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Ambient Backscatter Communication
Published in Parag Chatterjee, Robin Singh Bhadoria, Yadunath Pathak, 5G and Beyond, 2022
Tushar S. Muratkar, Ankit Bhurane, Ashwin Kothari, Robin Singh Bhadoria
Xu et al. [52] proposed trend-based modulation and a code-assisted demodulation technique, using which they built a battery-free ViTag that achieves an uplink data rate of up to 1 kbps. The authors analyzed performance of their VLBCS in terms of success probability and network capacity using stochastic geometry [53]. Specifically, the network topology is modeled using a generalized Gauss-Poisson process. They also studied the impact of the duty cycle and reflection coefficient on system performance, and observed that a larger value of the duty cycle causes more interference and hence decreases the success probability. Also, the reflection coefficient should have an appropriate value. This is because too small and too large values of the reflection coefficient result in reduced received power at the receiver and larger interference power, respectively. Authors in [54] built an ambient light BackCom system that is capable of backscattering the data at a rate of 100 bps for 10 cm distance.
Manipulation of Light
Published in Araz Yacoubian, Optics Essentials, 2018
When light propagates between two dielectric interfaces (such as air to glass interface), part of it is reflected. (Light consists of electric and magnetic fields, hence the name electro-magnetic radiation.) The reflection coefficient is the ratio of the amplitude of the reflected and incident electric field. Similarly, the transmission coefficient is the ratio of the amplitude of the reflected and incident electric field. The reflection and transmission coefficients (for normal incidence) are given by () r=n1−n2n1+n2 () t=2n1n1+n2
Monolithic Microwave IC Technology
Published in Mike Golio, RF and Microwave Semiconductor Device Handbook, 2017
Reflection coefficient (G): Another way of expressing the impedance. The reflection coefficient is defined as how much signal energy would be reflected at a given frequency. Like impedance, the reflection coefficient will vary with frequency if inductors or capacitors are in the circuit. The reflection coefficient is always defined with respect to a reference or characteristic impedance (=(Z – Z0)/(Z + Z0)). For example, the characteristic impedance of one typical TV transmission line is 75 ohms, whereas another type of TV transmission line has a characteristic impedance of 300 ohms. Hooking up a 75 ohm transmission line to a 300 ohm transmission line will result in a reflection coefficient of value (300 – 75)/(300 + 75) = 0.6, which means 60% of the energy received from the antenna.
Effects of memory response and impedance barrier on reflection of plane waves in a nonlocal micropolar porous thermo-diffusive medium
Published in Mechanics of Advanced Materials and Structures, 2023
Anand Kumar Yadav, Erasmo Carrera, Eckart Schnack, Marin Marin
Reflection coefficient is the energy share of a reflected wave in the energy of the incident wave at the reflecting boundary. The variation of the reflection amplitude ratio of reflected and waves against incident angle of wave for alternative values of nonlocal parameter (solid curve with solid hollow square) (solid curve with single tick) and (solid curve with double tick) when, for is shown in Figure 4(a)–(f). A wave’s energy contribution to the wave’s incident energy at the reflecting boundary y = 0 is known as the reflection coefficient.
Long range guided waves for detecting holes in pipelines
Published in Journal of Structural Integrity and Maintenance, 2020
Salisu El-Hussein, John J Harrigan, Andrew Starkey
A drilled circular hole was then created at the mid-length of the 100 m model pipe. The displacement-time and the spectrograph for Point 1 are plotted in Figures 10(a) and 10(b). The incident signal, end reflection and the reflection from the hole are indicated by I, RE and RH respectively. From this Figures 10(a) and 10(b), it is difficult to note any reflection. However, when the reflected signal was zoomed and plotted, the reflection from the hole is visible as shown in Figure 11(b). The intensity of the spectrum was observed to be increasing with increasing hole diameter. Table 2 gives the summary of reflection coefficients for different excitation frequencies and hole diameters. The reflection coefficient was calculated as the ratio of the amplitude of the incident signal to the reflected signal. Cross correlation signal processing was then used to detect and locate the position of the hole. The cross correlation of I (Figure 12(a)) and RH (Figure 12(b)) produces a higher peak time shifted signal (Figure 12(c)), indicating similarity between them. The figure shows a shift of the peaks in the two impulses, shown at 0.05 in Figure 12(c). This indicates a positive time shift of 0.01s since the cross correlation for signals occurring at the same time would show peaks at 0.04 (the length of the original impulse windows).
PSO AND IFS TECHNIQUES FOR THE DESIGN OF WEARABLE HYBRID FRACTAL ANTENNA
Published in International Journal of Electronics, 2021
Sandeep Singh Sran, Jagtar Singh Sivia
he Reflection Coefficient or scattering parameter is the most significant parameter of the antenna. The reflection coefficient is defined as the ratio of voltage or Electromagnetic waves radiating in desired direction to the voltage or Electromagnetic waves radiating in the opposite direction to the antenna. The decibel (dB) scale is used to calculate the scattering parameters. The required reflection coefficient value should be small than −10 dB. The reflection coefficient of MKWHFA is analysed from 1 GHz to 10 GHz frequency range. The comparison between the first and second iteration’s scattering parameters of the proposed antenna is shown in Figure 6.