«上一篇
 文章快速检索 高级检索

 应用科技  2019, Vol. 46 Issue (3): 21-24  DOI: 10.11991/yykj.201810008 0

### 引用本文

LONG Zhuo, LIU Changjun. A dual-band substrate integrated waveguide permittivity measurement system[J]. Applied Science and Technology, 2019, 46(3), 21-24. DOI: 10.11991/yykj.201810008.

### 文章历史

A dual-band substrate integrated waveguide permittivity measurement system
LONG Zhuo , LIU Changjun
School of Electronics and Information Engineering, Sichuan University, Chengdu 610064, China
Abstract: In order to measure complex permittivity under different frequencies, a permittivity measurement system is designed to measure complex permittivities at S- and C-band, which is based on a substrate integrated waveguide structure. In the vicinity of 2.45 GHz and 5.85 GHz, the complex permittivities of the object can be measured simultaneously. The sensor of the test system includes two square resonant cavities cascaded diagonally, two test slots and a microstrip feed coupling structure. The working bands of the two slits are independent of each other, and the two slits on the surface of the object to be measured contacting the sensor affect the resonant frequency and quality factor of the system. The complex permittivity of the object to be measured was obtained based on the inversion of the artificial neural network. The simulation data were used to train the artificial neural network. In the verification stage, the accuracy of the sensor was checked by using mixed solutions of ethanol and water with different concentrations. Compared with the theoretical value, at 2.45 GHz, the maximum relative errors of the real and imaginary parts of complex permittivities were 1.98% and 1.28%; and at 5.85 GHz they were 2.51% and 2.68% respectively. The sensor has high precision and dual-frequency measurement characteristics.
Keywords: substrate integrated waveguide    dual-band sensor    artificial neural network (ANN)    complex permittivity    microwave measurement    resonant frequency    quality factor    resonant cavities

1 传感器原理与测量方法 1.1 基片集成波导谐振原理及分析

 $f_{{\rm{mnp}}}^{{\rm{SIW}}} = \frac{1}{{2{\rm{\text π}}\sqrt {\varepsilon \mu } }}\sqrt {{{\left( {\frac{{m{\rm{\text π}}}}{{{L_{{\rm{eff}}}}}}} \right)}^2} + {{\left( {\frac{{n{\rm{\text π}}}}{h}} \right)}^2} + {{\left( {\frac{{p{\rm{\text π}}}}{{{W_{{\rm{eff}}}}}}} \right)}^2}}$ (1)

 ${W_{{\rm{eff}}}} = {W_{{\rm{SIW}}}} - 1.08\frac{{{D^2}}}{{{S_{{\rm{VP}}}}}} + 0.1\frac{{{D^2}}}{{{W_{{\text{SIW}}}}}}$
 ${L_{{\rm{eff}}}} = {L_{{\rm{SIW}}}} - 1.08\frac{{{D^2}}}{{{S_{{\rm{VP}}}}}} + 0.1\frac{{{D^2}}}{{{L_{{\rm{SIW}}}}}}$

 $\frac{1}{{{Q_u}}} = \frac{1}{{{Q_c}}} + \frac{1}{{{Q_d}}}$ (2)

 ${Q_d} = \frac{{\varepsilon '}}{{\varepsilon ''}} = \frac{1}{{\tan\; \delta }}$ (3)

1.2 传感器仿真及测试

2条缝隙位于传感器的对角线上每个腔体中心位置，长度分别接近于工作频率下的四分之一波导波长。随着待测物介电常数的变化，传感器的谐振频点和品质因数都会随之变化。图3是传感器的实物以及介电常数测量系统，传感器表面的矩形方框是附加测试槽，它使得液体类待测物能够始终保持在腔体的电场最强处，并保证每次测量的用量一致，根据理论分析和实验验证表明附加测试槽对腔体的谐振结构不产生影响。

2 神经网络反演系统及反演结果 2.1 神经网络反演系统

2.2 复介电常数反演过程和结果

3 结论

1）提出一种可用于S和C波段的介电常数测量系统，经过加工测试，仿真与实测数据吻合良好；

2）在介电常数反演过程中，成功利用人工神经网络技术加速推演过程；

3）利用乙醇与水混合二元溶液进行测量系统精度验证，介电常数实部和虚部的相对误差在2.45 GHz分别为1.98%和1.28%，5.85 GHz分别为2.51%和2.68%。

 [1] WAGNER N, EMMERICH K, BONITZ F, et al. Experimental investigations on the frequency and temperature-dependent dielectric material properties of soil[J]. IEEE transactions on geoscience and remote sensing, 2011, 49(7): 2518-2530. DOI:10.1109/TGRS.2011.2108303 (0) [2] 位宇, 陈潇杰, 刘臻龙, 等. 两路15kW连续波微波磁控管相干功率合成技术[J]. 应用科技, 2018, 45(2): 34-37. (0) [3] 吴秉琪, 刘长军. 一种测量微波介质基板复介电常数的方法[J]. 应用科技, 2018, 45(4): 100-103. (0) [4] WALDRON I, MAKAROV S N, BIEDERMAN S, et al. Suspended ring resonator for dielectric constant measurement of foams[J]. IEEE microwave and wireless components letters, 2006, 16(9): 496-498. DOI:10.1109/LMWC.2006.880708 (0) [5] VERMA A K, NASIMUDDIN, OMAR A S. Microstrip resonator sensors for determination of complex permittivity of materials in sheet, liquid and paste forms[J]. IEEE proceedings-microwaves, antennas and propagation, 2005, 152(1): 47-54. DOI:10.1049/ip-map:20041155 (0) [6] LIU Changjun, TONG Fan. An SIW resonator sensor for liquid permittivity measurements at C band[J]. IEEE microwave and wireless components letters, 2015, 25(11): 751-753. DOI:10.1109/LMWC.2015.2479851 (0) [7] LIU Changjun, PU Yang. A microstrip resonator with slotted ground plane for complex permittivity measurements of liquids[J]. IEEE microwave and wireless components letters, 2008, 18(4): 257-259. DOI:10.1109/LMWC.2008.918894 (0) [8] SHIGEKI F. Waveguide line: 06-053711[P]. Japan, 1994-02-25. (0) [9] 胡南. 论分层基片集成波导功分器及宽带功率放大器研制[J]. 科学技术创新, 2018(3): 25-26. DOI:10.3969/j.issn.1673-1328.2018.03.014 (0) [10] 林彬彬, 周春霞, 王玉洁, 等. 基于半模基片集成波导的滤波功分器设计[J]. 微波学报, 2017, 33(S1): 140-143. (0) [11] POZAR D M. 微波工程[M]. 张肇仪, 周乐柱, 吴德明, 等译. 北京: 电子工业出版社, 2006: 238-242, 256-261. (0) [12] XU Feng, WU Ke. Guided-wave and leakage characteristics of substrate integrated waveguide[J]. IEEE transactions on microwave theory and techniques, 2005, 53(1): 66-73. DOI:10.1109/TMTT.2004.839303 (0) [13] MKADEM F, BOUMAIZA S. Physically inspired neural network model for RF power amplifier behavioral modeling and digital predistortion[J]. IEEE transactions on microwave theory and techniques, 2011, 59(4): 913-923. DOI:10.1109/TMTT.2010.2098041 (0) [14] SATO T, CHIBA A, NOZAKI R. Dynamical aspects of mixing schemes in ethanol–water mixtures in terms of the excess partial molar activation free energy, enthalpy, and entropy of the dielectric relaxation process[J]. The journal of chemical physics, 1999, 110(5): 2508-2521. DOI:10.1063/1.477956 (0)