Design and optimization of hybrid microstrip-SIW bandpass filter on X-band

Bu makalede, X-Bant ’ta hibrit Mikroşerit-YTED (Yalıtkan Taban Entegreli Dalga Kılavuzu) bant geçiren filtrenin optimizasyon çalışması yapılmıştır. Yüksek geçiren bir YTED filtre ile alçak geçiren bir mikroşerit filtrenin seri entegrasyonuyla elde edilen hibrit bant geçiren filtrenin geometrisindeki asimetrik bölümler düzeltilmiştir. Optimizasyon çalışmasında, CST (Computer Simulation Technology) Studio Suite simülasyon programındaki 5 farklı optimizasyon algoritma tekniği hibrit M-YTED bant geçiren filtreye uygulanmıştır. Filtreye uygulanan bu tekniklerin sonuçları karşılaştırılmalı olarak verilmiştir. Metotlar karşılaştırıldığında, geçiş bandındaki S11 değerleri toplamının en düşük değerde olması nedeniyle Parçacık Sürü Optimizasyon Algoritması seçilmiştir. Filtrenin w4 parametresinin değeri 6,165 mm olarak elde edilmiştir. Filtrenin kalite faktörü, optimizasyon çalışmasıyla Guvenli ve diğ., (2021)’nin çalışmasına göre 3,21 kat artırılmıştır. Hibrit Mikroşerit-YTED bant geçiren filtrenin geçiş bandı [ω1-ω2] 7,60 GHz ile 8,40 GHz frekans aralığında, filtrenin merkez frekansı (ω0) 7,90 GHz, filtrenin bant genişliği de 0,80 GHz (%10,01) olacak şekilde tasarlanmıştır. M-YTED bant geçiren filtrenin simülasyon sonuçlarına göre, merkez frekansı 8,15 GHz ve bant genişliği 0,92 GHz'dir (%11,29). Analitik ve simülasyon sonuçları karşılaştırıldığında, analitik sonuçlara göre simülasyon merkez frekansındaki frekans değişimi %1,98 ve bant genişliği değişimi %15’dir. Analitik ve simülasyon sonuçlarının birbiriyle uyumlu olduğu görülmektedir.In this article, the optimization study of hybrid Microstrip-SIW (Substrate Integrated Waveguide) band-pass filter in X-Band has been carried out. Asymmetrical sections in the geometry of the hybrid band-pass filter obtained by serial integration of a high-pass SIW filter and a low-pass microstrip filter are corrected. In the optimization study, 5 different optimization algorithm techniques in the CST (Computer Simulation Technology) Studio Suite simulation program were applied to the hybrid M-SIW bandpass filter. The results of these techniques applied to the filter are given comparatively. Particle Swarm Optimization Algorithm was chosen because the sum of the S11 values in the passband was the lowest when the methods were compared. The value of the w4 parameter of the filter was obtained as 6.165 mm. The quality factor of the filter was increased by 3.21 times with the optimization study according to the study of Guvenli et al. (2021). The passband [ω1-ω2] of the hybrid Microstrip-SIW bandpass filter is designed in the frequency range of 7.60 GHz to 8.40 GHz, the center frequency of the filter (ω0) is 7.90 GHz and the bandwidth of the filter is 0.80 GHz (10.01%). According to the simulation results of M-SIW bandpass filter, the center frequency is 8.15 GHz and the bandwidth is 0.92 GHz (11.29%). When analytical and simulation results are compared, it is seen that frequency change in the simulation center frequency is 1.98% and change in bandwidth is 15%. It is seen that analytical and simulation results are compatible with each other

Tek ve çoklu hedeflerin sınıflandırılması için rezonans bölgede müsic algoritmasına dayalı yeni bir elektromanyetik hedef tanıma yöntemi.

This thesis presents a novel aspect and polarization invariant electromagnetic target recognition technique in resonance region based on use of MUSIC algorithm for the extraction of natural-resonance related target features. In the suggested method, the feature patterns called “MUSIC Spectrum Matrices (MSMs)” are constructed for each candidate target at each reference aspect angle using targets’ scattered data at different late-time intervals. These individual MSMs correspond to maps of targets’ natural-resonance related power distributions. All these patterns are first used to obtain optimal late-time interval for classifier design and a “Fused MUSIC Spectrum Matrix (FMSM)” is generated over this interval for each target by superposing MSMs. The resulting FMSMs include more complete information for target resonances and are almost insensitive to aspect and polarization. In case of multiple target recognition, the relative locations of a multi-target group and separation distance between targets are also important factors. Therefore, MSM features are computed for each multi-target group at each “reference aspect/topology” combination to determine the optimum late-time interval. The FMSM feature of a given multi-target group is obtained by the superposition of all these aspect and topology dependent MSMs. In both single and multiple target recognition cases, the resulting FMSM power patterns are main target features of the designed classifier to be used during real-time decisions. At decision phase, the unknown test target is classified either as one of the candidate targets or as an alien target by comparing correlation coefficients computed between MSM of test signal and FMSM of each candidate target.Ph.D. - Doctoral Progra

Electromagnetic Interference Shielding Effectiveness Performances of Screen Printing Ink and Expanded Graphite Based Composite at X and Ku Bands

In this study, electromagnetic shielding effectiveness and microwave properties (permittivity and permeability) of the expanded graphite (eGR) embedded in screen printing ink (SPI) were investigated. The experimentally measured scattering parameters were utilized within the Nicolson-Ross-Weir (NRW) algorithm to obtain the intrinsic properties at microwave frequencies. Then these parameters were fed into CST Microwave Studio to check the homogeneity behavior of the proposed sample. Initially, a composite containing 7.9 wt% eGR was chosen and all the measurements in experimental setup (solely in waveguide environment) and CST simulations (waveguide and free-space) were performed for the proposed material. About 10 dB/mm shielding efficiency values were satisfied at X and Ku bands (8-18.4 GHz) and homogenous distribution was observed. Afterwards, a superior composite containing higher eGR concentration was searched with a trade-off the thickness and the concentration/cost. At least 57 dB and at most 77 dB shielding effectiveness values were measured for a 2 mm thickness sample having 16 wt% eGR, which results in more than 25 dB/mm shielding effectiveness at X and Ku bands

Radar target classification method with reduced aspect dependency and improved noise performance using multiple signal classification algorithm

This study introduces a novel aspect and polarisation invariant radar target classification method based on the use of multiple signal classification (MUSIC) algorithm for feature extraction. In the suggested method, for each candidate target at each designated reference aspect, feature matrices called 'MUSIC spectrum matrices (MSMs)' are constructed using the target's scattered data at different late-time intervals. An individual MSM corresponds to a map of a target's natural resonance-related power distribution over the complex frequency plane under the chosen aspect angle/late-time interval conditions. The collection of these feature matrices is used first to determine the best late-time interval for optimal feature extraction. Then, the MSM of a target, which are computed over the optimal time interval at all reference aspects, are superposed to obtain the 'fused MUSIC spectrum matrix (FMSM)'. The FMSM of a target is its main classifier feature in the proposed method as the aspect dependency of an FMSM is highly reduced because of its multi-aspect construction process. The suggested method is demonstrated for both simple and complex target geometries such as conducting spheres, dielectric spheres and small-scale aircraft targets with high accuracy rates even for low SNR values using feature fusion at only a few different reference aspects

Electromagnetic Interference Shielding Performance of Ionic Liquid Modified Carbon Black and Graphite in Polyvinylidene fluoride at Ku-Band

In this study, carbon black and/or graphite incorporated with polyvinylidene difluoride (PVDF) composites giving sufficiently high electromagnetic shielding properties at microwave frequencies are synthesized. Micro-scale carbon black and graphite particles are modified by ionic liquid to improve interference shielding properties of PVDF based composites. The negatively charged carbon black and graphite particles are interacted by positively charged imidazolium ring to form ion pairs being embedded in PVDF. The effects of nanoscale hematite, magnetite, maghemite and silver nanoparticles (AgNps) on carbon black incorporated PVDF, graphite incorporated PVDF, and performances of carbon black-PVDF/graphite-PVDF double-layer composites are investigated for the frequency range of 12-18.4 CHz at Ku-band. Among all the composite samples each having 4 mm thickness, double-layer samples exhibit the strongest EMI shielding effectiveness by giving up to 35 dB at minimum in the given frequency range

Real Time Classification of Targets Using Waveforms in Resonance Scattering Region

The classification of similar shaped objects from scattered electromagnetic waves is a difficult problem, as it heavily depends on the aspect angle. The reduction of the adverse effects of the aspect angle is possible by extracting distinguishable features from the scattered signals. In this paper, we propose a target identification method in resonance scattering region using a novel structural feature set based on scattered signal waveform. The feature set carries out a triangularization process to model the hills and valleys of the scattered signal. Once these subwaveforms are identified, their peaks, widths, increase and decrease rates are calculated for each of them. Together with the inter-distance between the sub-waves, feature vector is constructed. Then, cross validation strategies are used to design a classifier using multi-layer perceptron network. The simulations performed by two different target libraries; dielectric rods with different permittivity and small scale aircraft models show very high accuracy of the proposed system in real time

Size-reduced printed log periodic dipole antenna with single first order semi-circle iteration and feed point patches

10th International Conference on Electrical and Electronics Engineering, ELECO 2017; Bursa; Turkey; 29 November 2017 through 2 December 2017This paper presents the miniaturization and improvement of a printed log periodic dipole antenna (LPDA) by using patches at the feeding point and single first order semicircles. After the design of a conventional printed LPDA on FR4 substrate to cover L-band is performed, patches having 12 mm × 5 mm dimensions are placed to the feed point of the antenna. Although this modification gives same antenna size, it brings considerable increase in the return-loss bandwidth up to 2.25 GHz and higher gain values up to 2 GHz at the expense of decrease in gain at about 2.4 GHz. Afterwards, in order to reduce the total size of the antenna, single semicircles are substituted into the dipole arms, which results in 14% lateral size reduction. Besides, the bandwidth is further improved between 0.9 GHz and 2.4 GHz with better return loss performance, higher gain at 2.4 GHz and lower gain variation

Extraction of target poles from electromagnetic scatter signals by using page distribution for target recognition Hedef tanima amaci ile page daǧilimi kullanarak elektromanyetik saçilim sinyallerinden kutup çikarimi

In this paper, we work on the electromagnetic target recognition problem based on the scattered field measurements. These measurements were obtained both in frequency and time domains by using two 0.8-12 GHz horn antennas in bistatic position and HP8720D vector network analyzer. First, the theory of electromagnetic scattering from a target and singularity expansion method (SEM) are summarized. The importance of complex natural resonance frequencies (CNR) in identification problem is discussed in this part. Afterwards, the results of CNR extraction from the scattered data of three dielectric spheres with different sizes and permitivities are presented by using time-frequency techniques to discriminate these targets from each other. It is also demonstrated that Page distribution produces much better results in this respect as compared to Wigner distribution. © 2005 IEEE