# HELP PLEASE!!! Propagation of electromagnetic waves

Discussion in 'Homework Help' started by Alfa_ET, Mar 22, 2011.

1. ### Alfa_ET Thread Starter New Member

Feb 26, 2011
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0
Question: designing an inverter transformer for adapting a load ZL = 75ohms to a transmission line of characteristic impedance of 300ohms, and reduced losses, at a frequency of 300MHz.

Answer: length = 0.25m transformer impedance characteristic= 150ohms

Question: Determine the bandwidth of frequencies where the VSWR on the line is less than 1.5.

Answer: I need help. Analytical calculations and then confirm the Smith Chart.

grateful

2. ### t_n_k AAC Fanatic!

Mar 6, 2009
5,448
790
A quarter wave matching transformer matches the source impedance Zs to the load impedance ZL via the line impedance Zo according to the relationship

Zs=(Zo)^2/ZL

If ZL=75Ω and Zs=300Ω then the required Z0=√(Zs*ZL)=√(300*75)=150Ω

3. ### t_n_k AAC Fanatic!

Mar 6, 2009
5,448
790
Do you have access to a Smith Chart simulation program?

Feb 26, 2011
17
0

No, i don't.