基於端射架構之太赫茲頻段前視輻射天線封裝設計以緩解空間限制

Abstract

在無線通信領域，日益增長的數據流量和多樣化的服務需求對現有的頻譜資源提出了嚴峻挑戰。為了滿足不斷擴大的通信需求，人們開始探索新的高頻頻段，其中毫米波(mmWave)和太赫茲(THz)頻段被認為是很有前景的候選方案[1][2]。這一頻段的優勢在於能夠滿足高頻寬與低延遲的通訊需求，應對不斷增長的數據流量需求。與目前的通信技術相比，次太赫茲(sub-THz)介於上述兩波段之間，其具有高頻譜效率和低功耗的特性，為物聯網、虛擬實境等新興應用提供了強大的技術基礎。 然而，該頻段的應用面臨挑戰，包括高頻電磁波的傳播損耗和有限的傳輸距離，這使得其覆蓋範圍受到限制。大規模相控陣列天線被視為應對這些問題的有效解決方案。這種天線通過電子控制快速調整波束方向，不僅提升了增益，也拓展了覆蓋範圍。但sub-THz的短波長為天線的設計與製造帶來了挑戰。傳統的天線結構通常依賴多層PCB基板，將THz相控晶片安裝在PCB底層，或與天線置於同一平面。由於THz相控晶片的尺寸相對天線過大，這些方式在高頻應用中面臨局限。 我們提出了一種新型的AiP(antenna-in-package)設計，採用end-fire輻射方式，將天線元件設置於基板邊緣，使其輻射方向平行於基板，從而在天線後部保留充足空間以安裝THz相控晶片和其他相關電路。具體設計中，我們利用多層一維(1-D)end-fire陣列進行垂直堆疊，構建出二維(2-D)陣列架構。這些一維陣列具備雙極化特性，能實現與基站天線的極化匹配，並預留空間安置THz相控晶片。為了完成垂直堆疊，我們採用了厚度超過THz IC的dummy wafer柱，將多個一維子陣列面板組合成二維AiP陣列。最終，天線旋轉90度，使輻射模式從end-fire轉為broadside，減少了整體佔用空間。目前，我們已完成1x4天線的模擬與測量驗證，並完成4x4陣列天線的模擬分析。同時，我們也確定了未來需要採用的封裝技術，以實現1x4陣列的等間距垂直堆疊。

In wireless communications, the growing demand for data traffic challenges existing spectrum resources. Researchers are now exploring high-frequency bands, specifically millimeter-wave (mmWave) and Terahertz (THz) bands, which offer high bandwidth and low latency and address these needs. The sub-THz band, in particular, provides higher spectral efficiency and lower power consumption, supporting emerging applications like the Internet of Things (IoT) and virtual reality (VR). However, these high-frequency bands face challenges, including significant propagation losses and limited transmission distances that restrict coverage. Large-scale phased-array antennas can help by electronically steering beams to enhance gain and extend coverage. Yet, traditional antenna designs using multi-layer printed circuit boards (PCBs) encounter limitations because THz transceiver modules are often larger than the antennas. To overcome these issues, we propose an Antenna-in-Package (AiP) design that positions the antenna elements at the edge of the substrate, directing radiation parallel to it. This design uses vertically stacked one-dimensional End-Fire arrays to create a two-dimensional array. These arrays feature dual-polarization capabilities, aligning with base station antennas while allowing space for THZ transceiver modules. We achieve vertical stacking with connectors thicker than THz integrated circuits, leading to a compact 2-D AiP array. Additionally, the antenna is rotated 90 degrees, transforming the radiation mode and reducing its overall footprint. We have completed simulations and measurements of a 1x4 antenna and analyzed a 4x4 array antenna, as well as identified the necessary packaging technology for vertical stacking of 1x4 arrays.