基於全金屬網格結構之輕量化寬頻天線設計及其多物理場分析

Abstract

本論文提出了兩款專為輕量化和寬頻應用而設計的具有網格結構之全金屬天線。針對特定的應用情境，我們分別說明了天線的設計流程、工作原理以及原型製作與測試結果。在分析中，除了基本的電磁性能之外，還進行多物理場探討。 第一款設計是專為低地球軌道(LEO)到地球靜止軌道(GEO)衛星間鏈路設計的具有寬頻（1.8-2.3 GHz）圓極化之輕量化堆疊式貼片天線。該天線由四個網格狀薄鋁圓盤組成，設計中未使用任何介質基板，僅採用聚醯胺墊片支撐這四個鋁圓盤，旨在避免基板中熱量蓄積，並減輕天線的重量。此外，採用新穎的同心圓網狀結構，不僅確保了天線效能和結構牢固性，更重要的是天線重量（僅30公克）減輕一半。其寬頻圓極化特性是透過循序旋轉饋入方式和堆疊式貼片結構實現。多物理場分析顯示，所提出的天線能有效適應火箭發射時惡劣的震動環境。隨機振動分析確保了結構可靠性。天線原型以電腦數值控制（CNC）金屬加工技術製作並測試，測量結果符合衛星間鏈路應用規格。 第二款設計是專為高功率機載應用所設計的具有寬頻（2.9-3.5 GHz）線性極化之超輕量化折疊E形貼片天線。該天線僅由折疊的E形貼片和接地面組成，它們均由鋁網製成。在它們之間的支撐採用了聚醯胺墊片，以取代介質基板，這對天線的重量和熱量蓄積皆有顯著的降低。本設計（小於1公克）在重量方面大幅減少了90.34%，這可歸功於天線的小型化和全金屬網格設計。天線的寬頻性能是透過E形貼片激發的兩個鄰近的諧振實現。高功率分析顯示，這種全金屬網格狀設計不僅具備足夠的功率處理能力(3.4x10^6瓦)，還能在75瓦連續波的輸入功率下將天線結構的溫度維持在可接受範圍(45.54°C)。天線的隨機振動分析確認其結構穩定性。天線原型以金屬3D列印製作，量測結果符合高功率S波段應用預期。

This dissertation presents two novel all-metal antennas with mesh structures specifically designed for lightweight and broadband applications. For specific application scenarios, we systematically illustrate the antenna design process, working principles, and prototype fabrication and testing. In the analysis, beyond the fundamental electromagnetic performance, multi-physics investigations are also conducted. The first design is a lightweight stacked patch antenna with broadband (1.8-2.3 GHz) circular polarization designed for Low Earth Orbit (LEO) to Geostationary Orbit (GEO) satellite links. The antenna comprises a structure of four thin meshed aluminum disks supported by polyamide spacers instead of dielectric substrates. This design aims to avoid heat accumulation in the substrate and reduce the antenna's weight. Furthermore, adopting a novel concentric circular mesh structure ensures undegraded antenna performance and structural robustness and, more importantly, reduces the antenna weight by half (only 30 g). The broadband circular polarization characteristic is achieved through a sequential rotation feed structure and a stacked patch topology. Multi-physics analysis demonstrates that the proposed antenna can effectively adapt to the harsh vibrating environments in the launch vehicles. Random vibration analysis confirms the structural reliability. A prototype antenna was fabricated using Computer Numerical Control (CNC) metal processing and tested, with measurement results meeting the specifications for LEO-to-GEO inter-satellite link applications. The second design is a lightweight folded E-shaped patch antenna with wideband (2.9-3.5 GHz) linear polarization designed for high-power airborne applications. The antenna consists solely of a folded E-shaped patch and a ground plane, both made of aluminum mesh. Polyamide spacers are used for support between them, eliminating the need for a dielectric substrate, which significantly reduces both the antenna's weight and heat accumulation. This design (less than 1 g) achieves an impressive 90.34% weight reduction, attributed to the antenna's miniaturization and the metal's meshed design. The wideband performance is achieved through the two adjacent resonances excited by the E-shaped patch. In the high-power analysis, this all-mesh design not only possesses sufficient power handling capability of 3.4x10^6 W but also maintains its temperature within an acceptable range of 45.54°C under a continuous wave input power of 75 W. The antenna's vibrations are analyzed, confirming structural stability. An antenna prototype is fabricated using metal 3D printing, and the measured results meet the expectations for high-power S-band applications.