This article presents a comprehensive study on shorted dipole antennas aiming for low-cost radio frequency identification (RFID) reader applications. Starting from a low-profile shorted bowtie dipole antenna, it is found that by varying the shorting wall position, three different types of resonant antennas could be realized with different radiation features. A low-profile planar inverted F antenna (PIFA) -type dipole is obtained by moving the shorting wall toward the feeding, which exhibits a low resonance frequency without obvious back lobe radiation or sidelobes. When the shorting wall is placed in the middle of the radiating patch, a mushroom-type dipole antenna can be built. A zeroth-order mode is also observed. This structure differs from the magnetoelectric dipole due to a low-profile structure. Placing the wall toward the end of the dipole arm leads to a loop-type antenna with a broader beam and a reduced gain. It also shifts the resonance toward the higher frequency. Based on the PIFA- and mushroom-type structures, two circularly polarized antennas with crossed shorted dipoles are designed and investigated carefully. Finally, two optimized, compact, and low-cost RFID reader antennas based on simple metal stamping process and screws are designed, fabricated, and tested, showing an excellent RF reading range. This study demonstrates that for the shorted dipole antennas, miniaturization and bandwidth control can be achieved simultaneously. Particularly, for higher gain and smaller size, the shorting wall should be placed close to the feeding to suppress the loop mode. For omnidirectional radiation, the loop mode should be enhanced by moving the shorting wall close to the end of the dipole arm.

中文翻译：

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用于低成本 RFID 阅读器应用的短路偶极天线的表征

本文介绍了针对低成本射频识别 (RFID) 阅读器应用的短路偶极天线的综合研究。从低剖面短路蝴蝶结偶极天线开始，发现通过改变短路墙位置，可以实现具有不同辐射特性的三种不同类型的谐振天线。通过将短路壁移向馈电获得低剖面平面倒F天线（PIFA）型偶极子，其表现出低谐振频率，没有明显的后瓣辐射或旁瓣。当短路墙放置在辐射贴片的中间时，可以构建蘑菇型偶极天线。还观察到零阶模式。由于低剖面结构，该结构不同于磁电偶极子。将墙放置在偶极臂末端会导致环形天线具有更宽的波束和降低的增益。它还将共振移向更高的频率。基于PIFA型和蘑菇型结构，设计并仔细研究了两个具有交叉短路偶极子的圆极化天线。最后，基于简单的金属冲压工艺和螺钉设计、制造和测试了两个优化的、紧凑的、低成本的 RFID 读取器天线，显示了出色的 RF 读取范围。该研究表明，对于短路偶极子天线，可以同时实现小型化和带宽控制。特别是对于更高的增益和更小的尺寸，短路墙应靠近馈电放置以抑制环路模式。对于全向辐射，