avins_123
Member level 2
Hello,
Can anybody please provide answers for these questions ?
These are the questions for which I have not got satisfactory answers, For some questions, I have got answers and I have written them, Please let me know whether they are correct.
The questions are
My project is "Design of a stripline to Microstrip transition"
How to calculate
1) Power( I/P, O/P and P-P power) of the transition( They say it is calculated from insertion loss i.e, for -0.5dB, it is 1.23watts, Is this right).
Answer) If you inject 30dBm (1W), the reflected signal will be 4dBm (2.5mW)
and the transmitted signal 29.5dBm (891mW). Since 891+2.5 < 1000, some power
must be lost somewhere else.
2) Bandwidth of the transition( These are transmission lines and not antennas), I found that BW definition is fh-fl / fc, i.e, fh=3GHz, fl = 4GHz, fc = 3.5GHz, so that means BW is 28.57%, Is this right ?
Answer) I found this to be the right one.
3) Why is RT Duroid 5880 the best choice for the substrate ?
Answer) Because the loss tangent is the lowest as compared to FR4 and other materials.
4) Hos does er affect the transition, return and insertion loss ?
Answer) I need this answer.
5) Why is return loss always negative and more and insertion loss positiive and less ?
Answer) Return loss is the reflected power, comes backward to source, hence negative and insertion loss is the loss which results because of some termination or discontinuity, hence positive.
6) What does -26dB Return loss and 05dB Insertion loss actually mean ?
Answer) Reflected power is 26dB less than input power, and transmitted power is 0.5dB less than input power.
7) How is Bandwidth expressed as percentage ?
8) Could you please provide me the equivalent electrical circuits for
a) Stripline
b) Microstrip line
c) Coaxial line
d) Via
I have tried a lot of books, this gives only transmission line equivalent circuit.
9) And coming to insertion loss, in some books, it is given that IL = 10 log( pt/pr), So, here insertion loss -0.5dB, That means pt/pr will be roughly equal to 1.22watts, Can power be measured in this way also ?
10) I searched for the length formula in the pdf you have sent, But I could not locate the formula. Plz, plz provide me the formulas to calculate the
1) Electrical length of the Stripline and Microstripline
2) Physical length of the Stripline and Microstripline
3) Effective length of Stripline and Microstripline
11) Finally, I have designed the transition using HFSS, Before the simulation, I found out width, length, impedance and other such values by using formulae from pozar textbook, When I designed the HFSS model using these values, I got a poor return loss and a high insertion loss, Later, I
did a lot of optimization( changing the values) and then I got the correct return and insertion loss( objective was to get values above ( -15dB and -1dB), Why does this happen ? Does that mean that formulae given in pozar for stripline and microstirp line are incorrect, Does HFSS use more accurate
formulae ?
Please provide me solutions for these questions, I will be ever grateful to
you.
Regards,
Avi
Can anybody please provide answers for these questions ?
These are the questions for which I have not got satisfactory answers, For some questions, I have got answers and I have written them, Please let me know whether they are correct.
The questions are
My project is "Design of a stripline to Microstrip transition"
How to calculate
1) Power( I/P, O/P and P-P power) of the transition( They say it is calculated from insertion loss i.e, for -0.5dB, it is 1.23watts, Is this right).
Answer) If you inject 30dBm (1W), the reflected signal will be 4dBm (2.5mW)
and the transmitted signal 29.5dBm (891mW). Since 891+2.5 < 1000, some power
must be lost somewhere else.
2) Bandwidth of the transition( These are transmission lines and not antennas), I found that BW definition is fh-fl / fc, i.e, fh=3GHz, fl = 4GHz, fc = 3.5GHz, so that means BW is 28.57%, Is this right ?
Answer) I found this to be the right one.
3) Why is RT Duroid 5880 the best choice for the substrate ?
Answer) Because the loss tangent is the lowest as compared to FR4 and other materials.
4) Hos does er affect the transition, return and insertion loss ?
Answer) I need this answer.
5) Why is return loss always negative and more and insertion loss positiive and less ?
Answer) Return loss is the reflected power, comes backward to source, hence negative and insertion loss is the loss which results because of some termination or discontinuity, hence positive.
6) What does -26dB Return loss and 05dB Insertion loss actually mean ?
Answer) Reflected power is 26dB less than input power, and transmitted power is 0.5dB less than input power.
7) How is Bandwidth expressed as percentage ?
8) Could you please provide me the equivalent electrical circuits for
a) Stripline
b) Microstrip line
c) Coaxial line
d) Via
I have tried a lot of books, this gives only transmission line equivalent circuit.
9) And coming to insertion loss, in some books, it is given that IL = 10 log( pt/pr), So, here insertion loss -0.5dB, That means pt/pr will be roughly equal to 1.22watts, Can power be measured in this way also ?
10) I searched for the length formula in the pdf you have sent, But I could not locate the formula. Plz, plz provide me the formulas to calculate the
1) Electrical length of the Stripline and Microstripline
2) Physical length of the Stripline and Microstripline
3) Effective length of Stripline and Microstripline
11) Finally, I have designed the transition using HFSS, Before the simulation, I found out width, length, impedance and other such values by using formulae from pozar textbook, When I designed the HFSS model using these values, I got a poor return loss and a high insertion loss, Later, I
did a lot of optimization( changing the values) and then I got the correct return and insertion loss( objective was to get values above ( -15dB and -1dB), Why does this happen ? Does that mean that formulae given in pozar for stripline and microstirp line are incorrect, Does HFSS use more accurate
formulae ?
Please provide me solutions for these questions, I will be ever grateful to
you.
Regards,
Avi
