Final questions - Microwaves 2

[Kamal]

:nar:

نخلي الموضوع ده من بابه كده إن شاء الله لأسئلة الامتحان ... ونرجو إن ما حدش يهظر في التوبيك عشان يبقي منظم سؤال وجواب ... وهشوف برده لو بشمهندس عمرو علاء كان فاضي (ما عندوش امتحانات ماجيستير ) وقدر يدخل يساعدنا

لو مش كده هنساعد بعض قدر الإمكان إن شاء الله

[فهد]

السؤال الاول

دلوقتى الجزء بتاع Review & Introduction هييجى فيه حاجه
انا اظن الدكتور كان مديه علشان نفهم الحاجات التانيه
زى مثلا الـــ Smith Chart علشان جزء الـــ Matching
وكمان الـــ S-Parameter علشان الـــ Even/Odd

انا بتكلم صح ولا غلطان
ممكن حد يوضح :think: ?

[Kamal]

لأ يا ريس ... أحيانا بييجي فيه حاجات ... أهم الحاجات اللي لاحظتها اتسال عليها

ال concept بتاع TEM Modes هتلاقيه في المحاضرة ... مش في السليدز .. سال عنها في امتحان 2009 .. وسال معاها علي field configuration واضح انه بيحبه ..

والحتة التانية اللي جاب عليها مسالة حلوة في 2006 ... بتاع telegrapher equations proof ... غيرلك الconfiguration وقالك اثبت من الاول وقولي الفرق بين الحالتين ..

ممكن زي مانت ما بتقول ال S parameters و Smith chart ما يسالش عنهم فعلا في الشبتر ده لانه كان مديهم عشان الشباتر التانية ... بس خلي بالك ان مش كل الشبتر كده ... ممكن يسالك كمان في حتة Non TEM Modes .. لما كان بيطلع C1 & C2 ديه حتة ممكن يسال عنها ليه لأ

[فهد]

طيب ممكن حد يرفع المحاضرات
على الاقل بتاعت الشابتر الاول ؟

[Kamal]

امممممممم .. هحاول والله يا عارف .. بس مش عارف الوقت هيسعفني ولا لأ لان السكانر بيجنني شوية هو والبرنامج بتاعه ... ربنا ييسر .. هجتهد إني أرفعهم النهاردة وانا بذاكر إن شاء الله

[nadim]

طيب ممكن حد يرفع المحاضرات
على الاقل بتاعت الشابتر الاول ؟

لا يا باشا
المادة ديه تعتمد على مجهودك الذاتي
وبعدين الموضوع مش صعب قوي لانك عندك slides ومرجع Pozar الاتنين ماشيين in parallel
:):)

[فهد]

لا يا باشا
المادة ديه تعتمد على مجهودك الذاتي
وبعدين الموضوع مش صعب قوي لانك عندك slides ومرجع Pozar الاتنين ماشيين in parallel
:):)
ما هو كمال هيحاول
لو قدر يبقى كويس
وعلى العموم شكرا :)

[nadim]

هو احنا خدنا إيه في section 2.6
generators & load mismatches
؟؟؟

[planète bleue]

خلوا بالكوا من إثباتات ال kuroda identities عشان أنا لاقيتني كاتبة أن الدكتور ممكن يقولي اثبت واحدة منهم واستخدمها

[فهد]

خلوا بالكوا من إثباتات ال kuroda identities عشان أنا لاقيتني كاتبة أن الدكتور ممكن يقولي اثبت واحدة منهم واستخدمها

لأ :Angry: كفاية اثباتات
على العموم تشكرى يا بشمهندسه

[planète bleue]

متخافش والله ده أمور

[فهد]

متخافش والله ده أمور

انا اكتر حاجه مريحانى ان الماده تقريبا مش محتاجه حفظ
خالص
بس ما دام اثبات واحد يبقى خلاص مفيش مشاكل :)

وشكرا لحضرتك
لانك فكرتينا

[planète bleue]

حضرتك بص صفحة 408 وهي هي نفس الخطوات .. أنا عملت واحدة .. وطلعت الحمد لله .. استحليت اللعبة وعملت التانية وطلعت برده الحمد لله :D

[فهد]

حضرتك بص صفحة 408 وهي هي نفس الخطوات .. أنا عملت واحدة .. وطلعت الحمد لله .. استحليت اللعبة وعملت التانية وطلعت برده الحمد لله :D

ديه شكلها سهل على كده
طيب كويس
الحمد لله (:

[AhmedElSayed]

طيب ممكن حد يرفع المحاضرات
على الاقل بتاعت الشابتر الاول ؟

آه ياريت و خصوصاً أول محاضرتين .. و شكراً مقدما (:

[فهد]

آه ياريت و خصوصاً أول محاضرتين .. و شكراً مقدما (:
لأ يا ريت الـــ introduction كلها
لو سمحتم

[فهد]

فى الجزء بتاع الـــ Filter design
هو احنا المفروض نعرف كل نوع ولا ايه
وكمان قبل الامثله اللى الدكتور اديهالنا
كنا فى شويه رسومات
هى مهمه

ولا المهم انى اعرف احل المسائل زى اللى البشمهندس حلها فى السكشن الاخير
منتظر الاجابه شرورى

[فهد]

لو انا فاهم من الـــ slides و من السكشن
هل لازم ابص فى Pozar :think: ?

[فهد]

انا عارف ان الاسئله كترت
بس معلش
هى اصلا اسئله ساهله

المهم
دلوقتى ممكن حد يقول ايه اللى احنا المفروض نعرفه فى جزء الــــ high/Band Pass Filter :think: ?

مستنى (:

[nadim]

لو انا فاهم من الـــ slides و من السكشن
هل لازم ابص فى Pozar :think: ?

Pozar مهم ..ليه؟؟
عشان تلات حاجات :
أول حاجة : شرحه كويس
تاني حاجة : الدكتور بيشتغل منه وعامل ال slides منه
تالت حاجة : احنا معندناش شيت فا هنحل منه
:):)

[nadim]

انا عارف ان الاسئله كترت
بس معلش
هى اصلا اسئله ساهله

المهم
دلوقتى ممكن حد يقول ايه اللى احنا المفروض نعرفه فى جزء الــــ high/Band Pass Filter :think: ?

مستنى (:

تفهم ال concept
بس كده :):)

[فهد]

شكرا يا عمنا :)

[planète bleue]

أنا فيه حاجة لفت معايا كدة .. بس عايزة أتأكد أنا فاهمة صح ولا لأ ..

في صفحة 310 .. جزء ال circulator , لما جه رسم الرسمة وجاب ال S matrix

لو مسكنا رقم a مثلا

عندي S12=0

S12=V1-/V2+ , so V1-=0

هل معنى كدة أن ال wave مش هتنعكس على port 1 فبالتالي هتكمل من 1 إلى 2

ولا ايه ؟

[yousef]

....

[فهد]

لو سمحتى يا بشمهندسة عصفور الجنة (http://www.h3sonline.com/forums/member.php?u=304)
مادام انتِ اللى قلتى على اثبات الـــ kuroda identitie :)
تقولى ازاى احنا بنجيب الخطوة اللى رقم ( 8.80a ) فى المرجع صافحة 408
يعنى ازاى بنضرب الـــ two matrix قى بعض

انا مستنى اهه وشكرا مقدما

[nadim]

عمو فهد

ال link ده هيقولك ازاي تضرب two matrices في بعض

http://mathworld.wolfram.com/MatrixMultiplication.html

:):)

[planète bleue]

no that means matched

يعني الكلام اللي فوق ده ملهوش علاقة بال matching !

[yousef]

sorry my mistake
it means that if you inserted signal from 2 it will not go out on 1

[planète bleue]

in page 320, eq.7.35

how did he get gama !

and how did he get V1e=-j*Vo*root(2) !

[amr alaa]

in page 320, eq.7.35

how did he get gama !

and how did he get V1e=-j*Vo*root(2) !
السلام عليكم و رحمة الله و بركاته

If we are standing in the transmission line and look into port 1, then we will end up with a T.L with c/cs impedance of root(2)*Zo and terminated with impedance = 2*Zo. The reflection coefficient = (Z_L-Zo)/(Z_L+Zo)=(2*Zo-root(2)*Zo)/(2*Zo+root(2)*Zo). which is the equation given then substitute back in 7.34 to get V1_e

[amr alaa]

From the level of the questions, I do not know if this the quiet before the storm or you people are really understanding the subject :lol:. Anyway, no body asked for office hours till now so I think I can manage the questions in this forum without the need for you to come to college and ask me personally

My regard
Amr Alaa

[Kamal]

ربنا يكرمك يا بشمهندس علي دخول حضرتك ومتابعتك .. انا بصراحة ما رضيتش اتصل بحضرتك عشان عارف إن حضرتك عندك امتحانات الماجيستير .. ربنا يوفقك

[momen]

could you please upload the matching slides

[amr alaa]

could you please upload the matching slides

I think it is uploaded somewhere in this forum. It was not that much, and if you remember we did most of the work on the white board

[فهد]

ربنا يكرمك يا بشمهندس علي دخول حضرتك ومتابعتك .. انا بصراحة ما رضيتش اتصل بحضرتك عشان عارف إن حضرتك عندك امتحانات الماجيستير .. ربنا يوفقك

طيب اخبار المحاضرات
هترفعها
ولا ايه ؟

[فهد]

عمو فهد

ال link ده هيقولك ازاي تضرب two matrices في بعض

http://mathworld.wolfram.com/MatrixMultiplication.html

:):)
شكرا

[AhmedElSayed]

I think it is uploaded somewhere in this forum. It was not that much, and if you remember we did most of the work on the white board


He's asking about the slides that contained 4 figures like this one

http://www.rfcafe.com/references/electrical/images/Simple%20Visio%20Smith%20Chart%20-%20Forbidden%20UpLeft.png

[Kamal]

طيب اخبار المحاضرات
هترفعها
ولا ايه ؟

المشكلة إني متأخر في المذاكرة فعاوز ألحق أوصل لجزء معين .. إن شاء الله لو فيه وقت هرفعهم ...

[Mido AG]

ya gma3a hya el STEPPED IMPEDANCE LPF m3ana

[Kamal]

هو انا لسه كنت معدي عليها .. الدكتور ما كانش قال حاجة خالص عنها !! ..

يا ريت لو حد يعرف حاجة تانية يقول

[mo7sen]

howa proof l field analysis of stripline 3alena wla la2,,wkuroda identity 7efz wla given fl exam,,thxx alott:)

[planète bleue]

حد جرب يا جماعة يطلع ال ABCD matrix بتاعة ال 180 hybrid .. مش راضية تطلع معايا :sad:

[Kamal]

سؤال لبشمهندس عمرو علاء


لو حد عارف الإجابة يقول برده .. ما فيش مشاكل يعني :)

في امتحان 2006 مسألة الفلتر .. اخر مطلوب .. اداني epsilon effective .. وطلب مني اجيب Length of sections .... إيه قصده بطول السكشن .. مش هو مفترض ثابت لكل الستركشر وبيساوي lambda / 4 ؟؟


في امتحان 2009 كان اداني برده epsilon r .. بس طلب مني الابعاد بال مم .. مفترض ديه هنعملها زي السكشن عادي .. هجيب W/d وانا عارف epsilon r ... هعوض في القانون 3.195 هجيب epsillon effective .. تمام كده ؟ والابعاد اللي هجيبها بمعلومية h اللي مديهالي هي W بس ..

إيه بقي فرقها عن مسالة 2006 ... ؟

[فهد]

سؤال لبشمهندس عمرو علاء


لو حد عارف الإجابة يقول برده .. ما فيش مشاكل يعني :)

في امتحان 2006 مسألة الفلتر .. اخر مطلوب .. اداني epsilon effective .. وطلب مني اجيب Length of sections .... إيه قصده بطول السكشن .. مش هو مفترض ثابت لكل الستركشر وبيساوي lambda / 4 ؟؟


في امتحان 2009 كان اداني برده epsilon r .. بس طلب مني الابعاد بال مم .. مفترض ديه هنعملها زي السكشن عادي .. هجيب W/d وانا عارف epsilon r ... هعوض في القانون 3.195 هجيب epsillon effective .. تمام كده ؟ والابعاد اللي هجيبها بمعلومية h اللي مديهالي هي W بس ..

إيه بقي فرقها عن مسالة 2006 ... ؟

ايه ده هو انت مش عارف
انا كنت هسألك عليها

طيب لو حد يعرف يا ريت يجاوب

[planète bleue]

بشمهندس عمرو .. أنا قلقانة أوي من ال chapter بتاع ال even وال odd analysis .. حاجات قليلة بتطلع معايا صح :(

بالنسبة لل prooves بتاعة hybrid مثلا .. لو طلعت ال ABCD غلط .. درجة المسأله كلها هتضيع ؟ :sad:

مشكلة بجد :(

[amr alaa]

سؤال لبشمهندس عمرو علاء


لو حد عارف الإجابة يقول برده .. ما فيش مشاكل يعني :)

في امتحان 2006 مسألة الفلتر .. اخر مطلوب .. اداني epsilon effective .. وطلب مني اجيب Length of sections .... إيه قصده بطول السكشن .. مش هو مفترض ثابت لكل الستركشر وبيساوي lambda / 4 ؟؟


في امتحان 2009 كان اداني برده epsilon r .. بس طلب مني الابعاد بال مم .. مفترض ديه هنعملها زي السكشن عادي .. هجيب W/d وانا عارف epsilon r ... هعوض في القانون 3.195 هجيب epsillon effective .. تمام كده ؟ والابعاد اللي هجيبها بمعلومية h اللي مديهالي هي W بس ..

إيه بقي فرقها عن مسالة 2006 ... ؟

In 2006 exam, you are correct, all the sections length equal to lamda/4 but this is the electrical length, he was asking about the physical length . You can calculate it from the relation:
betal *l= lamda/4 -->((omega*sqrt(epsilon_eff))/c)*l = lamda/4
This is Wrong
Both the physical length and electrical length are lengths and their units are in (m). However, in electrical length the length is given in terms of lamda. So to know the actual length you need to know the value of lamda at the frequency you are operating at. The equation you should use is:
L = lamda/4 and since C = f*lamda --> L = C/(4*f*sqrt(epsilon_eff)) to account for the velocity in the medium and f is the operating frequency you are operating at.

Sorry for this mistake, I was studying yesterday and it seems that I was not focusing enough.

In exam 2009,he did not give you epsilon_r.So, I think you are talking about exam 2007-2008. The first part (Determine epsilon_eff and the dimensions of a 50Ohm line) is solved as you said. But I want to note a point here, in part (4) when he asked about the final dimensions in mm. Remember that each lamda/4 section will have its own c/cs impedance and hence its own W/d and hence its own epsilon_eff. So, you need to redo what you have done in part(1) for every section with different c/cs impedance. This is a little impractical but in my opinion you need to do it once for one section and get its physical length and say that similarly we can do the same for other sections. Do not waste your time in completing the problem to the final answer

My regard
Amr Alaa

[amr alaa]

Here is the link to "impedance matching section slides". I could not upload it on the forum because of some weird errors. The link is on rapidshare
http://rapidshare.com/files/399185384/Impedance_Matching_Networks.rar.html

could anyone upload it on the site please

[فهد]

فعلا المنتدى فيه مشكله فى قاعده البيانات
انا رفعت الملف على الـــ mediafire.com
http://www.mediafire.com/?jzhdnyozzhz

[فهد]

In 2006 exam, you are correct, all the sections length equal to lamda/4 but this is the electrical length, he was asking about the physical length . You can calculate it from the relation:
betal *l= lamda/4 -->((omega*sqrt(epsilon_eff))/c)*l = lamda/4

In exam 2009,he did not give you epsilon_r.So, I think you are talking about exam 2007-2008. The first part (Determine epsilon_eff and the dimensions of a 50Ohm line) is solved as you said. But I want to note a point here, in part (4) when he asked about the final dimensions in mm. Remember that each lamda/4 section will have its own c/cs impedance and hence its own W/d and hence its own epsilon_eff. So, you need to redo what you have done in part(1) for every section with different c/cs impedance. This is a little impractical but in my opinion you need to do it once for one section and get its physical length and say that similarly we can do the same for other sections. Do not waste your time in completing the problem to the final answer

My regard
Amr Alaa




شكرا يا بشمهندس
الموضوع دلوقتى اوضح :)

[nadim]

Example 8.3 page 400

Are the final answers correct
???

[planète bleue]

Example 8.3 page 400

Are the final answers correct
???

yes, just don't forget that u substitute with omega not freq, so u have to multiply by 2pi

[فهد]

طلب يا جدعان

دلوقتى انا تايه فى الـــ Review & Introduction
مش عارف ايه الحاجات المهمه
ممكن لو حد زاكرها يقول :think: ?

[nadim]

yes, just don't forget that u substitute with omega not freq, so u have to multiply by 2pi

Thanks :)

[nadim]

طلب يا جدعان

دلوقتى انا تايه فى الـــ Review & Introduction
مش عارف ايه الحاجات المهمه
ممكن لو حد زاكرها يقول :think: ?

اهم الحاجات هي:

TL
Smith Chart
Network Parameters
Voltage & Current Definition

الدكتور معملش معانا أي field analysis لاي waveguide فـأنا أعتقد أن كم الرياضة المهول ده مش علينا
:):)

[planète bleue]

in section of smith chart slides

slide 11

بشمهندس عمرو هنا أعتقد عكس ال solution لما جه يجيب ال length لكل stub

صح ؟

[planète bleue]

in section of smith chart slides

slide 11

بشمهندس عمرو هنا أعتقد عكس ال solution لما جه يجيب ال length لكل stub

صح ؟

لا تمام مش عاكسها ولا حاجة .. أنا اللي لفت معايا :petlya35ch:

[AhmedElSayed]

في آخر slides يعني إيه forbidden region ؟؟ و آخد بالي منها إزاي في الإمتحان و لا أحل زي pozar و خلاص ؟؟

[Kamal]

In 2006 exam, you are correct, all the sections length equal to lamda/4 but this is the electrical length, he was asking about the physical length . You can calculate it from the relation:
betal *l= lamda/4 -->((omega*sqrt(epsilon_eff))/c)*l = lamda/4

In exam 2009,he did not give you epsilon_r.So, I think you are talking about exam 2007-2008. The first part (Determine epsilon_eff and the dimensions of a 50Ohm line) is solved as you said. But I want to note a point here, in part (4) when he asked about the final dimensions in mm. Remember that each lamda/4 section will have its own c/cs impedance and hence its own W/d and hence its own epsilon_eff. So, you need to redo what you have done in part(1) for every section with different c/cs impedance. This is a little impractical but in my opinion you need to do it once for one section and get its physical length and say that similarly we can do the same for other sections. Do not waste your time in completing the problem to the final answer

My regard
Amr Alaa




طيب يا بشمهندس .. هو فيه حاجة ملغبطاني جامد جدا ...

الفرق بين Electrical Length & Physical Length

دلوقتي انا لما كنت عند تردد omega C .. كنت بشتغل علي طول lambda /8 ...عشان لما اطبق القانون ده
tan(beta * l ) = tan((2*pi/lambda) * (lambda/8)) = tan (pi / 4) =1


طيب لما اشتغل عند تردد
2 * omega C

ليه قولت الطول هيبقي
lambda /4

يعني لو هطبق علي نفس المبدأ اللي فوق ده فلو التردد زاد الطول هيقل !! ..

وانهي طول اللي انا بتكلم عليه

Physical or Electrical ??

وايه اصلا معني الطول ال electrical
بحاول افهمه وادورله علي حاجات بس مش متخيله كويس ...

أنا بجد حاسس إن الحتة ديه تايه فيها ومش عارف افهمها منين ولا المرجع شارحها ولا حالل عليها ولا لاقي حاجة علي النت شارحاها كويس

[planète bleue]

in double stub matching

in pozar page 237 example 5.3

حسابات ال stub lengths دي صح !

يا إما أنا اللي مش فاهمة ازاي تتحسب .. :sad:

[Mido AG]

l2 and l1' ma3kosen

[planète bleue]

طيب أنا الأرقام كلها بايظة عندي !

مش المفروض أني بحسب ال L من نقطة ال zero وأمشي مع ال generator لغاية ال y1 مثلا عشان أجيب ال L1 ??

[nadim]

طيب أنا الأرقام كلها بايظة عندي !

مش المفروض أني بحسب ال L من نقطة ال zero وأمشي مع ال generator لغاية ال y1 مثلا عشان أجيب ال L1 ??

سيبك من ال Slides عشان أعتقد أن فيها غلط في ال example ده
شوفي ال example إللي في pozar صفحة 229
هو حاللها صح
:):)

[planète bleue]

ماشي هشوفه بس المشكلة أنا كان نفسي أحل على ال double stub ومفيش عليها مسألة للأسف في السيكشن .. :)

[yousef]

for y1 the distance from the load to the y1
is b1 =y1 - yl notice that it should be yl-y1 but since i am adding it is value so it will be y1- yl
then move from the zero admittance towards the generator to get the b1 value
that will give l1 = 0.146 and l1' = 0.410
for the y2 since going to the center
it is moving from the zero admittance to it - value
since we are adding that value

[planète bleue]

good but it gives me l1=0.164 *lamda !

and l1'=0.048 !!!

طيب يا بشمهندس المفروض ال y1 عادي بنجيبها أننا بنمشي من ال Yl على constant r لغاية ما نقاطع دايرة ال 1+jb بعد ما لفيناها ..

مضبوط كدة ؟

[yousef]

yes this is the point
but not the value of the added admittance
for l1' notice it should be else
since b1' is negative i.e. in the lower half thus making it different value
and make it close to 0.5

[planète bleue]

هيييييييييييه طلعت خلاص تمام كدة ألف شكر :)

[planète bleue]

yes this is the point
but not the value of the added admittance
for l1' notice it should be else
since b1' is negative i.e. in the lower half thus making it different value
and make it close to 0.5

أيوة تمام أدركت الموقف .. :c:

يعني احن لما بنكون على ال rotated 1+jb circle بناخد القرايات بتاعة ال L عند الفرق بين الYl و ال Y1 سواء بالموجب أو بالسالب ..

إنما على g=1 circle عادي هناخد قيمة ال admittance هي ال L سواء بالموجب أو بالسالب برده ..

صح كدة ؟ :)

[planète bleue]

كدة طلعت بس على فكرة فعلا ال l1' and l2 متبدلين

[فهد]

لو سمحت يا كمال لو انت فهمت السؤال اللى كنت سألته للبشمهندس
تقولنا براحه كده انت فهمت ايه

علشان انا قرات الرد ومش فاهم حاجه تقريبا

ممكن :think: ?

[AhmedElSayed]

in the example in page 340, he used the formula C = Epsilon * Area / separation to get the capacitance per unit length !!

this formula should give the total capacitance not capacitance per unit length, shouldn't it ??!!


ah sorry, he used C = Epsilon * Width / Separation

[AhmedElSayed]

Question:

In LPF, do we place the series inductor first or the shunt capacitor, or it doesn't matter ???

[AhmedElSayed]

Question:

In the equal ripple method, how can we convert the ripple level (1+K*K) to/from dB ??

do we use 20 log(1+k*k) or 10 log (1+k*k) ?? .. thanks

[planète bleue]

أعتقد 10 log .. احن بنتعامل بالـ power عادي ..

[planète bleue]

what's the difference between the electrical and physical port ?

وهل علينا ال dispersion وال losses وال slotlines في جزء ال planar TL ?

[yousef]

ما اعتقدش علينا
الفرق
electrical length is with lamda i.e. how many lamdas
physical length is with meters i.e. you can get it by putting lamda at the wanted frequency
as far as i know
:lol:

[فهد]

فى سؤال بييجى كتير فى الامتحانات بيسأل عن الـــ rat-race coupler
هو ده أصلا علينا :think: ?

ضرورى حد يقول علشان الحق اذاكرة

[AhmedElSayed]

أيوة يا عم فهد علينا .. ده من أهم الحاجات اللي لازم تتذاكر على ما أظن

[فهد]

طيب دلوقتى فى الامتحان سنه 2008/2009
الاسؤال التانى
طلب اثبات الـــ wilkison من غير ما يعطى الرسمه بتاعته
هو احنا المفروض نحفظها ولا ايه

مع العلم ان السنه ديه كان الامتحان Open book

مستنى الاجابه
مع الشكر والامتنان مقدما (:

[amr alaa]

ما اعتقدش علينا
الفرق
electrical length is with lamda i.e. how many lamdas
physical length is with meters i.e. you can get it by putting lamda at the wanted frequency
as far as i know
:lol:

This exactly the answer. Normally, microwave structures are given in terms of lamda. So that they can operate at any required frequency . Meaning that you can choose the center frequency you want to operate at (W_o). Once it is chosen then you will need to determine the physical length because this is what will be really manufactured. As you deviate from this frequency then the physical length you specified will not be the same electrical length as before. For example, if at certain W_0 you needed an electrical length of lamda/4 and got the equivelant physical length at that W_o and manufactured this device with tha physical length. Then at 2*W_o the new_lamda = old_lamda/2 so that the specified physical length will now represent lamda/2.
Mathematically speaking,
@ W_o we have L=lamda/4 = c/(4*f_o) which is a physical length
now we want to calculate how much lamdas this physical length represents @ 2*W_o
L/new_lamda = (c/(4*f_o)) / (c/(2*f_o)) = 0.5 --> L = new_lamda/2
I hope this clear
Please look at my previous post regarding the exam of 2006 as THERE WAS A MISTAKE

[vahnlle]

Question:




In LPF, do we place the series inductor first or the shunt capacitor, or it doesn't matter ???


hey ya ahmad , when we want to implement in all shunt stubs , its easier to put a seires inductor first then a cap , then another seires inductor maslan ( n=3) , so its easy to apply koruda identity ... just a dd 2 unit elements and in one shot u will get the designe u want ..................... but both circuits of the prototype have the same responce :)

[vahnlle]

hey eng amr ..

i am asking about the 1st question in exam 2009 ( what is the field config. and what are the independent DC soln ) ?


other question ... 1st Q in 2006 ... how can i use the directional coupler to measure both S11 and S12 simultanousy ??


:) thank U

[amr alaa]

سؤال لبشمهندس عمرو علاء


لو حد عارف الإجابة يقول برده .. ما فيش مشاكل يعني :)

في امتحان 2006 مسألة الفلتر .. اخر مطلوب .. اداني epsilon effective .. وطلب مني اجيب Length of sections .... إيه قصده بطول السكشن .. مش هو مفترض ثابت لكل الستركشر وبيساوي lambda / 4 ؟؟


في امتحان 2009 كان اداني برده epsilon r .. بس طلب مني الابعاد بال مم .. مفترض ديه هنعملها زي السكشن عادي .. هجيب W/d وانا عارف epsilon r ... هعوض في القانون 3.195 هجيب epsillon effective .. تمام كده ؟ والابعاد اللي هجيبها بمعلومية h اللي مديهالي هي W بس ..

إيه بقي فرقها عن مسالة 2006 ... ؟

In 2006 exam, you are correct, all the sections length equal to lamda/4 but this is the electrical length, he was asking about the physical length . You can calculate it from the relation:
betal *l= lamda/4 -->((omega*sqrt(epsilon_eff))/c)*l = lamda/4
This is Wrong
Both the physical length and electrical length are lengths and their units are in (m). However, in electrical length the length is given in terms of lamda. So to know the actual length you need to know the value of lamda at the frequency you are operating at. The equation you should use is:
L = lamda/4 and since C = f*lamda --> L = C/(4*f*sqrt(epsilon_eff)) to account for the velocity in the medium and f is the operating frequency you are operating at.

Sorry for this mistake, I was studying yesterday and it seems that I was not focusing enough.

In exam 2009,he did not give you epsilon_r.So, I think you are talking about exam 2007-2008. The first part (Determine epsilon_eff and the dimensions of a 50Ohm line) is solved as you said. But I want to note a point here, in part (4) when he asked about the final dimensions in mm. Remember that each lamda/4 section will have its own c/cs impedance and hence its own W/d and hence its own epsilon_eff. So, you need to redo what you have done in part(1) for every section with different c/cs impedance. This is a little impractical but in my opinion you need to do it once for one section and get its physical length and say that similarly we can do the same for other sections. Do not waste your time in completing the problem to the final answer

My regard
Amr Alaa

[amr alaa]

in double stub matching

in pozar page 237 example 5.3

حسابات ال stub lengths دي صح !

يا إما أنا اللي مش فاهمة ازاي تتحسب .. :sad:

You are right, the lengths are reversed. The correct solution is shown in figure 5.9 page 239

[amr alaa]

Question:

In LPF, do we place the series inductor first or the shunt capacitor, or it doesn't matter ???


We commented about this point in the section. They are both equivalent . However, if it is required to realize the filter using only shunt stubs then choosing he inductor first will facilitate the solution especially if the filter order is three. If it is four then it will not matter if you started with inductor or capacitor (check the example we did in the section

[amr alaa]

Question:

In the equal ripple method, how can we convert the ripple level (1+K*K) to/from dB ??

do we use 20 log(1+k*k) or 10 log (1+k*k) ?? .. thanks


This is a good point. It is 10*log(1+k^2), nice question

[amr alaa]

what's the difference between the electrical and physical port ?

وهل علينا ال dispersion وال losses وال slotlines في جزء ال planar TL ?

A physical port is just a physical port :lol:. It is assigned with a physical existing terminal. We assign to each propagating mode from this port an electrical port
For example if we have a rectangular wave guide operating with three modes. Then the physical terminal is the physical port and we assign to this port three electrical ports for the three propagating modes

[AhmedElSayed]

hey ya ahmad , when we want to implement in all shunt stubs , its easier to put a seires inductor first then a cap , then another seires inductor maslan ( n=3) , so its easy to apply koruda identity ... just a dd 2 unit elements and in one shot u will get the designe u want ..................... but both circuits of the prototype have the same responce :)

asl the 2 circuits in the reference are confusing, the one with a voltage source has a shunt cap. after the generator resistance, and the one with a current source has a series conductor after the generator conductance so I thought the response might change if I changed the order of the elements. but from what you said I understand that it won't matter and g1 for instance could be assigned to a cap. or to an inductor without affecting the response. but its better to start with an inductor to use the first kurod's identity.. right ?

could Bm. Amr confirm that ??

I've just read your reply (:

----
and concerning Kuroda's 3rd and 4th identity .. how could we implement the transformer ??:wacko1:

[Kamal]

بشمهندس عمرو

بالنسبة للمطلوب الأول في المسألة الأولي في امتحان 2009

كان طلب إننا نرسم ال field configuration في حالة coplanar WG ... عدد ال modes بيساوي 3 ... شكل المودز ديه هتبقي عاملة ازاي ورسمتهم هتطلع ازاي ... احنا اللي نعرفه

even & odd configuration لكن مش عارف ايه المقصود بالسؤال ده

[amr alaa]

فى سؤال بييجى كتير فى الامتحانات بيسأل عن الـــ rat-race coupler
هو ده أصلا علينا :think: ?

ضرورى حد يقول علشان الحق اذاكرة

Yes of course. Although Dr.Amr, did not explain it in the lectures but we solved similar examples in the section.
Please people make sure that you study the wilkinson power divider page 318, the quadrature hybrid page 333, coupled line directional couplers page 337 till page 344, the 180 hybrid or (rat-race) page 352
There is a great chance that one of them will be in the exam tomorrow isA
You can study them from the reference or from the Dr sildes

[elec-tric]

طيب يا بشمهندس .. هو فيه حاجة ملغبطاني جامد جدا ...

الفرق بين Electrical Length & Physical Length

دلوقتي انا لما كنت عند تردد omega C .. كنت بشتغل علي طول lambda /8 ...عشان لما اطبق القانون ده
tan(beta * l ) = tan((2*pi/lambda) * (lambda/8)) = tan (pi / 4) =1


طيب لما اشتغل عند تردد
2 * omega C

ليه قولت الطول هيبقي
lambda /4

يعني لو هطبق علي نفس المبدأ اللي فوق ده فلو التردد زاد الطول هيقل !! ..

وانهي طول اللي انا بتكلم عليه

Physical or Electrical ??

وايه اصلا معني الطول ال electrical
بحاول افهمه وادورله علي حاجات بس مش متخيله كويس ...

أنا بجد حاسس إن الحتة ديه تايه فيها ومش عارف افهمها منين ولا المرجع شارحها ولا حالل عليها ولا لاقي حاجة علي النت شارحاها كويس

i became confused from your question ,kamal.
as i know that all lengths in the filter structure must be lamda/8
i don't know from where lamda/4 came from

[vahnlle]

true , this came from richards indentity .... it must be lamba \ 8

[vahnlle]

plz eng amr .. take a look for my Q .... it at the top :)

[AhmedElSayed]

what's meant by a matched port ??
does this mean its c/cs impedance should be zo ???

[فهد]

Yes of course. Although Dr.Amr, did not explain it in the lectures but we solved similar examples in the section.
Please people make sure that you study the wilkinson power divider page 318, the quadrature hybrid page 333, coupled line directional couplers page 337 till page 344, the 180 hybrid or (rat-race) page 352
There is a great chance that one of them will be in the exam tomorrow isA
You can study them from the reference or from the Dr sildes



خلاص انا هركزفيهم وربنا يسهل وتيجى حاجه منهم

[فهد]

Yes of course. Although Dr.Amr, did not explain it in the lectures but we solved similar examples in the section.

انا مش لاقى حاجه عن الـــ rat-race coupler فى السكشن للاسف

[فهد]

طلب غريب شويتين
لو انا امامى نص ساعه اذاكر بسرعه الـــ Review & Intro
ايه اهم الحاجات من وجهه نظر حضرتك يا بشمهندس amr alaa (http://www.h3sonline.com/forums/member.php?u=1721)

فعلا السؤال ده مهم جدا بالنسبه ليا
منتظر الاجابه (:

[Kamal]

i became confused from your question ,kamal.
as i know that all lengths in the filter structure must be lamda/8
i don't know from where lamda/4 came from

سيبك من كلامي كنت بخطرف ... اقرا ردين بشمهندس عمرو الاخيرين

[amr alaa]

بشمهندس عمرو

بالنسبة للمطلوب الأول في المسألة الأولي في امتحان 2009

كان طلب إننا نرسم ال field configuration في حالة coplanar WG ... عدد ال modes بيساوي 3 ... شكل المودز ديه هتبقي عاملة ازاي ورسمتهم هتطلع ازاي ... احنا اللي نعرفه

even & odd configuration لكن مش عارف ايه المقصود بالسؤال ده

Attached is the field configuration figure
http://h3sonline.com/forums/attachment.php?attachmentid=3948&stc=1&d=1276629381

[amr alaa]

hey eng amr ..

i am asking about the 1st question in exam 2009 ( what is the field config. and what are the independent DC soln ) ?


other question ... 1st Q in 2006 ... how can i use the directional coupler to measure both S11 and S12 simultanousy ??


:) thank U

I think that the question regarding the directional coupler is in the slides regarding the RF measurements. You may check if you have the slides

[amr alaa]

طلب غريب شويتين
لو انا امامى نص ساعه اذاكر بسرعه الـــ Review & Intro
ايه اهم الحاجات من وجهه نظر حضرتك يا بشمهندس amr alaa (http://www.h3sonline.com/forums/member.php?u=1721)

فعلا السؤال ده مهم جدا بالنسبه ليا
منتظر الاجابه (:

I do not feel comfortable answering these type of questions. Because I may say to you something is not important and you might find it tomorrow in the exam

[vahnlle]

ok , another question .. about the circulator ... in 2 exams .. what happens to circulator when one of the ports is matched ( i think the function is ISOLATOR ) , and what happens when 1 port is short circuit ? and what happens if one port is open circuit ??

thanks

[amr alaa]

ok , another question .. about the circulator ... in 2 exams .. what happens to circulator when one of the ports is matched ( i think the function is ISOLATOR ) , and what happens when 1 port is short circuit ? and what happens if one port is open circuit ??

thanks

You are correct for the isolator case. For open circuit case (gamma = 1) so the resulting two port network will have S21 = S12 = 1, it is simple transmission line. For short circuit case (gamma =-1) you will have S21 = -1 and S21 = 1 (or viceversa depending on the position of the short circuit

[فهد]

You are correct for the isolator case. For open circuit case (gamma = 1) so the resulting two port network will have S21 = S12 = 1, it is simple transmission line. For short circuit case (gamma =-1) you will have S21 = -1 and S21 = 1 (or viceversa depending on the position of the short circuit



شكرا على الاجابه
فعلا الحته ديه كانت ملغبطانى

[فهد]

Attached is the field configuration figure
http://h3sonline.com/forums/attachment.php?attachmentid=3948&stc=1&d=1276629381




شكرا بس انهى الــ Even وانهى الـــ Odd ?

[planète bleue]

بشمهندس ممكن باختصار كدة تقولي ازاي أقرا قيمة ال gamma من على smith chart

[فهد]

بشمهندس ممكن باختصار كدة تقولي ازاي أقرا قيمة ال gamma من على smith chart

طيب كمان ممكن حضرتك تقول باختصار برضه
ايه الحاجات اللى المفروض نعرف نطلعها من smith chart ؟

[vahnlle]

شكرا بس انهى الــ Even وانهى الـــ Odd ?



there is no even and odd here .... just various ways to do 3 independent ways to get DC solutions .......... that are not a linear combination of others ( remember 3ammak ASHRAF beta3 el reyada )

lol

[amr alaa]

بشمهندس ممكن باختصار كدة تقولي ازاي أقرا قيمة ال gamma من على smith chart

To get the amplitude of gamma, measure the distance from the center of smith chart to the point representing the load and divide it by the radius of the Smith chart it self. the phase of gamma is simply the angle measured from the X-axis

[Kamal]

Attached is the field configuration figure
http://h3sonline.com/forums/attachment.php?attachmentid=3948&stc=1&d=1276629381



المشكلة أنا مش فاهم إحنا هنا بنرسم علي أساس إيه ... يعني لو كان 4 او 5 هتترسم ازاي

[vahnlle]

kamal ya sa7by ...bos since we have 3 independent soln .. we find 3 ways that represents a unique way of connecting a battary .... one way : make middle on positive volt .. and rest grounded

2nd : we connect all battaries to all 3 cond and 1 ground

3rd : we connect 1 to positive and one to negative , and rest to ground ...

we cant say we coonect 2 wires to positive , cuz that will be a linear combination of soln one


:)

[amr alaa]

The golden rule here is that you want to find three independent solution . Meaning that you can not under any circumstances get one of the three configuration as a superposition of the other two. Mathematically speaking,
Field _3 != a*Field_1 + b*Field_2
for any value of a and b
!= means not equal