Okan Mert Yucedag

Radar cross section calculation of a wind turbine modeled by PEC canonical structures

Wind turbines are electrically large and complex objects that act as scatterer for electromagnetic waves. Thus, they may cause performance degradation for radar systems. Radar simulations are useful tools to obtain suitable wind turbine sites around radar bases. Radar cross section (RCS) calculation is an important step in radar simulations. In this work, RCS of a wind turbine which is modeled by canonical structures is calculated analytically and validated with Physical Optics (PO) method.

Performance analysis of compressive ISAR imaging for complex targets

In this paper, performance efficiency analysis of compressive inverse synthetic aperture radar (ISAR) imaging for a complex, electrically large target is presented. In this context, physical optics (PO) is used as a high-frequency scattered field prediction technique and compressive sensing (CS) theory is applied to ISAR imaging by exploiting the sparse point scatterer structure of the target. Results prove that CS provides high resolution and accuracy in ISAR imaging even under the Nyquist sampling rate and linearly decreases computational time.

Wind farms' interference effects on the error performance of wireless line-of-sight communications using binary digital modulations

The main objective of this paper is to examine the deterioration on the average error performance of military and civilian wireless communications systems (WCSs) that are in the vicinity of wind farms. By treating the total interference signal caused by any wind turbine (WT) as the ensemble of scattering signal replicas over the uniformly segmented parts of the WT that face different Doppler frequency shifts, path loss factors, etc., the time-varying characteristics of the total signal have been investigated by means of the varying configuration parameters. To expose the degrading effects of the wind farms on the received signal and the overall error performance of the WCSs, the scattering signal contribution of the segments of the mast and blades have been evaluated analytically by also taking physical optics-based radar cross-section (RCS) estimation method into account. Average bit error rate performances of digital modulation schemes have been examined theoretically and numerically via Monte Carlo simulations through the entire rotation period of the blades. With the aim of providing useful insights on the assessment of the performance degradation caused by the WT interference, this paper exposes miscellaneous numerical results related to different configurations and settlings.

Investigation of wind farm effects on radar multiple target tracking

The increasing demand on wind farm (WF) installations has been raising the necessity and significance of performance assessment of electronic systems in the vicinity of WFs. Using a signal model for WF scattering, the interaction between the wind turbines (WTs) and pulse-Doppler radars (PDRs), the effects of WTs on the PDRs’ detection and tracking processes are investigated in this study. The extensive examination in this study provides insightful perspectives on the tracking performance of PDRs that are employing global nearest neighbor or probabilistic data association methods for the multiple target tracking operation under WF scatterings by exhibiting statistical metrics related to the track losses, false tracks depending on several system parameters, and WF configurations. Additionally, a novel WF design approach that is focused on minimizing WF effects on radar tracking performance is proposed in this study. The signal and tracking model employed in the examination provides a baseline for the analysis for WF-radar interactions, and the proposed WF design approach is promising to minimize the deteriorating effects of WFs on radar tracking performance.

Investigation of deteriorating effects of wind farms on SAR imaging

In this work, a Synthetic Aperture Radar (SAR) signal model that considers the rotational movement and scattering of wind turbines is proposed. The Radar Cross Sections (RCS) of the wind turbines that are modelled via the assembly of canonical structures are included in the signal model and the deteriorating effects of wind farms on SAR images are investigated. These SAR images are compared to the SAR images that are obtained without using RCS values and the significance of considering the time-varying scattering characteristics of wind turbines on SAR imaging is put forth.

Investigation of dipole antenna radiation pattern over planar lossy half-space

Monopole and dipole antennas have been commonly used especially in wireless communications. Therefore, the electrical properties of these types of antennas on their location affect the antenna radiation pattern which is important for efficiency of the communication system. In this study, for different electrical properties with ground planes -very dry, dry, wet and ice- on which a half wave dipole antennas radiation pattern how changed was analysed by utilizing from the method of moments solution of Hallens integral equation and image theory with reflection coefficient approximation.

Cross section optimization of offset parabolic reflector antenna for cosecant-squared radiation pattern

This paper presents cross section optimization of offset parabolic reflector antenna structure to obtain cosecant-squared pattern for microwave surveillance radars. Analytical Regularization Method (ARM) and Artificial Neural Network (ANN) are used as a pre-design and optimization tool.

Parametric analysis of open-ended waveguide array feeder for cosecant-squared and pencil beam radiation pattern

This paper deals with the parametric analysis of an open-ended waveguide array, which is used as feeder for parabolic reflector antennas. The main aim of the study is to obtain desired radiation characteristics for air and coastal surveillance radars such as, pencil beam, suppressed side lobes, electronic beam scanning and cosecant-squared pattern shapes. The analytical regularization method is used a fast and accurate way to solve the problem of E-polarized wave diffraction by perfectly electrical conductive (PEC) waveguide array combined with a modified reflector for basic stage of antenna design process. The numerical procedure is initially verified by the analytical methods and the calculated results are presented for the proposed designs.

Parametric analysis of open-ended waveguide array feeder for pattern shaping of parabolic reflector antenna

This paper deals with the parametric analysis of open-ended waveguide arrays, which are used as feeder for the parabolic reflector antennas. The main aim of the study is to obtain desired radiation characteristics for air and coastal surveillance radars such as, pencil beam, suppressed side lobes, electronic beam scanning and cosecant-squared pattern shapes. The analytical regularization method is used a fast and accurate way to solve the problem of E-polarized wave diffraction by perfectly electrical conductive (PEC) cylindrical waveguide array combined with parabolic reflector. The numerical procedure is initially verified by the analytical methods and the calculated results are presented for the proposed designs.