| The development of advanced microwave materials tailored for 5G/6G applications stands as a critical priority on the national agenda.In this context,the characterization of these materials hinges on the determination of complex permittivity and complex permeability,two pivotal parameters governing their electromagnetic properties.The precise assessment of these properties assumes paramount significance,as it exerts a profound influence on the reliability and stability of microwave devices,rendering it an indispensable precondition for the development of cutting-edge microwave components.Across a diverse spectrum of sectors,spanning electronic information,industrial manufacturing,military technologies,aerospace,and beyond,a common challenge persists:the enigmatic or ill-defined electromagnetic characteristics of microwave materials.Consequently,the accurate measurement of these electromagnetic parameters emerges as a pivotal linchpin in the trajectory of pioneering microwave electronic devices.It is imperative to underscore that the precision of these measurements crucially depends on the development of high-performance sensors.Presently,there exist notable lacunae in the realm of microwave electromagnetic parameter measurement sensors.These challenges encompass inadequate performance across a range of frequencies,limited adaptability to varying sample types,and a pressing need for heightened sensitivity.In response to the burgeoning demand for evaluating the electromagnetic attributes of novel materials and addressing the prevailing deficiencies in microwave electromagnetic parameter sensors,this study assumes its focal point: the innovation and refinement of planar microwave sensors tailored to the specific demands of electromagnetic parameter measurement in the 5G frequency spectrum.Based on the Complementary Split Ring Resonator(CSRR)structure,this thesis proposes a range of high-performance,miniaturized planar microwave resonance sensors operating within the 5G frequency range.Furthermore,this thesis explores methods for enhancing sensor sensitivity,expanding the sensor’s measurement range,developing sensors adaptable to sample characteristics,and sensors capable of characterizing magnetic parameters.These contributions address key challenges in material electromagnetic parameter characterization.The main content and primary contributions of this thesis are as follows:Building upon the principles of electromagnetic parameter measurement using planar resonators,this study refines the equivalent circuit of CSRR(Complementary Split Ring Resonator)and analyzes the influence of structural parameters on the resonant frequency.This work lays the foundation for further improvements in the design of planar resonance sensors.Planar microwave sensors are often limited to single-frequency operation due to their inherent characteristics.To extend the measurement range of these sensors,a dual-frequency non-destructive dielectric constant sensor based on the CSRR structure is proposed.The resonant units for both frequency bands utilize complementary split-ring structures.Research findings reveal that resonance frequency and quality factor depend on variations in dielectric constant and loss tangent,demonstrating a clear pattern.This suggests the feasibility of using dual-resonance structures for dielectric parameter measurements.Additionally,to determine the optimal sample thickness,a parametric study is conducted,resulting in inversion expressions for both frequency bands.Measurement results,when compared to reference data from the literature,exhibit an accuracy of 1.5%.Furthermore,the impact of air gaps on measurement accuracy is investigated,highlighting their significance as error sources,with the potential for improved measurement precision through gap elimination.Ceramic materials,commonly found in various shapes and sizes,such as centimeterscale cylinders and cubes,pose challenges when it comes to dielectric constant measurements.Typically,different measurement sensors are required for such samples,adding complexity to the measurement process.To address this challenge,further analysis of the CSRR-based dual-frequency dielectric sensor is conducted,leading to the development of a method for characterizing samples of varying shapes and sizes.By establishing fitting models for each sample,characteristic parameters can be extracted,enabling the same sensor to measure samples of different shapes or sizes.Measurement accuracy,when compared to reference values from the literature,is achieved at 3.5%.This work demonstrates the adaptability of the proposed sensor and measurement method for accurate dielectric measurements on synthetic ceramics of different shapes and sizes,without altering the sensor or sample structures.Further research reveals that differences between measurements in two frequency bands are less than 5%.High dielectric constant liquid materials find crucial applications in the 5G frequency range,but accurately determining their complex permittivity is challenged by low quality factors and insufficient sensitivity.This thesis introduces a high dielectric constant liquid sample measurement sensor based on a multi-element complementary split-ring resonator and proposes a method to enhance measurement sensitivity.The resonator consists of three circular rings designed to effectively improve measurement sensitivity.A central throughhole in the rings accommodates a hollow glass tube for holding the liquid sample,with a volume ratio of 0.36 between the liquid sample and the glass tube.The isolation effect of the quartz glass tube mitigates the impact of high dielectric materials on the resonance sensor,enhancing measurement precision.Compared to rectangular split-ring designs,the proposed ring structure exhibits a larger frequency shift and a 9.1% increase in resonance depth.Experimental validation using ethanol solutions of varying concentrations yields measurement accuracy within 2.8%,affirming the effectiveness of this method.Magnetic dielectric materials find important applications in high-performance antennas and microwave device designs,where both dielectric constant and magnetic permeability are significant factors.However,fully characterizing these parameters faces challenges due to electromagnetic coupling.Addressing this issue,this thesis proposes an electromagnetic isolation sensor based on planar resonator structures and validates its performance.Multiple short-circuit pins are used to separate the electromagnetic field regions,effectively reducing coupling between dielectric constant and magnetic permeability measurements.These short-circuit pins effectively form a Magnetic Cavity Pins(MCP)structure.The resonator structure is used for dielectric constant measurements,while the MCP structure is employed to enhance sensitivity for magnetic permeability measurements.Additionally,to further improve quality factor,a metal patch and two 50Ωchip resistors are integrated on the microstrip line.Two sensors are designed and fabricated for experimental validation,measuring various samples with different dielectric constants and magnetic permeabilities.Results indicate errors in the real and imaginary parts of less than 3% and 6.4%,respectively.The primary innovations of the thesis include:(1)Introducing and implementing a design methodology for dual-frequency planar sensors.(2)Proposing a measurement method with excellent sample adaptability,addressing challenges associated with variations in sample shape and size.(3)Presenting a resonant measurement approach for high dielectric constant liquid samples,mitigating the issue of low quality factor in high dielectric constant measurements.(4)Introducing an electromagnetic isolation sensor,facilitating comprehensive measurements of electromagnetic parameters in magnetic dielectric materials. |
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