Bilgilendirme: Kurulum ve veri kapsamındaki çalışmalar devam etmektedir. Göstereceğiniz anlayış için teşekkür ederiz.

Browsing by Author "Mezaal Dayyeni, Yaqeen Sabah"

Filter results by typing the first few letters
Now showing 1 - 1 of 1
  • Thumbnail Image
    Master Thesis
    New designs of microwave fractal resonators for modern wireless applications
    (2015) Mezaal Dayyeni, Yaqeen Sabah
    In this dissertation, new microstrip bandpass and bandstop filters based on fractal resonators have been presented in an attempt to construct filter designs with smaller size for almost modern wireless applications. The proposed bandpass filter structures have been generated based on Moore, Hilbert, Hilbert-zz and Sierpinski fractal geometries while the proposed bandstop filter is based on Hilbert Fractal resonators. The space-filling property and the self-similarity of the configurations related to the consecutive iteration levels of these fractal geometries have been found to create compact filter structures with accepted performance results.Narrowband compact Moore fractal filters from 2nd and 3rd iteration levels have been designed for 2.4 GHz band application using a relative dielectric constant of 10.8 and dielectric thickness of 1.27 mm with good performance results in their quasi elliptic responses. For 3rd iteration Moore bandpass filter, size reduction percentage as compared with 2nd iteration one resonating at the same frequency and using the same substrate material for 3rd iteration structure is 43% .The simulated and measured results are well-matched to each other . Stepped impedance Hilbert microstrip bandpass filters have designed with characteristics of compacted sizes and narrow band responses which are the requisites of recent wireless communication systems. These filters are built from two edge coupled resonators, each resonator has been achieved by applying step impedance resonator generator on 1st and 2nd iterations of Hilbert fractal resonators on each segment for each fractal iteration . They have been proposed for the ISM band applications at center frequency of 2.4 GHz using a substrate with a dielectric coefficient of 9.6 and thickness of 0.508 mm. Results show that these filters own satisfactory output frequency responses. Size reduction percentage as compared with 1st iteration stepped impedance Hilbert bandpass filter operating at similar frequency and using similar substrate material for 2nd iteration structure is 63.34% . New fractal design scheme based on Hilbert-zz curve has been used to produce compact microstrip bandpass filter .This fractal filter has been realized using two coupled resonators using additional coupling stubs .The material substrate has relative dielectric constant of 9 and thickness of 1.27 mm. Simulation graphs demonstrate that these filters possess good transmission and return loss features for the resultant frequency responses. It should be mentioned that Moore, stepped impedance Hilbert resonator and Hilbert-zz bandpass filters exhibit higher harmonics eliminations in out of passband regions of their frequency responses which are much desired properties in modern wireless communications. Miniaturized microstrip bandpass filters have been designed using Sierpinski fractal curves from 0th to 3rd iteration levels. The intended filter designs have been performed using dual-mode square slotted microstrip resonator in accordance with adopted fractal iterations. These microstrip bandpass filters have less bandwidth and sharper transmission responses than those of the single mode resonator and traditional square patch filter. Filter structures generating from the successive iterations of the applied fractal geometries exhibit a noticeably low insertion loss, and sharper response of about 1% fractional bandwidth as compared with the conventional microstrip square patch filter of 3% fractional bandwidth constructed at the same resonant frequency of 5.33 GHz and using substrate material of dielectric coefficient of 10.8 and thickness of 1.27 mm. A new dual-band microstrip bandpass filter has been designed using Peano fractal geometry at resonant frequencies of 2.25 GHz and 4.825 GHz using a substrate of a relative dielectric constant of 10.8 and thickness of 1.27 mm. The topology of this filter consists of dual edge coupled resonators constructed from 1st iteration of Peano fractal geometry. Simulated responses show that this filter has well frequency responses as well as dual bands gained which are highly requested in current communication systems. On the other hand, new designs of Wide Bandpass Filter (WBPF) and Narrow Bandstop Filter (NBSF) based on Hilbert fractal resonators have been investigated using Sonnet simulator. The frequency responses properties of the proposed filters have been studied to observe the corresponding broad bandpass and narrow bandstop behaviours at the frequency around 2GHz.Moreover, the phase dispersion and surface current density details about proposed filters have been presented and analyzed. The proposed fractal filters have been found to possess compact sizes with flexible designs in addition to good frequency responses.The modeling, simulation and performance evaluation have been performed using the method of moment (MoM) package Microwave Office 2009 from Advanced Wave Research (AWR) and a full-wave based electromagnetic simulator Sonnet software package which are very commonly used in electronics industry and research institutions.