離子高分子金屬複合材料應用在雙頻性天線與可靠性之研究

Abstract

在文中我們將會探討離子聚合物金屬複合材料作為射頻切換開關的應用。利用離子聚合物金屬複合材料作為制動器控制一金屬片，連結或斷開天線與一延伸段，進而改變天線的接收頻率，設計成一組雙頻性天線。此複合材料有諸多優點如重量輕、體積小、成本低、驅動電壓低……等，特別是在於驅動電壓只需約3伏特左右，故適合應用在可攜式裝置上。 我們將此雙頻性天線結構設計於手機裝置中，在施加驅動電壓前，制動器平躺並使金屬片貼服兩天線段，工作頻率為1.07GHz；當驅動電壓施加至3伏特，制動器產生形變使金屬片離開兩天線段，工作頻率升至2.14GHz，反射損失皆低於-10dB。為了改善電解與在空氣中的使用時間等問題，我們利用碳酸丙烯酯作為電解液並加入過氯酸鋰取代原先的氫氧化鋰水溶液。結果在操作電壓3.5伏特下，離子聚合物金屬複合材料可在空氣中致動超過三個月且致動位移量並未明顯減弱。因此，離子聚合物金屬複合材料應用在雙頻性天線上是可行的且充滿潛力。

In this research, a new application of electro-active-polymer for RF (radio frequency) switch is presented. We used an ionic polymer metallic composite (IPMC) switch to change operating frequency of inverted-F antenna. This switch has attractive advantages, such as light weight, small volume and low cost. Especially, driving voltage of 3 volts and thickness of 200 μm make IPMC be suitable for mobile devices. IPMC acts as a normally-on switch to control the operating frequency of reconfigurable antenna in mobile phones. We experimentally demonstrated that an IPMC switch can shift operating frequency from 1.1 GHz to 2.1 GHz with both return losses less than -10 dB under network analysis. To minimize electrolysis and maximize operation time in air, the propylene carbonate electrolyte with Lithium perchlorate (LiClO4) was applied inside IPMC. The results show that IPMC can be actuated over three months in 3.5 V and tip displacement is decreased less than 10%. Therefore, an IPMC actuator is a promising solution for the reconfigurable antenna application.