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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Optimization of a Multi-Receiver FMCW Radar for Snow Cover Monitoring
摘要： Microwave radars represent an interesting solution to monitor the internal structure of the snow cover because the measurements are practically instantaneous, non-destructive, and can be remotely controlled to improve the safety of the operators. In particular, an innovative radar architecture based on two receivers can deliver, at the same time, the depth and the dielectric permittivity of the snow cover, this latter directly related to the physical parameters of the snow, such as the density. These parameters are fundamental to provide an accurate forecast for the avalanche formation. This paper presents the optimization of the dual-receiver radar architecture, in terms of the reciprocal distance between the transmitter and the receivers. Preliminary experimental results are also presented.
关键词： dielectric permittivity,stratigraphy,multi-receiver architecture,FMCW radar,monitoring,snow avalanche
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - A Scatterometer Operating at Millimetre and SubMillimetre Wave Wavelengths
摘要： A scatterometer operating in the bands from 50 to 750 GHz has been designed and fabricated. Operation in the different bands is achieved by using a Network Analyser with appropriate frequency extenders and corrugated horns. The beam is propagated using reflective quasi-optics on two levels with the sample being mounted on the lower level. The two levels are connected by a rotating periscope which collects the scattered radiation from the sample and transfers it to the upper level where the phase and amplitude are measured by the Network Analyser. The scatterometer can measure in both reflection and transmission and in VV, HH, VH and HV polarisations. During a measurement the Network Analyser heads and associated cables remain static to prevent drift. Rough reference samples have been developed for testing the scatterometer and preliminary results are reported in the 50 - 75 GHz band.
关键词： scattering,permeability,permittivity,materials,propagation,antenna,measurement
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Dielectric Properties Measurement Based on Split Ring Resonator For Microfluidic Characterization
摘要： In this work, a bridge element approach based on the circular SRR configuration is proposed for accurate measurement in terms of complex permittivity and the loss tangent. It is observed that the proposed inter-connected bridge structure based on split ring resonator provides better sensitivity for dielectric measurement when compared with the standard microwave SRR sensors. The sensor operating at 1 to 6 GHz frequency range with 2.5μL sample volume at a time. The mathematical derivation is generated by loading sample with a standard reference of the materials in order to develop the empirical model for the determination of complex permittivity and the loss tangent. As demonstrated by the results, the unloaded Q-factor improves more than 400 over the narrow bandwidth at operating frequency of 2.3 GHz and provides less than 5 dB of the insertion loss. The measured data of each sample are in good agreement with the corresponding reference values available in the literature having a typical average detection error of less than 2.04%. By comparison, this design has an identical performance goal and provides excellent sensing capability which can be implemented in chemical and biosensor applications.
关键词： resonator,sensor,split ring resonator,permittivity
更新于2025-09-04 15:30:14
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The effect of titanium excess and deficiency on the microstructure and dielectric properties of lanthanum doped Ba0.55Sr0.45TiO3 with colossal permittivity
摘要： The temperature dependent dielectric properties of (Ba0.54875Sr0.44875La0.0025)Ti(1+x)O3 with both an excess and a deficiency of 0.25 mol.% TiO2 were investigated. The samples were prepared by the mixed oxide method and sintered in a conventional oven at temperatures ranging from 1400 °C to 1475 °C. The cubic perovskite structure was confirmed with XRD at room temperature. The sample with an excess of 0.25 mol.% Ti exhibited reduced grain growth while abnormal grain growth was observed for samples without Ti modification. Samples exhibited colossal permittivity for all modified compositions. With a 0.25 mol.% deficiency of Ti a permittivity over 65,000 and a tan δ under 0.05 were measured over a temperature range of -68 °C to 150 °C and a frequency range between 50 kHz and 1 MHz. This paper shows that by fine tuning the composition, materials with new, exciting and widely adjustable dielectric properties can be achieved.
关键词： Doping,Colossal permittivity,Lanthanum,BST
更新于2025-09-04 15:30:14
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Copper Cobalt Magnetic Ceramic Materials Characterization at Terahertz Frequencies
摘要： This study presents the complex index of refraction and the complex permittivity of a magnetic ceramic material made of copper, cobalt, and iron oxides. The index of refraction and the extinction coefficient of the CuCo-ferrite exhibit an almost frequency independent behavior and were averaged to n = 3.62 ± 0.05 and k = 0.06 ± 0.02, respectively, over the frequency range from 0.2 to 1 THz. The corresponding complex permittivity was ε’ = 13.12 ± 0.35 for the real part and ε’’ = 0.46 ± 0.15 for the imaginary one. The absorption coefficient and the transmittance of the CuCo-ferrite were also determined. The absorption coefficient exhibits a dip at ~0.35 THz, which corresponds to a peak in transmittance at this frequency. The impact of the observations on the potential realization of novel THz electronic devices is discussed.
关键词： Terahertz,Ferrites,Transmission,Permittivity,Refractivity
更新于2025-09-04 15:30:14