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Periodic moment method (PMM) is a useful tool to solve electromagnetic (EM) scattering problems for periodic structures. Double integrals over the cross section of the reference element are performed in the spectral domain formulation. Cross section of reference element of two-dimensional periodic structures; such as wedge absorber, is divided into different shape of cells to obtain scattering behavior...
In this study, a frequency selective surface consisting of open ring resonator arrays on glass substrate is proposed for filtering TM-polarized 2.6 GHz frequency band by using equivalent inductance and capacitance expressions and full-wave electromagnetic simulation. The FSS is evaluated for different permittivity, strip and gap width as well as strip length and periodicity values and the transmission...
Ground penetrating radar (GPR) is an electromagnetic sensor based on the ultra-wideband radar technology that can also be used for through-the-wall (TTW) target recognition. Search for the presence of designated targets hidden behind the walls, such as stationary or moving human bodies or certain types of weapons, is addressed in various critical applications; in rescue missions after earthquakes...
Military systems are exposed to electromagnetic fields that are originated internally or externally during the whole operational life cycle. Military systems should perform their critical operational missions without any functional/performance degradation. In the case of military systems, due to the complexity of the complete vehicle electronic system architectures, electromagnetic compatibility requirements...
Technological improvements and dense use of wireless systems has led to an increase in exposed electromagnetic radiation (EMR) levels in recent years. The effects of these EMRs on the population have not been completely characterized despite intense research on this topic. For this reason accurate evaluation of EMR levels in the environment have become essential. Therefore, this study aims to determine...
We present computational analysis of optical chiral metamaterials that consist of helical metallic elements. At optical frequencies, metals are modeled as penetrable objects with plasmonic properties. A rigorous implementation based on boundary element methods and the multilevel fast multipole algorithm is used for efficient and accurate analysis of three-dimensional structures. Numerical results...
A recently introduced potential integral equations for stable analysis of low-frequency problems involving dense discretizations with respect to wavelength are solved by using the fast multipole method (FMM). Two different implementations of FMM based on multipoles and an approximate diagonalization employing scaled plane waves are developed and used for rigorous solutions of low-frequency problems...
We present design and computational analysis of log-periodic antennas that are fabricated by using low-cost inkjet printing technology. The designed antennas operate in the 1.5–2.5 GHz range and are suitable for diverse applications, including energy harvesting at WiFi and GSM bands. Suitable designs are fabricated by using silver-based inks in standard commercial printers. Despite the challenges...
Today, railways have numerous communication, navigation, propulsion, power and control systems. These systems are operating in a very limited space resulting in significant interference issues. Therefore, it is crucial to take into the account the Electromagnetic Compatibility (EMC) through the project life time starting in the design stage. This paper presents briefly the EMC management and control...
This paper presents the optimal controller design for an improved battery charger structure which can be supplied from a photovoltaic power system. The transfer characteristic of the presented converter is the same as a buck/boost converter. Therefore, even in extreme conditions, the presented converter has the ability to extract the maximum power from the photovoltaic power system and charge the...
Evolution of modern communications and radar systems have steadily increased the demand on modelling the propagation effects with real world scenarios for various signal types. The main purpose of this research is to create a flexible, generic and realistic Radio Frequency (RF) environment simulator including both radar and communication signals. Software defined radio (SDR) platform has been utilized...
The main idea of this study is to investigate the small signal gain analysis of the helix type Traveling Wave Tube's (TWT's). Dispersion equation of the TWT is discussed and the behavior of propagation constants of the helix TWT structure is expressed when beam-wave interaction occurs. All possible waves or modes which play important role in the amplification process are considered. The effects of...
Signal penetration into missiles through nose cone and apertures is critical for electro-optical guidance systems, navigation equipment and control of explosive ordnance. Penetrated signals are relatively small but hard to simulate by known computational methods. To corroborate simulation results, we created a scaled version of a missile and placed wire antennas inside this mock missile. The prototype...
A pulse transmitter operating at VHF band has been designed using a pulse generator circuit and a pulse amplifier. The pulse generator circuit has been built using commercially available digital logic integrated circuits by taking advantage of the propagation delay characteristics. The pulse generator circuit produces a very short pulse in the order of several nanoseconds which is amplified by an...
Silicon carbide (SiC) devices are attracting attention as next generation power device because of their high breakdown voltage, low conduction loss, and fast switching speed compared with conventional Silicon (Si) device. SiC power device is expected to be used in electric vehicle and hybrid electric vehicle. The large di/dt and dv/dt in fast switching operation interact with parasitic component in...
The use of electromagnetic shielding materials continues to grow in terms of research and application at various areas. In this paper, shielding effectiveness measurements are conducted to investigate the behavior of three different materials against electromagnetic fields. These materials are copper wire mesh, galvanized wire mesh, and aluminum plate. The purpose of using wire mesh structures is...
Emanations from the information technology equipment may contain classified information being processed by the device. Shielding is one of the important techniques used for TEMPEST precaution and shielded window films can be viewed as the specific intent to prevent classified information processed within a building/area from being intercepted. The purpose of this work is to investigate the effectiveness...
In this study, metamaterial absorber structures that operate in the mid-wave infrared (MWIR) region are presented. The advantage of the design stems from the high absorptance in the region of interest and the ease of fabrication. Fabrication stage is facilitated by large in-plane geometric dimensions of the metamaterial pattern and small thickness of the full absorber geometry.
This paper presents a study of the Characteristic Basis Finite Element Method (CBFEM), which is an advanced numerical method that can be used in EMC applications. The CBFEM is a non-iterative domain decomposition technique employing characteristic basis functions, and it provides considerable reduction in matrix size and convenient parallelization, both of which make use of direct solvers in a memory-...
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