In this letter, a low-profile and wideband planar inverted-F antenna (PIFA) based on multiresonant modes is proposed for wireless local area networks and the Internet of Vehicles applications. Through cutting a rectangular slot at the zero-current position of the TM$_{\text{3}/\text{2}, 0}$ mode, a resonant slot mode (TM$_{\text{RS}}$) is excited. Meanwhile, to enhance the impedance bandwidth (IBW), the frequency of TM$_{\text{RS}}$ ($f_{\text{RS}}$) is decreased to close to the frequency of TM$_{\text{3}/\text{2}, 0}$ ($f_{\text{3}/\text{2}, 0}$) by enlarging the length of the rectangular slot. To further enhance the IBW, the frequency of TM$_{\text{1}/\text{2}, \text{2}}$ ($f_{1/\text{2},\text{2}}$) is increased with little change on that of TM$_{\text{3}/\text{2}, 0}$ and TM$_{\text{RS}}$ modes by reducing the length of the rectangular patch. Moreover, capacitive coupled feed is used by loading a small rectangular strip (SRS) on the top of the feeding probe connected with the bottom of the substrate and the ground plane, and the impedance can be matched through adjusting the size of the SRS. To verify the predicted results, the proposed low-profile wideband PIFA is fabricated and measured. The measured results show that the IBW of the proposed PIFA is enhanced to about 33.33% (from 5 to 7 GHz) at the profile of 0.036$\lambda _{0}$ by combining three resonant modes, and it is 7.41 times of 4.5% of the traditional PIFA.

中文翻译：

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基于多谐振模式辐射的薄型宽带 PIFA

在这封信中，提出了一种基于多谐振模式的低剖面宽带平面倒 F 天线 (PIFA)，用于无线局域网和车联网应用。通过在TM的零电流位置切割一个矩形槽$_{\text{3}/\text{2}, 0}$ 模式，谐振槽模式（TM$_{\text{RS}}$) 很兴奋。同时，为了提高阻抗带宽（IBW），TM 的频率$_{\text{RS}}$ ($f_{\text{RS}}$) 降低到接近 TM 的频率$_{\text{3}/\text{2}, 0}$ ($f_{\text{3}/\text{2}, 0}$) 通过扩大矩形槽的长度。为了进一步提高 IBW，TM 的频率$_{\text{1}/\text{2}, \text{2}}$ ($f_{1/\text{2},\text{2}}$) 增加而 TM 变化不大$_{\text{3}/\text{2}, 0}$ 和TM$_{\text{RS}}$通过减少矩形块的长度来调整模式。此外，电容耦合馈电是通过在与基板底部和地平面相连的馈电探针的顶部加载一个小矩形带（SRS），通过调整SRS的大小来匹配阻抗。为了验证预测结果，制造和测量了所提出的低剖面宽带 PIFA。测量结果表明，所提出的 PIFA 的 IBW 在 0.036 的剖面上增强到约 33.33%（从 5 到 7 GHz）$\lambda _{0}$ 通过组合三种谐振模式，是传统PIFA的4.5%的7.41倍。