Homepage - RF Cafe
Webmaster: Kirt Blattenberger | KB3UON | Sitemap | ©1996-2014
Menu below is just a small sample of what is here!
 
Custom Search
More than 10,000 searchable pages indexed.
•−•  ••−•    −•−•  •−  ••−•  •
RF Cafe Morse Code >Hear It<

Measure tuner loss in matching circuit - RF Cafe Forums

Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views. It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if you would like to post something on RF Cafe's Facebook page, please do.

Below are all of the forum threads, including all the responses to the original posts.


sos
Post subject: Measure tuner loss in matching circuit Posted: Thu Aug 04, 2005 7:55 pm
Can anyone explain to me the most accurate way to measure the tuner insertion loss in a matching network...Thank you


Top

Guest
Post subject: Posted: Fri Aug 05, 2005 8:51 am
Are you really looking for the most accurate way?

What are you calling a tuner? A parallel open circuit or short circuit stub on a PCB?

If this is the case I suggest you cascade the network with an impedance inverting length of transmission line in between and re-resonate the matching network to 50 ohms. When you match back to 50 ohms (only one frequency unfortunately), you get a system which have the insertion loss of the 2 times the tuner, plus a quater wave line that you can easily remove from the loss also.

This way a VNA measurement will give you the results.


Top

sos
Post subject: Posted: Fri Aug 05, 2005 11:05 am
There is NO accurate way to measure the insertion loss of the slug tuner after it tuned to optimize for best performance in a matching network. However, if you can explain a better measurement method to measure the slug tuner loss after it tuned to a certain impedance. A suggestion is to put a 50 ohm line in series with the tuner which measure the total loss of resistive loss + load mismatch loss. This idea still questionable because the tuner is not 50 ohm. Then, this measurement is NOT valid. May I repeat the case: I have to measure the insertion loss of a slug tuner after it been tuned to optimize for best performance in a matching network.

Thank you


Top

Drew T.
Post subject: Posted: Fri Aug 05, 2005 11:17 am
If your frequency is within the BW of an available oscilloscope, you can always probe the voltage at the input and at the out of the tuner and get a ratio. Insert a Tee at both ends of the tuner to probe. Of course, there will be some abiguity due to the Tees, but you can probably then add back in the measured IL of the Tees. How exact are you looking to be?


Top

sos
Post subject: Posted: Fri Aug 05, 2005 4:01 pm
The slug tuner is connected to the output loadline, so the impedance transformation at that connection is NOT 50 ohm. Therefore, we cannot measure the exact insertion loss with the VNA, because the VNA is the 50 ohms system. How accurate? I guessed that there is NONE, but better estimate measure technique is what I am trying to understand...What do you think about use another tuner to tune the conjugate impedance of the first tuner? Now, we got 50 ohm system...The question is How do we determine the real loss of the first tuner? Any thought?


Top

Guest
Post subject: Posted: Fri Aug 05, 2005 5:14 pm
It is 50% of the total loss.


Top

sos
Post subject: Posted: Sat Aug 06, 2005 3:32 am
cool...that is what I thought...May take the total divide by 2 then...thanks guys



Posted  11/12/2012
A Disruptive Web Presence

Custom Search
Over 10,000 pages indexed! (none duped or pirated)

Read About RF Cafe
Webmaster: Kirt Blattenberger
    KB3UON

RF Cafe Software

RF Cascade Workbook
RF Cascade Workbook is a very extensive system cascaded component Excel workbook that includes the standard Gain, NF, IP2, IP3, Psat calculations, input & output VSWR, noise BW, min/max tolerance, DC power cauculations, graphing of all RF parameters, and has a graphical block diagram tool. An extensive User's Guide is also included. - Only $35.
RF system analysis including
frequency conversion & filters

RF & EE Symbols Word
RF Stencils for Visio

Product & Service Directory
Personally Selected Manufacturers
RF Cafe T-Shirts & Mugs

RF Cafe Software

Calculator Workbook
RF Workbench
Smith Chart™ for Visio
Smith Chart™ for Excel
Your RF Cafe Progenitor & Webmaster
Click here to read about RF CafeKirt Blattenberger... single-handedly redefining what an
                                 engineering website should be.

View the YouTube RF Cafe Intro Video Carpe Diem! (Seize the Day!)

5CCG (5th MOB): My USAF radar shop

Airplanes and Rockets: My personal hobby website

Equine Kingdom: My daughter Sally's horse riding website