Analysis of chaotic behaviour in lumped-distributed circuits applied to practical microwave oscillators

A general method for the analysis of pre-chaotic and chaotic behaviours in lumped-distributed circuits has been developed. Examples of practical microwave oscillators, namely Gunn and IMPATT oscillators were designed. The simulation and measurement results showed that these oscillators possess regions of periodic, quasi-periodic, and chaotic spectra. The method could be used by circuit designers to design chaos free oscillators.<

A Family of Modular Fully Differential Switched-Capacitor Filters for Stimulating Ladder Filters

The switched capacitor filters proposed in this paper are based on the simulation of LC ladder filters through the state variable equations. They include all-pole and finite transmission zero, lowpass filters, bandpass and highpass filters. The introduced family of filters has a fully differential structure; consequently it has the advantages of improved power supply and common mode rejection ratios and extended dynamic range. Since the proposed family of filters simulates LC ladder filters, it inherits their low passband sensitivities. One of the main advantages of this family of filters is that it has a modular structure composed of key and auxiliary circuits. This modular structure results in easier design and implementation procedures in VLSI fabrication. The double-sampling concept is applied to the introduced modular blocks, which is essentially needed in high-frequency applications. A comparison with similar published work available in the literature is presented and illustrative examples are given

Chaos in microwave systems

The presentation reviews microwave circuits that exhibit chaotic behaviour and will emphasise the need for microwave designers to examine the possibility of circuits becoming chaotic. The paper gives the basic analysis tools for examining the stability of microwave circuits and several examples reported in the literature will be presented

Non-linear system and subsystem modelling in the time domain

This work describes how non-linear subsystems can be modelled from time domain measurements. The advantage being the simplicity of the measurement and the developed models and the speed of the simulation of the entire system

Time domain modelling of microwave systems and subsystems

A new method of modelling non-linear microwave system and subsystem is presented. Non-linear models of the subsystem are identified and then combined to solve the entire system. Throughout the procedure time domain modelling and simulation is used but frequency domain characteristics can also be obtained. Models of non-linear subsystems are identified from time domain measurement which require less measurement time compared to frequency domain measurement. Black box models are used instead of equivalent circuits. The identified models are time domain transfer functions and this offers flexibility and saving in the amount of data stored for each model

Nonlinear system and subsystem modeling in time domain

Nonlinear models of microwave subsystems are identified from time domain measurements, Scattering functions in the form of nonlinear time domain functions are used to derive a system identification model instead of an equivalent circuit. The advantage being the simplicity of the measurement and the developed models and the speed and accuracy of the simulation of the entire system

Calculating the impedance of patch antennas using TLM

The 3-D transmission line matrix (TLM) method is used to calculate the input impedance of patch antennas. The feed line to the antenna is simulated using a TEM line consisting of two electric and two magnetic walls. This simulation has the advantages of matching to the input microstrip and of having a known reference impedance. These two advantages makes accurate calculation of the input impedance possible. The results were compared to previously published measured dat

Interfacing the transmission line method (TLM) and state-space (SS) techniques to analyse general non-linear structures

The paper describes a technique for analysing general electromagnetic structures including distributed regions and lumped non-linear sub-circuits, employing the transmission-line-matrix and the state space method. The analysis is entirely performed in the time domain. The technique took advantage of each of the methods and offers a wide range of applications especially for the analysis of general electromagnetic structures at high frequencies

Synthesis, molecular docking study, and biological evaluation and of new thiadiazole and thiazole derivatives incorporating isoindoline-1,3-dione moiety as anticancer and antimicrobial agents

To highlight the importance of thiazole and thiadiazole derivatives in the progression of cancer and microbial treatments and to aid in drug design, we have synthesized a new series of 1,3,4-thiadiazole and 1,3-thiazole derivatives. These were created by a two-step reaction process: initially, 2-(4-(2-bromoacetyl)phenyl)isoindoline-1,3-dione was reacted with potassium thiocyanate, and then the resulting thiocyanate intermediate was coupled with aryl diazonium salts to produce iminothiadiazole derivatives. These derivatives served as crucial intermediates for further synthesizing a range of thiadiazole derivatives using different reagents. Additionally, treating 2-(4-(2-bromoacetyl) phenyl)isoindoline-1,3-dione with thiourea resulted in aminothiazole derivatives. These were further coupled with arenediazonium chloride to form 5-arylazoaminothiazole derivatives. All the synthesised compounds were characterised using IR, 1H NMR and 13C NMR spectrum data, as well as physical data. The assessment of the synthesized compounds on the HCT-116 human colon cancer cell line has yielded promising results. Specifically, compounds 3a, 3b, 4b, 5b, 6b, and 9b have shown noteworthy efficacy, suggesting their potential as anticancer agents. These compounds have demonstrated a greater potency compared to the standard drug, doxorubicin, highlighting their significance in cancer treatment research. The study assessed the activity of various newly synthesized compounds against diverse microorganisms, including bacteria and fungi. Notably, two of these compounds, specifically 4b and 7b, exhibited significant efficacy against both gram-positive and gram-negative bacteria, surpassing the performance of a standard antibacterial reference agent. Furthermore, molecular docking of new products revealed interactions with enzyme binding sites, aligning with in vitro findings. Additionally, in-silico studies confirmed their favourable oral bioavailability through ADME profiling