A dual-band low-profile patch antenna, which operates based on aperture-coupling mechanism, is exploited to measure the permittivity of a sample under test (SUT) in the microwave frequencies and send the measured data simultaneously. The upper resonant frequency, which is considerably affected by changing the permittivity of the SUT, can be utilized for sensing purpose. In contrast, the lower resonant frequency is almost independent of the samples hence can be used as the communication link. The samples are placed on top of the feeding side of the structure. The variation in the sample’s permittivity leads to changes in the input impedance of the sensor antenna. While this change results in having different feedline-dependent resonant frequencies, the cavity-dependent resonant frequency is almost preserved intact for different samples. The sensor antenna is designed using electromagnetic solver and an equivalent circuit is proposed to model its behavior. The effect of varying parameters in the equivalent model is investigated. Moreover, by fabricating the sensor, the measurement results show that by changing the permittivity of samples from 1 to 12.85, the upper band resonant frequency (feedline-dependent) shifts from 12.30 to 11.37 GHz (78 MHz per unit dielectric constant). Nevertheless, the small variation in resonant frequency and radiation characteristics of the antenna in the lower band (cavity-dependent) can provide a stable communication channel with respect to the SUT. This link with a reasonable 2.8% (9.54-9.81 GHz) 10-dB impedance bandwidth can be reserved for sending the measured and pilot data in a wireless sensor system.

中文翻译：

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使用带有用于数据传输的分配链路的传感器天线进行高分辨率介电常数测量

一种基于孔径耦合机制的双频段低剖面贴片天线用于测量被测样品 (SUT) 在微波频率下的介电常数并同时发送测量数据。受 SUT 介电常数变化影响很大的谐振频率上限可用于传感目的。相比之下，较低的谐振频率几乎与样本无关，因此可以用作通信链路。样品放置在结构进料侧的顶部。样品介电常数的变化导致传感器天线输入阻抗的变化。虽然这种变化导致具有不同的馈线相关谐振频率，但对于不同的样本，与腔相关的谐振频率几乎保持不变。传感器天线是使用电磁求解器设计的，并提出了一个等效电路来模拟其行为。研究了等效模型中不同参数的影响。此外，通过制造传感器，测量结果表明，通过将样品的介电常数从 1 更改为 12.85，上频带谐振频率（取决于馈线）从 12.30 GHz 移至 11.37 GHz（每单位介电常数为 78 MHz）。尽管如此，低频段（与腔相关）天线的谐振频率和辐射特性的微小变化可以为 SUT 提供稳定的通信信道。该链路具有合理的 2.8% (9.54-9.81 GHz) 10-dB 阻抗带宽，可保留用于在无线传感器系统中发送测量和导频数据。