物聯(lián)網(wǎng)和移動設(shè)備的天線選項

　　天線（被稱為“天線”在某些國家）是第一個組成部分，在接收器射頻信號鏈和最后一個在發(fā)射鏈。雖然在概念上是一個簡單的能量轉(zhuǎn)換器之間的電壓/電流在電路和相應(yīng)的電磁場（EM）領(lǐng)域輻射到或從空間，有許多執(zhí)行問題與此基本的無源元件。

　　天線基本理論覆蓋了許多書籍，文章和網(wǎng)站（三應(yīng)用筆記LINX技術(shù)是特別有用的1，2，3）。今天的天線用戶和設(shè)計師也使用強大的和相當(dāng)準(zhǔn)確的軟件工具，模型的天線和相關(guān)的電磁場。這些允許詳細(xì)的模擬天線的“自由場”的特點，以及它的性能在最終產(chǎn)品和安裝，天線本質(zhì)上與他們周圍的環(huán)境互動。這些工具是特別重要的PC板的設(shè)計，其中的天線和其余的電路是在接近。

　　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.