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تحسين اداء هوائي فيفالدي باستخدام المواد ما بعد المادية == Vivaldi Antenna Performance Enhancement Based On Metamaterials
Author name:
ادهم ربيع عزيز
Supervisor name:
زيد اسعد عبد الحسين | طه احمد عليوي
General topic:
Electrical, Electronic and Communications Engineering
Specific topic:
Electrical and Electronic Engineering
Degree:
Master
University:
Mustansiriyah University - College Of Engineering - Department Of Electrical Engineering
Language:
English
University location:
Baghdad
First pages:
34T516 - p.pdf
Abstract:
يتطرق البحث الى المتطلبات الاساسية في الانظمه اللاسلكيه الحديثة والضوابط المتوافقة مع امكانية اعادة التشكيل وقابلية التحديث مما ادى الى ان يصب مجال الدارسة في تحقيق تصميم هوائي يمكن له استيعاب ذلك. في هذه الدراسة، صمم هوائي مطوي على اساس هيكل فيفالدي مع | The urgent demands for a miniaturized, compatible, reconfigurable, updatable, and additive - able wireless communication systems for advanced handle held and portable electronics devices are rarely relaxed due to the inherent antenna limitations. In this study, developing a folded microstrip antenna based on a novel antipodal Vivaldi structure based metamaterial inclusions of single negative properties is proposed for wideband applications. Although, Vivaldi antennas show unlimited bandwidth, an acceptable directivity, small size, light weight and easy to fabricate, but, it suffers from low gain due to traveling surface waves effects and therefore, it cannot be embedded inside the integrated systems ,where, the radiation direction is in the end - fire that limits their use to the outdoor applications. Therefore, a remarkable attention was the first in the literature, is proposed in this thesis by introducing single negative metamaterials to the folded antipodal Vivaldi antenna structure. This work is developed based on a systematic approach which can be divided mainly into four parts : First of all, design a single negative metamaterial structure of a surface area 5×5 mm2 on an FR4 - Epoxy substrate. The unit cell properties are evaluated numerically and analytically, then, compared to the measurement. Second, a systematic approach is applied to design an antipodal Vivaldi antenna based flat profile of a corrugated shape with 50×38 mm2 on the FR4 - Epoxy substrate. Third, the best arrive of the flat geometry is folded on a hello Teflon substrate of an elliptical cross - sectional area. Fourth, the folded antenna structure is surrounded by a U - shaped single negative metamaterial array. The performance of the all proposed antennas are evaluated numerically, then, compared to their measurements in both S11 and radiation patterns. It is found that the antenna bandwidth has affected insignificantly by applying the metamaterial structures. However, with respect to the flat antenna model, the gain is increased generally by 6 dB as well as the radiation pattern is oriented to the broadside. It is worth to mention that the achieved enhancement in the gain is mostly attributed to the folded substrate and the metamaterial introduction. While, the bandwidth enhancement is mostly obtained from the folded antenna structure. The optimum structure shows a first mode around 1.4 GHz and the second one at 2.86 GHz, while, the flat antenna only one mode at 1.5 GHz is appeared.Finally, the HFSS, CST MWS, Matlab and ADS software packages are used in this thesis to study the unit cell performance and the antenna structure. Excellent agreements have been found between the simulated and measured results.
