An Endfire Vertical Polarized Antenna-in-Package and Wide-angle Scanning Phase Array Antenna

This article presents a novel millimeter-wave (mmWave) endfire vertically polarized (VP) antenna-in-package (AiP) with a compact size and a $1 \times 8$-element wide-angle scanning phased array antenna (PAA). The VP element is implemented using an open-end cavity antenna. The design process of the lowprofile VP element, transformed from a patch antenna, is demonstrated in detail. Additionally, slots are incorporated into the element to achieve a wider bandwidth and a higher front-to-back ratio (FBR). Subsequently, a $1 \times 8$-element PAA is designed based on the proposed element. To meet integration requirements and facilitate chip interconnection for AiP, the proposed antenna is fabricated using low-temperature co-fired ceramics (LTCC) technology. The proposed VP AiP element achieves a wide bandwidth of $\mathrm{2 4. 2 5 - 2 7. 5} \mathrm{~ G H z}$ and an FBR level exceeding 14 dB within a compact size of 5.8×3.75×2.156 mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup>. Moreover, the proposed PAA achieves a 3-dB scanning range of ± 74° within the operating band. This design offers significant potential for the widespread adoption of AiP modules in mobile terminal applications.