在本計畫中，預計將以一年的時程，設計一個操作頻率28 GH由5個圓極化天線所組成之串聯式天線陣列。在網格天線(grid antenna)工作原理的基礎下，預計將兩個互相垂直的網格元素(element)藉由耦合方式，完成圓極化的輻射，此想法在本計劃的先期模擬結果中，顯示其具有可行性。陣列元素間間隔一波導波長，使每個幅射元件可同相輻射，且可降低傳輸線造成的輻射影響，並設計在尾端使用單埠天線輻射電阻(radiation resistance)取代行匹配電阻，不使用實際電阻，達成較高效率。在進一歩的計劃執行中，將利用步階阻抗諧振腔(Stepped-Impedance Resonator，SIR)來取代原網格元素，以達成增加阻抗頻寛的目的。此外，為了加強軸比(axial ratio)頻寛，在陣列的佈局上，將考慮採用文獻[12]的技術。預計其最大增益>15dBic，極化差>15dB，阻抗頻寬>3%，3dB軸比頻寬(axial ratio)>3%。天線陣列的設計結果將採用國研院國家晶片中心的PCB製程來實現，並加以量測以驗証設計的正確性。 ;In the project, a 28-GHz circularly-polarized grid antenna array with 5 elements will be designed and manufactured. The element is composed of two mutually orthogonal strip resonators and a coupling structure. While two resonators provide two radiation fields which are orthogonal to each other, the coupling structure provides the required 90-degree phase difference resulting in the circularly-polarized radiation. Preliminary has been conducted, and the simulated results shows the high feasibility of the project. In the further part of the project, stepped-impedance resonator will be applied to replace the strip resonator to achieve impedance bandwidth enhancement. Also, the technique reported in [12] will be adopted in the array deployment to obtain wider axial-ratio bandwidth. The expected specifications of the proposed design are as follows: peak gain > 15dBic, (left-hand cpl)/(right-hand cpl) > 15dB, impedance bandwidth > 3%, and axial ratio bandwidth > 3%. The proposed antenna array will be realized and measured by using CIC facility for design validation.
