China
Africa
Explore chapters and articles related to this topic
Microwaves in Nonoxidative Conversion of Natural Gas to Value-Added Products
Published in Jianli Hu, Dushyant Shekhawat, Direct Natural Gas Conversion to Value-Added Chemicals, 2020
Xinwei Bai, Brandon Robinson, Dushyant Shekhawat, Victor Abdelsayed, Jianli Hu
Transmission-reflection line method is popular nowadays for complex permittivity and permeability measurement. A vector network analyzer is usually used to determine complex scattering parameters, known as S-parameters. S-parameters indicate the performance of material under different RF/microwave frequencies in terms of incident and reflected waves. It is noticed that the S-parameters changes with frequency. By obtaining S-parameters, computer calculates dielectric constant by using appropriate model (Nicolson–Ross–Weir method, NIST iterative method, etc.). Figure 2.2 shows simplified block diagram of S-parameters determination in a vector network analyzer. Kuek (2012) listed few advantages and disadvantages of transmission/reflection line method: Advantages: Coaxial lines and waveguides are commonly used to measure samples with medium to high loss;Can determine both permittivity and permeability.Disadvantages: Measurement accuracy is limited by the air-gap effects;It is limited to low accuracy when the sample length is the multiple of one-half wavelength in the material.
Microwave Measurement
Published in John G. Webster, Halit Eren, Measurement, Instrumentation, and Sensors Handbook, 2017
Alfons Dehé, K. Beilenhoff, K. Fricke, H. Klingbeil, V. Krozer, H.L. Hartnagel
Scattering parameters describe multiple-port structures in terms of wave variables. The introduction of scattering parameters (S-parameters) arises naturally in microwave circuits and systems, due to the lack of a unique definition for currents and voltages at these frequencies. Most circuits and systems at high frequencies are efficiently described in terms of S-parameters.
TSV fault contactless testing method based on group delay
Published in International Journal of Electronics, 2021
Yuling Shang, Yamin Zhao, Chunquan Li, Min Tan, Lizhen Zeng
The effect of the changing void fault characteristic parameters on the signal integrity of SG-TSV with the contactless probe is analysed, according to S-parameter and group delay (Azizzadeh & Mohammadi, 2008). S-parameter, also called scattering parameter, describes the electrical behaviour of linear electrical network under high-frequency signal excitation for the analysis of the frequency-domain characteristics of the transmission channel. The research object TSV can be simplified as atwo-port network, S21 represents the forward voltage transmission coefficient in the impedance matching. Group delay is the amplitude envelope delay of each signal frequency component when the signal passes through the system. The characteristic parameters of the partially truncated void fault are mainly the radius and the location of the sphere. The spherical voids with radii of 1, 5, and 9 μm are placed in the middle position, respectively. Figure 7 (a) and (b) shows that the S21 of the four cases are coincident, which indicates that the change of the spherical radius has little effect on the efficiency of TSV transmission. The reason is that the void partially truncates TSV, and the uninterrupted part still performs the signal transmission function. The group delay of the TSV with the void is greater than that of the faultless TSV. The reason is that the void causes discontinuous TSV impedance, and the group delay increases with the increasing void radius. If the central Cu conductor and the void are regarded as two regions with different impedance, the larger the cross-section between the two areas as the void radius increases, and the larger the impedance mutation, resulting in the larger the reflection coefficient and the higher group delay. The characteristic parameters of completely truncated void fault mainly include the entirely disconnected height and the void location. Figure 7 (c) shows that the S21 is significantly downward as the disconnection height increases, which indicates aserious attenuation of the signal transmission efficiency, and it is an open-circuit state, and the signal transmission mainly depends on the parasitic capacitance formed between the upper and lower sections of TSV. Moreover, the group delay also decreases significantly.