Copyright: 1996 - 2024
BSEE - KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed
formulas and reference material while performing my work as an RF system and circuit
design engineer. The World Wide Web (Internet) was largely an unknown entity at
the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps
while tying up your telephone line, and a nice lady's voice announced "You've Got
Mail" when a new message arrived...
All trademarks, copyrights, patents, and other rights of ownership to images
and text used on the RF Cafe website are hereby acknowledged.
My Hobby Website:
Questions about some equations in Rohde's book - RF Cafe Forums
RF Cafe Forums closed its virtual doors in 2012 mainly due to other social media
platforms dominating public commenting venues. RF Cafe Forums began sometime around
August of 2003 and was quite well-attended for many years. By 2010, Facebook and
Twitter were overwhelmingly dominating online personal interaction, and RF Cafe
Forums activity dropped off precipitously. If the folks at
phpBB would release a version with integrated
sign-in from the major social media platforms, I would resurrect the RF Cafe Forums,
but until then it is probably not worth the effort. Regardless, there are still
lots of great posts in the archive that ware worth looking at.
Below are the old forum threads, including responses to the original posts.
|-- Amateur Radio
Gripes & Humor
-- CAE, CAD, &
Test & Measurement
Post subject: Questions about some equations in Rohde's
book Posted: Thu Oct 30, 2008 10:41 am
Mon Apr 10, 2006 12:43 pm
some questions about an equation in Rohde's book - Communications Receivers
(2nd Edition). I am hoping someone can help me unlock my brain.
My first question deals with figures 3.2a and 3.2b (Page 96).
Signal generator (Eg) -> source impedance
(Zg) -> voltage noise source 1 (En1) -> noise free network ->
voltage noise source 2 (En2) -> load impedance (Zl)
Signal generator (Eg) -> source impedance (Zg) -> voltage
noise source (En)-> current noise source (In) -> noise free network
-> load impedance (Zl)
The noise free network is described
by Z-parameters (Z11, Z12, and Z22)
On page 101 the authors
state that the output voltage source (En2) can be replaced by an input
voltage source that will produce the same output. The source they come
up with is -(E11 + Zg)(En2/Z21). They continue by saying that the open
circuit voltage ZgEn2)/Z21)] is just that from an input current source
How do they get the source -(E11 + Zg)(En2/Z21)?
My brain is stuck on this problem and to make matters really
annoying I have solved this problem in the past.
Thank you for
your time and help.