scholarly journals Generation of ultra-short pulses using the Wilkinson adder

2022 ◽  
Vol 24 (4) ◽  
pp. 46-52
Author(s):  
Anatoly M. Bobreshov ◽  
Aleksey E. Elfimov ◽  
Vladislav A. Stepkin ◽  
Grigoriy K. Uskov
Keyword(s):  
Frequency Band ◽  
Output Signal ◽  
Pulse Shape ◽  
Ultrashort Pulses ◽  
Geometrical Parameters ◽  
Bipolar Pulse ◽  
High Input ◽  
Short Pulses ◽  
S Parameters ◽  
5 Ghz

In this work the possibility of increasing the amplitude of ultra-short pulses and formation of a monocycle Gaussian by adding signals from several oscillators was investigated. For this purpose, the ring adders of Wilkinson design were used. The design of which has been chosen due to low losses and high input decoupling. The S-parameters of the adders with different geometrical parameters have been simulated in the frequency band up to 5 GHz. The obtained results coincided with the experimentally measured characteristics. The monopulse amplitude was increased and a bipolar pulse shape was formed by adding ultrashort pulses of equal and different polarities using the adders. This approach allows you to adjust the parameters of the output signal by adjusting the delays of the triggering signals.

scholarly journals Performance Evaluation of Two Port and Four Port Measurement for Twisted Pair Cable

2018 ◽  
Vol 8 (4) ◽  
pp. 2624
Author(s):  
Azhari Bin Asrokin ◽  
Mohamad Kamal Bin A. Rahim
Keyword(s):  
Performance Evaluation ◽  
Frequency Band ◽  
Measurement Technique ◽  
Network Analyzer ◽  
Differential Mode ◽  
Twisted Pair ◽  
The Core ◽  
S Parameter ◽  
Measurement Results ◽  
S Parameters

A balance-unbalance (balun) transformer is commonly used to connect the balance 100 Ohm twisted pair cable to the unbalance 50 Ohm network analyzer ports, but due to the limitations of the core (i.e. ferrite) inside the balun, the balun can only effectively operates at a certain band of frequencies. This limitation can be eliminated by using a 4-port vector network analyzer (VNA) which is done by connecting the VNA’s ports to each conductor end. The extracted S-parameters will then be transformed to a 2-port S-parameters in differential mode at both ports. To validate the measurement technique, S-parameter measurement by using the 4-Port Network Analyzer without any balun will be compared to the measurement which used the 2-Port Network Analyzer with the balun transformers. Two twisted pair cable distances are selected as reference which are 500, and 1000 meters with nominal copper diameter of 0.5mm. Based on the measurement results, the 4-ports measurement shows good correlation with the 2-ports measurement especially at 500m distance. This shows that the 4-ports measurement setup is suitable to be used to measure twisted pair copper cable and possible to measure at a higher frequency band such as up to 500 MHz but at a shorter twisted pair cable distance.

Research of a Dynamic Vibration Absorber with Tunable Resonant Frequency and its Vibration Attenuation Characteristics

2014 ◽  
Vol 511-512 ◽  
pp. 601-605
Author(s):  
Qiang Ma ◽  
Jie Jian Di ◽  
Xiao Wu Du ◽  
Quan Liang Zhao
Keyword(s):  
Resonant Frequency ◽  
Frequency Band ◽  
Vibration Absorber ◽  
Geometrical Parameters ◽  
Dynamic Vibration Absorber ◽  
Damping Effect ◽  
Dynamic Vibration ◽  
Vibration Attenuation ◽  
Working Frequency ◽  
Attenuation Characteristics

In order to improve working frequency band and damping effect of a dynamic vibration absorber, a new kind of dynamic vibration absorber is presented. Its resonant frequency could be real-time adjusted by adapting the stiffness of the spring. The vibration attenuation characteristics are analyzed theoretically and numerically. According to simulation analysis, effects of geometrical parameters are researched and optimum geometric parameters are determined. The damping effect was simulated in a flat structure, the results show that the working frequency band and damping effect of the DVA are both remarkable.

scholarly journals Why Use Ultrashort Pulses in Ophthalmology and Which Factors Affect Cut Quality

Medicina ◽  
2021 ◽  
Vol 57 (7) ◽  
pp. 700
Author(s):  
Bojan Pajic ◽  
Brigitte Pajic-Eggspuehler ◽  
Christian Rathjen ◽  
Mirko Resan ◽  
Zeljka Cvejic
Keyword(s):  
Femtosecond Laser ◽  
Cataract Surgery ◽  
Femtosecond Lasers ◽  
Pulse Length ◽  
Ultrashort Pulses ◽  
Nonlinear Effects ◽  
Ophthalmic Surgery ◽  
Short Pulses ◽  
Cut Quality ◽  
Cutting Effect

The power density of femtosecond lasers and exposure time to the tissue are crucial for a successful procedure in terms of safety and precision. The reduction of the pulse duration allows reducing the quantity of the energy to be delivered to the tissue for disruption with strongly diminished mechanical and thermal collateral damage. The cutting effect of ultra-short pulses is very precise, minimally traumatic, safe, and predictable. Future developments will lead to further energy reductions to achieve optical breakdowns. However, the pulse length cannot be shortened arbitrarily because below 100 fs nonlinear effects can change the process in an unfavorable way. Compared to manual-conventional cataract surgery, femtosecond laser-assisted cataract surgery (FLACS) shows many advantages in clinical application, especially with regard to precision and tissue protection. The femtosecond laser has become particularly important and has made the overall procedure safer when we deal with complex cataract cases such as subluxated lenses. We provide an overview of the evolution of femtosecond laser technology for use in refractive and cataract surgeries. This article describes the advantages of available laser platforms with ultrashort pulses and mainly focuses on the technical and physical backgrounds of ophthalmic surgery technologies.

scholarly journals Design and Implementation of Super Wide Band Triple Band-Notched MIMO Antennas

2021 ◽  
Author(s):  
Bazil Taha Ahmed ◽  
Darío Castro Carreras ◽  
Eduardo Garcia Marin
Keyword(s):  
Frequency Band ◽  
Wide Band ◽  
Mimo Antenna ◽  
Mimo Antennas ◽  
A Value ◽  
Radiating Element ◽  
S Parameters ◽  
Different Shapes ◽  
Working Frequency ◽  
Triple Band

AbstractIn this article, a triple band-notched super-wideband (SWB) monopole antenna is designed and manufactured. The measured working frequency band (out of the filters working band) ranges from 2.5 to 20 GHz. A single radiating element is utilized to analyze and implement various MIMO antennas, with isolation between the antenna ports higher than 15 dB. Two parallel-fed elements SWB MIMO antenna and four parallel-fed elements SWB MIMO antennas are presented. Metallic barriers with different shapes are used to improve the isolation among ports from a low unacceptable value of 12 dB to a value higher than 20 dB within most of the working frequency band. S-parameters of the presented SWB MIMO antennas experimentally shows that antennas perform well up to 20 GHz, which is the highest frequency supported by the available Vector Network Analyzer used in the S parameters measurements. Satisfactory performance is observed up to 50 GHz by computer simulations using the CST software.

Strong amplitude modulation of the radiation emitted by buried mesa-structure heterolasers in a frequency band up to 5 GHz

1990 ◽  
Vol 20 (2) ◽  
pp. 171-174 ◽  
Author(s):  
I S Goldobin ◽  
V D Kurnosov ◽  
Andrei G Plyavenek ◽  
A F Solodkov ◽  
N V Shelkov ◽  
...  
Keyword(s):  
Frequency Band ◽  
Amplitude Modulation ◽  
Mesa Structure ◽  
Strong Amplitude ◽  
5 Ghz

scholarly journals Metamaterial based on an inverse double V loaded complementary square split ring resonator for radar and Wi-Fi applications

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Md. Rashedul Islam ◽  
Mohammad Tariqul Islam ◽  
Mohamed S. Soliman ◽  
Mohd Hafiz Baharuddin ◽  
Kamarulzaman Mat ◽  
...  
Keyword(s):  
Frequency Band ◽  
Ring Resonator ◽  
Weather Radar ◽  
Split Ring Resonator ◽  
Unit Cell ◽  
Double Negative ◽  
Split Ring ◽  
X Band ◽  
Resonance Frequencies ◽  
5 Ghz

AbstractIn this research paper, an inverse double V loaded complementary square split ring resonator based double negative (DNG) metamaterial has been developed and examined numerically and experimentally. The electromagnetic (EM) properties of the proposed inverse double V-structure were calculated using computer simulation technology (CST-2019) and the finite integration technique (FIT). The designed metamaterial provides three resonance frequencies are 2.86, 5, and 8.30 GHz, covering S-, C-, and X-bands. The total size of the recommended unit cell is 8 $$\times$$ × 8 $$\times$$ × 1.524 mm3, and a high effective medium ratio (EMR) value of 13.11 was found from it. The − 10 dB bandwidths of this structure are 2.80 to 2.91, 4.76 to 5.17, and 8.05 to 8.42 GHz. The proposed structure's novelty is its small size, simple resonator structure, which provides double negative characteristics, high EMR, maximum coverage band, and required resonance frequencies. Wi-Fi network speeds are generally faster when frequencies in the 5 GHz band are used. Since the proposed structure provides a 5 GHz frequency band, hence the suggested metamaterial can be used in Wi-Fi for high bandwidth and high-speed applications. The marine radars operate in X-band, and weather radar works in S-band. Since the designed cell provides two more resonance frequencies, i.e., 2.86 GHz (S-band) and 8.30 GHz (X-band), the proposed metamaterial could be used in weather radar and marine radar. The design process and various parametric studies have been analyzed in this article. The equivalent circuit is authenticated using the advanced design system (ADS) software compared with CST simulated result. The surface current, E-field, and H-field distributions have also been analyzed. Different types of array structure, i.e., 1 $$\times$$ × 2, 2 $$\times$$ × 2, 3 $$\times$$ × 3, 4 $$\times$$ × 4, and 20 $$\times$$ × 25 is examined and validated by the measured result. The simulated and measured outcome is an excellent agreement for the inverse double V loaded CSSRR unit cell and array. We showed the overall performance of the suggested structure is better than the other structures mentioned in the paper. Since the recommended metamaterial unit cell size is small, provides desired resonance frequency, gives a large frequency band and high EMR value; hence the suggested metamaterial can be highly applicable for Radar and Wi-Fi.

scholarly journals Analytical Solutions for the Propagation of UltraShort and UltraSharp Pulses in Dispersive Media

2019 ◽  
Author(s):  
Er'el Granot
Keyword(s):  
Dispersive Medium ◽  
Ultrashort Pulses ◽  
Analytical Approximation ◽  
Dispersive Media ◽  
Physical Realization ◽  
Technical Literature ◽  
Short Pulses ◽  
New Findings ◽  
Analysis Of Dispersion ◽  
Analytical Expressions

Ultrashort pulses are severely distorted even by low dispersive media. While the mathematical analysis of dispersion is well known, the technical literature focuses on pulses, which keep their shape: Gaussian and Airy pulses. However, the cases where the shape of the pulse is unaffected by dispersion is the exception rather than the norm. It is the object of this chapter to present a variety of pulses profiles, which have analytical expressions but can simulate real-physical pulses with greater accuracy. In particular, the dynamics of smooth rectangular pulses, physical Nyquist-Sinc pulses, and slowly rising but sharply decaying ones (and vice-versa) are presented. Besides the usage of this chapter as a handbook of analytical expressions for pulses' propagations in a dispersive medium, there are several new findings. The main ones are: Analytical expressions for the propagation of chirped rectangular pulses, which converge to extremely short pulses; analytical approximation for the propagation of Super-Gaussian pulses; the propagation of Nyquist Sinc Pulse with smooth spectral boundaries and an analytical expression for a physical realization of an attenuation compensating Airy pulse.

scholarly journals Optimization Design and Simulation of Light Broadband Multilayer Composite Absorber

2021 ◽  
Author(s):  
Ping-an Yang ◽  
Yuxuan Huang ◽  
Rui Li ◽  
Yang Sun ◽  
Xin Huang ◽  
...  
Keyword(s):  
Frequency Band ◽  
Multilayer Structure ◽  
Optimization Design ◽  
Design Method ◽  
Magnetic Loss ◽  
Absorption Capacity ◽  
Multilayer Composite ◽  
Absorption Bandwidth ◽  
Specific Frequency ◽  
5 Ghz

Abstract Multilayer plate structure is an effective way to design the absorbing coating with excellent performance. Based on the analysis of the electromagnetic (EM) absorbing principle of multilayer structure, this paper selects materials with magnetic loss type and resistance loss type to establish the database of EM parameters. Genetic algorithm is used to optimize the design of the multilayer structure. Finally, COMSOL is used for simulation verification. The results show that the multilayer materials prepared by different types of EM loss materials have the characteristics of large absorption bandwidth and strong absorption capacity. When optimizing for different frequency bands and the thickness is limited to 5 mm, the absorption band can be adjusted freely between 5 GHz and 15 GHz by selecting the materials and thickness of each layer, which solves the limitation that a single material only meet the requirements in a specific frequency band. When optimizing for absorption intensity, the minimum reflection loss (RLmin) can reach -30.7 dB and the effective absorption bandwidth (EAB) is 3.3 GHz (13.1 GHz -16.4 GHz) achieved with only 2.44 mm. This design method provides the possibility to design multilayer composite materials with high absorption and low reflection in a wider frequency band range.

Sign in / Sign up

Export Citation Format

Share Document