寬頻微波擷取技術---子計畫四：建立ADI-FDTD模擬平台探討後設物質於行動裝置應用

Abstract

隨著個人行動通訊產品普遍使用，造成人體暴露於電磁環境中。大眾逐漸關心電磁波對於人體的影響。在常用通訊產品中，由於手機使用時最接近人體，也因此最受重視。一般手機電磁規範，主要是量測特定吸收效率值(SAR)，藉而得知人體組織所吸收電磁輻射強度。另一方面，許多研究利用時域有限差分法並結合人頭模型，可以有效準確預測人體特定吸收效率值。 最近，後設材質(Metamaterials)的電磁特性引起廣大興趣。其電磁特性不同於一般自然界常見的物質。藉由適當週期性排列細金屬片以及分離式環形共振器，可使物質的介電係數(u)與導磁係數(ε)為負值，目前後設材質已引起廣泛研究並應用於許多高頻電路中。 在本計畫中，第一年將建立人頭電磁模擬環境，包括電磁數值模擬平台建立並將人頭模型整合入模擬平台。並發展無條件穩定時域有限差分法以加快運算時間。在第二年中，將藉由後設材質的電磁特性，應用於行動通訊產品以減低對於人體特定吸收效率。我們將建立後設材質電磁模擬方法，以瞭解其物理與電磁特性。藉由適當設計後設材質置於行動通訊設備，藉此觀察減低人體特定吸收效率的成效。第三年藉由電磁數值模擬方法提出對於總計畫系統整合電磁效應可能改善方法。

The penetration rate of the mobile devices has been growing rapidly in the global communities. The influence of EM waves from cellular phones has been widely discussed recently. The specific absorbing rate (SAR) is a defined parameter for evaluating power deposition in human tissue. The finite-difference time-domain (FDTD) is used widely to study the peak SAR in the human head. Recently, metamaterials have inspired great interests in their unique physical properties and novel application. Metamaterials denote artificially constructed materials having electromagnetic properties not general found in nature. Two important parameters, electric permittivity and magnetic permeability determine the response of the materials to the electromagnetic propagation. In recent years, metamaterials are studied and applied on the microwave devices. In this project, during first year, we will set up the FDTD platform to study the SAR in the human head. The human head model will be incorporated into this simulation environment. We will develop the ADI-FDTD method to speed up the simulation time. During the second year, we will setup the numerical method to understand the physical and electromagnetic properties of metamaterials. We will design the metamaterials to reduce the EM interaction between portable telephone and human head. During the third year, the electromagnetic characteristics of the integration system will be studied by the developed numerical method. From simulation, we can provide some methods to improve the electromagnetic performance in the integration system.