Electromagnetics (ENGR 367). T-line Power, Reflection & SWR. T-line Theory: Something New or Not?!. Power, Reflection and Standing Waves in T-lines act just like Uniform Plane Waves (UPW) in unbounded and layered media!
T-line Power, Reflection & SWR
sound waves in a tube since all these waves
Given:two T-lines joined end-to-end by an adaptor. Line 1 is 30 m long and is rated at 0.1 dB/m, whereas line 2 is 45 m long and is rated at 0.15 dB/m. Due to a poor adaptor, the joint imparts another 3 dB loss.
Find: the percentage (%) of the input power that reaches the output of this combination
(where the time dependence ejt has been supressed)
where the – sign arises due to neg. z-going current wave
Given:a 50 lossless T-line terminated by a load impedance, ZL=50-j75 . Power incident from the T-line to the load is 100 mW.
Find: the power dissipated by the load
Solution: first calculate the reflection coefficient
Solution: next calculate the transmitted power in terms of incident power and
Given: two lossy lines joined end-to-end.
Line 1 is 10 m long and has a 0.20 dB/m loss. Line 2 is 15 m long and has a 0.10 dB/m loss. At the junction of these two lines = 0.30. Power input to line 1 is Pi1 = 100 mW
Find: a) the total loss of the line combination in dB.
b) the power transmitted to the output of line 2.
Solution: a) first calculate the dB loss of the joint from
then calculate the total loss of the link
b) now calculate the output power as
1) Matched termination (ZL = Z0 = 0)
2) Perfectly reflective termination ( = 1)
3) A partially reflective termination (0<<1)
(animated partial standing wave pattern)
Real Reflection Coefficient Complex
Given: = 3/5
Find: VSWR = ?