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# Insertion loss? - RF Cafe Forums

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

 Post subject: Insertion loss? Posted: Tue Feb 06, 2007 10:18 pm
 Captain

Joined: Sat Apr 23, 2005 2:09 pm
Posts: 19
Location: Tampa, FL
Hi

Is cable loss the same as insertion loss?

If I were to test a cable under a calibrated network analyzer setup, would I be able to figure out the cable loss using the S-params?

I'm thinking that insertion loss is just S12 - S11, but I don't know much anyway.

Thanks!

 Post subject: Posted: Wed Feb 07, 2007 3:47 am
 General

Joined: Tue Mar 15, 2005 11:43 pm
Posts: 67
Location: Singapore
Hi :

The insertion loss is basically the loss as the ratio of Pout and Pin. Or, well known as transmission coefficient.
So insertion loss = |S21| and since the cable is passive device, so |S12|=|S21| . If the cable is low-loss, the |S21|=|S12| must be somehow equal or close to zero dB.

In addition, S11 refers to reflection coefficient, which means how much the input power that is reflected. Again as cable is passive device, so |S11| = |S22|. at low-loss cable, the |S11| = |S22| must show low values, preferable <-20dB.

I hope it helps.

Regards,
Jean

 Post subject: Posted: Sat Feb 10, 2007 4:54 am
 Captain

Joined: Sat Apr 23, 2005 2:09 pm
Posts: 19
Location: Tampa, FL
Thanks, Jean!

Posted  11/12/2012
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