نشریه مهندسی مخابرات جنوب
پیاپی 24 (تابستان 1396)

Antenna arrays are one of the most susceptible types of antennas in this field due to having the necessary capabilities for beam shaping, beam conduction, direction, and high gain. In general, in pattern synthesis of an array of antennas, the main focus is on determining the excitation of the antennas to produce a desired pattern. The problem of determining the excitation of the antennas in the array can be divided into three main categories. The first issue of antenna pattern synthesis is the production of a pattern whose zeros are in the desired directions. The second problem is the production of a pattern with a very narrow beamwidth that the level of the lateral petals is very low compared to the main petal. The third problem is the production of a shaped beam. In this paper, the pattern synthesis of an array of antennas with very narrow beams and very low lateral petal surface area compared to the main petal is discussed. There are several different ways to do this in antenna articles and books. One of these methods is Newton binomial method. In this paper, a linear array is used to produce a very narrow beam and reduce the surface of the lateral petals using Newton Pattern Synthesis.

Image segmentation is an essential step in image analysis. This article deals with the segmentation of brain images based on the intensity of brain magnetism. Each medical image of a human contains distinct areas. These areas can be represented by the wavelet coefficient. Classification of these properties can be performed using the fuzzy classification method. Edge recognition techniques have been used to identify the edge in the input image. The Silhouette method has been used to determine the power of the categories. Eventually, the different areas of the image become color-coded and encoded.

In multi-path feeding, the delay and Doppler range determine the type (frequency selector, flat) and speed (slow, fast) of the feed, respectively. OFDM has shown good performance with orthogonal subcarriers and shielding time intervals. Although the shield period can delete the ISI, the received symbol still interferes with its self-returns from the multi-path component. Using adaptive beam-forming array algorithms, we can reduce co-channel interference without the need for channel estimation to apply the equalizer (especially in acute interference conditions). In addition, directing the main beam in the desired direction and the zeros in the direction of interference will increase the BTS antenna gain, reduce the power consumption of the phone and increase the network capacity. In this paper, the performance of MMSE algorithms in OFDM systems in different channel conditions is compared.

Analog multiplication of two signals is one of the most important applications in signal processing. The main motivation for choosing an analog current multiplier is its importance in the function of nonlinear analog signal processing. The multiplier is used as a programming element in systems such as filters, neural networks, and as mixers and modulators in a telecommunications system. And are widely used in end-of-life frequency modulation conversion control filters for fuzzy integrated systems and so on. Quadruple multiplication has a non-linear function in signal processing that is very useful for communication equipment and control systems, and CMOS technology is widely recognized as the most desirable technology for implementing integrated circuits. Therefore, comparison and evaluation of current quadruple multipliers in terms of power consumption, total THD harmonic distortion, frequency response, linearity, speed, input voltage range, input current range, noise, power supply, and other parameters affecting quadruple current multiplier circuits are necessary to achieve a multiplier with proper performance and use in specific applications.

Undoubtedly, studying the guidance of tactical nesting missiles without considering proportional navigation is a very difficult task. And researchers have always tried to develop and eliminate the weaknesses of these guidance laws and their various strategies, to prevent disturbances in the missile control system. This article also discusses the various strategies for improving the traditional true proportional navigation law and its equations. And then by drawing graphs and comparing their equations, the superior strategy in different modes is introduced.

Array codes are error-correcting codes of very low complexity, originally used for hacking and decryption in RAID and other storage applications. The structure of these codes is very simple and the implementation of coding and decoding algorithms for them is easy. Although these codes have a high rate, due to their design limitations, they do not get the highest possible rate. In fact, Hamming codes get the highest possible rates for their design structure. In this paper, we compare the rate and complexity of array codes when compared to Hemingway codes and provide a more efficient rate for these codes by using the structure of Heming code in array codes.