Impedance matching : Interesting Thomas Lee problem

[willdoit]

impedance matching problems

He is very ambiguous in what he is asking about in 2nd ed problem 3.1.
Any directions will be appreciated. I have read the chapter very properly and understand the L-match etc but cannot figure out what is he talking about.
It seems like some important point the seniors must know.

Consider two approaches to matching a purely resistive 75 Ohm load to a source whose impedance at some frequency happens to be 50 + j 10.
A) Downwardly mobile engineer A, after reading about the maximum power transfer theorem, dutifully adds a 25 Ohm resistor and a capacitor of - j I0 in series with the source,
B) engineer B offers a similar solution but replaces the 25 Ohm resistor with an appropriateIy designed L-match.

Quantitatively compare the two approaches by computing expIicitly the ratio of
powers delivered to the 75 Ohm load by these two solutions, assuming equal Thevenin source voltages. Qualitatively explain the reason for the difference, and why engineer A can look forward to a long career at SubOptimal Products, Tnc.

 

[flatulent]

There are two networks between the source and load. The one with resistors will have high loss and the LC one low loss.

1. design the LC network.

2. set the source to 1 V and calculate the load power in both cases.

 

[willdoit]

Thanks but Dr. Lee says "engineer A can look forward to a long career" that is he is saying that the design using the resistor is better!!!!!!!

Also, I am not able to understand where is he willing to put the match. If it was L-match from 75 Ohm to 50 Ohm, I can understand but he is talking about 25Ohm.

 

[Encrypted]

Read it again, he's saying that solution A is not optimal.

"...engineer A can look forward to a long career at SubOptimal Products, Inc."

The match is between a 50+j10 ohm source and 75 ohm load. The 25ohm resistor used by engineer A has been removed. Engineer B uses the -j10 capacitor to cancel the +j10 and then an L network to complete the match.

 

[willdoit]

I also hope what you are concluding from his ambiguous remark is correct. Thanks.