This article proposes a reconfigurable low-profile monopolar antenna with triple-band independent tuning capability. The antenna is based on the concept of a center-fed patch with shortings to achieve omnidirectional radiation patterns. Instead of using vias, varactor-loaded stubs are utilized to create reconfigurable equivalent shorting points. The triple bands can be achieved by using three sets of stubs. This configuration results in three magnetic current loops that spatially overlap at different independently tunable frequencies. Measurement results show that the design obtains three independent tunable frequencies centered at 2.51, 3.56, and 4.62 GHz with -10 dB relative tuning ranges of 22.8%, 22.8%, and 16.7%, respectively. The antenna radiates omnidirectionally with vertical polarization in the three sweeping bands. The proposed concept can be extended to a larger number of bands by adding sets of stubs with considerations of coupling and impedance matching.

中文翻译：

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具有独立可调性的三频可重构低剖面单极天线

本文提出了一种具有三频独立调谐功能的可重构低剖面单极天线。天线基于中心馈电贴片的概念，带有短路以实现全向辐射图。代替使用过孔，而是将变容二极管负载的短截线用于创建可重新配置的等效短路点。可以通过使用三组存根来实现三重频带。这种配置导致三个磁电流回路在不同的独立可调频率上在空间上重叠。测量结果表明，该设计获得了三个独立的可调频率，分别位于2.51、3.56和4.62 GHz，其-10 dB相对调谐范围分别为22.8％，22.8％和16.7％。天线在三个扫描带中以垂直极化全向辐射。