IJE TRANSACTIONS B: Applications Vol. 31, No. 5 (May 2018) 576-585    Article in Press

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M. H. Neshati and Zahra S. Tabatabaeian
( Received: May 27, 2017 – Accepted: March 08, 2018 )

Abstract    In this paper sensitivity analysis of a wideband backward-wave directional coupler due to fabrication imperfections is done using Monte Carlo method. For using this method, a random stochastic process with gaussian distribution by 0 average and 0.1 standard deviation is added to the different geometrical parameters of the coupler and the frequency response of the coupler is estimated. The applied process must be done several times for converging Monte Carlo method. So, a large number of simulations is reqired for th coupler. This may take a long time if one uses High Frequency Structure Simulator (HFSS) as the siulation software. To decrease the required time of analysis, neural network model of the coupler incnjuction Mone Carlo is used. Results show that the bandwidth of the coupler, minimum return loss in passband and minimum isolation in passband won’t be change considerably using the sepecified value of random process. The measred results for a prototype of a backward wave coupler is presented, which confirm the results of the sensitivity analysis.


Keywords    backward-wave directional coupler, neural network, Monte Carlo method, probability density function, cumulative distribution function.


چکیده    در این مقاله، تحلیل حساسیت یک تزویج­کننده­ی پهن­باند روبه ­عقب در اثر خطای ساخت با استفاده از روش مونت کارلو انجام شده است. برای استفاده از روش مونت کارلو، خطایی تصادفی با توزیع گوسی با میانگین صفر و انحراف معیار 1/0 به ابعاد هندسی تزویج­کننده اضافه شده و برآوردی از پاسخ فرکانسی تزویج­کننده به­دست می­آید. برای همگرا شدن روش مونت کارلو، این کار باید دفعات زیادی تکرار شود. برای این تعداد زیاد بررسی، استفاده از نرم­افزار HFSS زمان زیادی نیاز دارد. برای کاهش زمان شبیه‌سازی، مدل شبکه عصبی تزویج­کننده به همراه روش مونت کارلو استفاده می­شود. نتایج نشان می­دهد که مشخصات مهم تزویج کننده شامل پهنای باند، حداقل تلفات بازگشتی در باند عبور و حداقل جداسازی پورت‌های مختلف در اثر خطای ساخت تغییر قابل ملاحظه­ای ندارند. هم‌چنین نتایج اندازه‌گیری مشخصات تزویج کننده برای یک نمونه ساخته شده تزویج کننده رو به عقب ارائه شده و مقایسه­ی نتایج اندازه‌گیری با نتایج شبیه­سازی، روش بررسی تحلیل حساسیت به‌کار رفته را تایید می‌کند.

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