Mehmet Ciydem

In this article, we introduce a positioning system developed for two- and three-dimensional motion tracking. The system is based on a recursive Bayesian estimator with a dynamic naive Bayesian classifier map matching scheme. The states of the dynamic naive Bayesian classifier are created by using the map information and partitioning the region of interest into grids. The developed positioning system considers three types of measurements of the platform at each time instant: the heading measurement to determine the prior probability distribution; the single-anchor distance and altitude measurements to determine the observation likelihood. A recursive Bayesian estimator takes advantage of these measurements to obtain the posterior probability distribution. Ultimately, via the obtained posterior probability distribution, the most probable projection of these measurements onto the states of the dynamic naive Bayesian classifier is estimated as the current position of the platform. To avoid the potential ambiguities in the estimation process, the estimator exploits a design parameter that characterizes the platform’s maximum attainable speed. Simulations and real-time application results are given to illustrate the effectiveness of the developed system for positioning applications in two- and three-dimensional indoor and outdoor environments with constraints, such as corridors, roads, or flight paths.

This study introduces a compact, wideband dual-polarized suspended patch antenna designed for LTE700/LTE850/CDMA850/GSM900 applications, with a focus on achieving high isolation. The antenna design has two suspended patches that are excited in orthogonal directions using a modified crossed-slot configuration. The modifications applied to the crossed-slot significantly enhance the −15 dB impedance bandwidth, resulting in improved port isolation between polarizations. Both theoretical analysis and experimental testing confirm these enhancements, revealing an impressive −15 dB impedance bandwidth of 37% (688-1000 MHz) and port isolation exceeding 35 dB in the operating band. The antenna exhibits symmetric and directional radiation patterns in principle planes, with half-power beamwidths ranging from 55.32º to 65.61º and 61.79º to 66.84º. Antenna gain show exhibits variation in the range of 7.3-8.4 dBi across the measured frequencies. The compact size of the antenna, measuring 380 × 380 × 43.6 mm³, makes it highly suitable for integration into commercially deployed base stations. Throughout the paper, we provide a detailed presentation of the antenna's geometry, feeding mechanism, parametric studies, and experimental results. The combined theoretical analysis and practical experimentation validate the success of the proposed antenna design, highlighting its potential for robust performance in a wide range of communication applications.

This paper presents a new waveform correlation based method which determines the individual harmonic voltage contributions of Electric Arc Furnace (EAF) plants supplied from a point of common coupling (PCC). The method is based on the waveform correlation computations between the PCC voltage and the feeder current at the individual harmonic frequency. PCCs supplying multiple EAF plants usually suffer from high voltage harmonic components due to their operation principles. A relationship between the correlation coefficient of the PCC voltage and the feeder current waveforms, and the harmonic voltage contribution of each plant is derived and this relationship is used to derive the individual contributions to the PCC voltage. The main idea of the method is based on the fact that harmonic voltage at the PCC is a result of the additive effect of voltage drops on the source side impedance of the power system caused by the individual feeder currents. No real-time impedance measurements are required in the proposed method and no need for the measurements of the other feeders to compute the contribution of a specific feeder in contrast to some previously proposed methods for the same problem. The proposed method is further expanded in order to reveal the effects of the compensation systems of the EAF plants, which identifies the harmonic current sinking problem of a victim plant with a powerful compensation system using further correlation computations between the feeder currents and in-plant current measurements. The proposed method can be easily adapted as a real time harmonic contribution detection tool for the already-installed power quality analyzers, most of which employ synchronized voltage and feeder current waveform measurements.

In this research work, a new harmonic responsibility measure is proposed to extract the amount of harmonic responsibility of each plant supplied from the point of common coupling (PCC). The proposed method uses a function of the correlation coefficients between the voltage and current signals measured synchronously at the PCC. After the verification of the method on synthetic data generated in simulation environment, field data measurements of voltage and current are used to test the practicability of the proposed method. Harmonic contributions of the iron and steel (I&S) plants obtained using the proposed method are compared with the results of one existing method in the literature and it has been shown that harmonic responsibilities of the plants can be obtained for each harmonic order. The harmonic currents absorbed by the shunt harmonic filters of the I&S plants from the rest of the system are also identified effectively with the proposed method to determine the actual source of the harmonics. The proposed method can serve the needs of the active power filters and other compensation systems to improve the effectiveness of those systems in reducing individual distorting effects of the I&S plants supplied from a PCC of the electricity transmission system.

This paper presents a simple, compact, low cost, low profile, dual polarization, suspended patch antenna design to operate in 3.3-3.8 GHz band for 5G base stations. Proposed antenna comprises a main radiating patch, a secondary parasitic patch, modified L-probe feeds, and a vertical metal wall. Main patch is capacitively driven by two feeds for dual (±45° slant) polarization. Vertical metal wall is used in order to increase the port isolation. Parasitic patch also helps further improvement of input impedance matching (|S11|, |S22|) and port isolation (|S21|). Prototyped antenna has |S11|, |S22| < -10 dB and |S11|, |S22| < -15 dB impedance bandwidth of 45% and 36% respectively. Port isolation is |S21| < -30 dB in desired operating band. Stable and symmetric radiation patterns with half power beam-widths of 56°-65° are obtained in E/H-planes. Numerical calculations and experimental results are reported and discussed.

Bu makalede 1710-2170 Mhz bandında çalışan, geniş bantlı, çift kutuplu askıda yığın plaka anten tasarımı ve geliştirmesi ele alınmıştır. Anten, klasik yama antenlerin beslemesinden farklı olarak, kapasitif kuplaj beslemeli iki adet askıda yığın plaka anten elemanından oluşmaktadır. Kutuplanma çeşitlemesi sağlamak için anten, ±45° doğrusal kutuplu bağımsız çift kanallı tasarlanmıştır. Anten elemanları, kanallar arasında yüksek izolasyonu sağlamak için yatayda ve dikeyde optimal aralıklarla yerleştirilmiştir. Eleman tasarımdan başlayarak, antenin tasarımı, benzetimleri, üretimi ve ölçümleri yapılmıştır. Geri dönüş kayıpları, kanal izolasyonu, ışıma örgüsü, kazanç vb anten performansına ilişkin sonuçlar verilmiş ve benzetimler ile ölçümlerin tutarlı olduğu görülmüştür.

Double-sided split-step MM-wave Fresnel lenses: design, fabrication and focal field measurements

An isolation enhancement technique for a wideband (1.71–2.17 GHz) and ±45° linear dual‐polarised suspended plate antenna is proposed. Isolation ( S ₁₂ , S ₂₁ ) between channels is improved by making extensions on suspended plates (SPs) 1–2 and inserting a vertical ungrounded vertical wall under SP‐1. The modified T‐type probes in this design provide better coupling and return losses ( S ₁₁ , S ₂₂ ) for wideband operation. Based on the numerical simulations and measurements, it is observed that 8.2 ± 0.5 dBi gain and 66° ± 6° symmetric azimuth and elevation radiation patterns are obtained. Return losses ≤ − 15 dB and isolation ≤ − 30 dB are achieved in the entire band. This antenna is suitable for base stations of mobile wireless communication systems (PCS, DCS and IMTS).