Sharif Digital Repository

New mathematical approaches for noise and oscillation analysis of oscillators are presented. First a new approach for computing the phase noise spectrum of microwave oscillators at every offset frequency from the carrier is introduced. This method uses the harmonic balance formulation to obtain time domain functions used in the existing time domain phase noise analysis methods to compute the phase noise spectrum. In spite of the large signal nature of the phase noise in oscillators, it is analytically proved that for the purpose of phase noise calculations for moderate offset frequencies, the phase noise process can be considered as a small signal stationary process. By this consideration, a... 

Today in the most microwave and millimeterwave systems, one or more filters are used due to interference and noise phenomena. Microwave filters are manufactured in different environments such as waveguide, microstrip and SIW. For military and satellite applications that high power handling and low loss are in preference, the only appropriate environment is the waveguide. Other priority which is more important in satellite application is the low weight and small size of the product; Because of that, the idea of dual-mode waveguide filter was proposed in the early 70 decade. These kind of filters are able to produce two poles in one cavity resonator, which can decrease weight and size of the... 

Nowadays, methods based on deep learning networks are the most effective artificial in­ telligence methods. Although they have achieved success in various fields (such as machine vision and object recognition), practical and experimental cases show the fragility of deep learning networks against perturbations and unwanted changes of the input pattern. All these perturbations must be in a way that the main class of the perturbed input pattern can be rec­ ognized by human, but the network makes a mistake in recognizing its correct class. This thesis seeks a more accurate evaluation by designing adversarial attacks such that the main class of the adversarial pattern is detectable by human...