نشریه پژوهش های نوین در سامانه های دفاع الکترونیکی
سال یکم شماره 1 (زمستان 1401)

Today, in medical science, methods such as physical examination, head CT scan, head MRI, angiography, and taking pictures of the skull using X-rays are used to diagnose brain tumors. Nowadays, according to the technological progress, it is possible to send and record microwave waves at high frequencies. Today, in medical science, methods such as physical examination, head CT scan, head MRI, angiography, and taking pictures of the skull using X-rays are used to diagnose brain tumors. Nowadays, according to the technological progress, it is possible to send and record microwave waves at high frequencies.Therefore, microwave radar imaging as a new method can complement current methods and even replace X-ray imaging. In this treatise, three types of microwave imaging such as passive microwave imaging, combined microwave imaging and active microwave imaging have been introduced and then the radar microwave imaging method was discussed in detail. Finally, the new methods of microwave radar imaging for the diagnosis of brain tumors were described. The results have shown that the DMAS-D4 method has a higher resistance to noise and interferences compared to the DAS and DMAS methods.

The goal of this study is to design and implement a new idea for an air-launched missile control unit using digital video processing. In this study, it endeavored to transmit the captured videos through a camera embedded in the nose of the missile via a video transceiver and after processing, the ground station relays the appropriate command to the missile to steer toward its target. Moreover, it’s desired to detect a target in the sky and both stay in one direction until hit the target when intercepting toward the target and the missile intercepts the target in every direction. Additionally, we intend to investigate the launch of a missile in various weather conditions. To identify the type of aerial targets, the dimensions are studied at different intervals, which makes military and non-military goals detected at different intervals. in this investigation, it’s endeavored to study the launch of a missile in three weather conditions including cold, hot, and mild.

Nowadays, superiority in the field of electronic warfare requires the use of the appropriate techniques and tools at the right time. One of the important inventions in counter-electronic measures is digital radio frequency memory (DRFM), which plays an important role in counter-electronic systems. This tool is a telecommunication signal storage system that increases the effectiveness of the interference system against complex waveforms by several decibels. The analysis of these signals in DRFM is done with the help of signal processing tools. In this research, the optimized proposed interference based on the definition of the objective function will improve the performance of the coordinated beam forming. Based on the proposed coordinated beam former, the result of the performance of the disruptive actions in electronic warfare will be done. In the proposed method, the proposed coordinated beams try to maximize the sum of the perturbation rates by presenting a target function. The proposed method is evaluated on the criteria of bit error rate and generated interference. The evaluation results show a reduction in bit error rate of up to 6% compared to the method and an interference of up to 5% compared to the beam generator in line with the increase in the number of targets.

In this paper, a smart antenna with wide spatial coverage is designed, simulated and fabricated. This antenna is low-cost and easy fabrication with the operating frequency of 2.4 GHz that can be used in wireless systems. This antenna consists of single FR4 substrate, this substrate consists of planar 4×4 Butler Matrix and 1×4 microstrip planar array antenna. This antenna has determined specific four radiation patterns in the directions± 15 degree and± 58 degree that its radiation pattern can be switched to each of these four radiation patterns. The main advantage of designed antenna in compare with other smart antennas are implemented on a single substrare or multilayer substrates, degree of spatial coverage is 154 and also features of this antenna are simple and low cost fabrication, low weight and low lrofile. This antenna has four input and symmetrical structure, with two symmetrical input ports excitioan, antenna's bandwidth is equal to 19.4% and with other two symmetrical input ports excitioan, antenna's bandwidth is equal to 11.0%. Optimization by CST software has been used in all steps of Butler matrix design and microstrip antenna. Smart antenna is fabricated to better evaluate its performance and its feature is measured in laboratory, the results of this measurement are close to that of the simulation ones.

In this paper circular monopoly plasma antenna that is excited by surface wave is designed and simulated by using HFSS. The radiation pattern is compared with the antenna made of aluminum with the same dimensions. Also the dependence of plasma parameters on radiation characteristics of the designed antenna will be investigated.

The Concentric Circular Array Antennas (CCAAs) are made up of elements that are distributed on different concentric circular areas with different radiuses. In this paper we determine the non-uniform distribution of elements excitation amplitude and their positions, in order to achieve more reduction in sidelobe level and beam width. The difference of side lobe levels becomes more important when the beam width of the antenna needs to be kept fixed. The sidelobe level reduction is proposed as an optimization problem and a Genetic Algorithm (GA) is used to handle the large mass of parameters that associate with each other. In this article, experiments have been performed for 3 different cases. In the first case, it is assumed that 18 elements have been distributed on 3 centered rings, and in second case we assumed that 24 elements have been distributed on 7 non-uniform distribution centered rings and in third case 30 elements are distributed on 6 non-uniform distribution centered rings. Based on the results obtained, for first case the proposed method represents -1.89 dB reductions, for second case the proposed method represents -8.16 dB reduction, and For third case also the first sidelobe level -0.44 dB Reduced.The results showed that the design of the non-uniform distribution of elements with non-uniform excitation amplitude for CCAAs, decreased significantly the sidelobe level and beam width.