Circularly polarized slot antennas based on dual-mode elliptic substrate integrated waveguide (SIW) cavities are proposed in this letter. Current distribution on the dual-mode cavity is analyzed first to facilitate the layout design. The antennas are divided into three categories. For the first one, three unbalanced slots are etched on the upper surface of the cavity with a central rectangular slot placed perpendicularly to the arc-shaped slots on the two sides of the long axis. For the other two antennas, two pairs of symmetric arc-shaped slots are etched on the upper surface of the cavity. One of them has an additional shorting-pin in the center. Circular polarization is achieved by simultaneously exciting two quasi-TM110 cavity modes and combining them in the 5–6 GHz frequency range. The working principle of the dual-mode antennas is theoretically illustrated in detail and experimentally verified. The proposed antennas offer attractive features, including novel working principle, simple structure, low loss, low profile, low cost, and good gain, appearing as good candidates for indoor communication.

中文翻译：

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双模椭圆腔圆极化缝隙天线

在这封信中提出了基于双模椭圆衬底集成波导 (SIW) 腔的圆极化缝隙天线。首先分析双模腔上的电流分布，以方便版图设计。天线分为三类。第一种是在型腔上表面蚀刻三个不平衡槽，中间矩形槽垂直于长轴两侧的弧形槽。另外两个天线在腔体的上表面蚀刻有两对对称的弧形缝隙。其中一个在中心有一个额外的短路销。圆极化是通过同时激发两个准 TM110 腔模并将它们在 5-6 GHz 频率范围内组合来实现的。从理论上详细阐述了双模天线的工作原理并进行了实验验证。所提出的天线具有吸引人的特点，包括新颖的工作原理、简单的结构、低损耗、低剖面、低成本和良好的增益，是室内通信的理想选择。