mandates on operating frequency， bandwidth， size， physical design， and radiation pattern/directivity/gain of this “unglamorous” component. Designers can choose among many fundamental antenna types， including external longwire， short whip， PC-board fabrication， ceramic chip， and proprietary （custom-designed） styles. The whip， PC-board， and ceramic-chip antennas are the most practical choices for IoT and mobile devices operating in the GHz region.

　　The whip antenna is an external discrete component， usually up to about 2 to 4 inches （5 to 10 cm） long at these frequencies. It offers well-defined， self-contained performance specifications which are largely independent of the transmitter/receiver itself. The whip can be attached directly to the PC board via a board-mounted connector， or located nearby and connected via a coax cable. While both the coax cable and PC-board connector add cost in addition to the antenna itself， this arrangement allows flexibility in PC-board design as well as end-product packaging and installation.