This letter proposes a low-profile substrate integrated waveguide (SIW) cavity backed self-quadruplexing antenna for wearable transceivers. The full-mode circular SIW cavity is split into four unequal quarter-mode SIW (QMSIW) cavities using the two slots on the upper layer of the cavity. The proposed antenna uses C-shaped and arc-shaped slots of different dimensions in each QMSIW resonator to operate at wireless local area network bands (3.5, 4.9, 5.4, and 5.8 GHz). The measured gains are 4.4, 5.07, 5.40, and 5.7 dBi at 3.5, 4.9, 5.4, and 5.8 GHz, respectively. The antenna is simulated and optimized inside a 48 $\times \text{76}\times$ 21 mm3 rectangular device by keeping the device on the chest of a realistic human model. The proposed antenna has unidirectional radiation patterns in all four operating bands with low backward radiations. Thus, it has low specific absorption rate at all four operating bands.

中文翻译：

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用于可穿戴收发器的紧凑型基于 SIW 的自四工天线

这封信提出了一种用于可穿戴收发器的低剖面衬底集成波导 (SIW) 腔支撑自四工天线。全模圆形 SIW 腔被分成四个不相等的四分之一模 SIW (QMSIW) 腔，使用腔上层的两个槽。建议的天线在每个 QMSIW 谐振器中使用不同尺寸的 C 形和弧形缝隙，以在无线局域网频段（3.5、4.9、5.4 和 5.8 GHz）下运行。在 3.5、4.9、5.4 和 5.8 GHz 下，测得的增益分别为 4.4、5.07、5.40 和 5.7 dBi。天线在 48 $\times \text{76}\times$ 21 mm3 矩形设备内通过将设备保持在真实人体模型的胸部进行模拟和优化。所提议的天线在所有四个工作频段中都具有单向辐射模式，具有低反向辐射。因此，