Design and Optimization of Microwave Sensor for the Non-Contact Measurement of Pure Dielectric Materials

Abstract

This article presents an optimized microwave sensor for the non-contact measurement of complex permittivity and material thickness. The layout of the proposed sensor comprises the parallel combination of an interdigital capacitor (IDC) loaded at the center of the symmetrical differential bridge-type inductor fabricated on an RF-35 substrate (εr = 3.5 and tanδ = 0.0018). The bridge-type differential inductor is introduced to obtain a maximum inductance value with high quality (Q) factor and low tunable resonant frequency. The central IDC structure is configured as a spur-line structure to create a high-intensity coupled electric field (e-field) zone, which significantly interacts with the materials under test (MUTs), resulting in an increased sensitivity. The proposed sensor prototype with optimized parameters generates a resonant frequency at 1.38 GHz for measuring the complex permittivity and material thickness. The experimental results indicated that the resonant frequency of the designed sensor revealed high sensitivities of 41 MHz/mm for thickness with a linear response (r2 = 0.91567), and 53 MHz/Δεr for permittivity with a linear response (r2 = 0.98903). The maximum error ratio for measuring MUTs with a high gap of 0.3 mm between the testing sample and resonator is 6.52%. The presented performance of the proposed sensor authenticates its application in the non-contact measurement of samples based on complex permittivity and thickness.

Integrated Passive Device-Based Gas Sensor Combined with PANI/SnO2 Composites for Ammonia Detection

“…A SnO 2 /bionic porous (BP) carbon composites-based thick film material is prepared, and an ultra-narrowband microwave filter based on microwave transmission technology is designed to verify the sensing performance of ammonia at room temperature . In other fields of microwave sensor technology, the low-temperature co-fired ceramic and substrate-integrated waveguide also have been used in research on gas sensing, but in the field of IPD technology, a large number of studies devoted to the development of filters, detections of biological solutions, investigations of environmental humidity, characterizations of dielectric materials, construction of diplexers and dividers, there are few reports about gas sensors based on integrated passive device (IPD) technology. The IPD-based microwave sensor exhibits higher microwave performance by using a lower loss GaAs substrate, more complex design structures and micro–nano processing technology, small size, and easy integration compared to the planar microwave devices.…”

Real‐Time and High‐Accuracy Microwave Frequency Identification Based on Ultra‐Wideband Optical Chirp Chain Transient SBS Effect

“…Real-time and high-accuracy measurement can provide the time-frequency characteristic of microwave signals in a realtime dynamic fashion, while enabling clear analysis of the generating source. In recent years, such measurements have quickly attracted interest for applications in astronomy, [1][2][3] communications, [4] materials, [5][6][7][8] medicine, and healthcare, [9][10][11][12][13][14][15] and devices. [16] For these applications, electronic solutions are the most straightforward and widely implemented microwave measurements today.…”

Assessing Land Cover Transformation for Urban Environmental Sustainability through Satellite Sensing

“…Land use/land cover (LULC) changes influence the structure, functioning and capacities of natural ecosystems [1][2][3][4]. The resultant modifications in land cover produce indelible imprints on the natural and social environments at the local level [2,5].…”

“…The street and park trees, the woodland in the urban and peri-urban fringes of study area 4. Shrubs/Tall herbs Vegetation cover dominated by shrubs/tall herbs.5Bare soil/rocks Barren lands with extremely low vegetative coverage.…”