# S11 Measurement Results

**URL:** <https://discourse.myriadrf.org/t/s11-measurement-results/5463>\
**Category:** LimeSDR\
**Created:** [10 December 2019 21:20 UTC](https://discourse.myriadrf.org/t/s11-measurement-results/5463 "2019-12-10T21:20:39Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Crater](https://avatars.discourse-cdn.com/v4/letter/c/58f4c7/32.png) [@Crater](https://discourse.myriadrf.org/u/Crater)\
**Post date:** [10 December 2019 21:20 UTC](https://discourse.myriadrf.org/t/s11-measurement-results/5463/1 "2019-12-10T21:20:39Z")

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Dear All,  
I have made S11 measurements with a LIMESDR-USB.  
The measurements were made on:  
Rx1\_L (with Easyfix2 applied)  
TX1\_1  
in the frequency range of 10 -2000 MHz

This is the measurement taken on Rx1\_L, I was on the impression thar Easyfix2 will also improve VSWR but clearly this is not the case. S11 at 70 MHz is a whopping -0.84 dB!!! (That means a loss above 7 dB)

 ![rx_s11](https://canada1.discourse-cdn.com/flex034/uploads/myriadrf/original/2X/9/92767eb9af5fad36c9e428005e2b80756952f930.jpeg)

and here you see the measurement taken on Tx1\_1. (Note there is a 70 MHz filter attached)

 ![tx_s11](https://canada1.discourse-cdn.com/flex034/uploads/myriadrf/original/2X/f/f90aa9cccddffd330201164e4888cf64451ee9db.jpeg)

I would like to optimize the matching circuits for TX and RX under 100 MHz but the matching circuits are differential which I am not used to.  
Which SW can you recommend for fine tuning the values in the matching circuit.

Thank you in advance.

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<div class="post-metadata">

**Author:** ![gerryk](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/gerryk/32/138_2.png) [@gerryk](https://discourse.myriadrf.org/u/gerryk)\
**Post date:** [8 January 2020 11:33 UTC](https://discourse.myriadrf.org/t/s11-measurement-results/5463/2 "2020-01-08T11:33:54Z")

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If you display S11 as a Smith Chart, you can see the complex impedance at whatever frequency interests you. You then add whatever capacitance or inductance is necessary to bring it to R+j0.