Hi, I'm Max Landaeus and in this video I will show how to use BetaMatch to find optimized matching networks -
-to match the same antenna to three different source impedances: 50 Ohm, 20 - j20 Ohm and 300 + j300 Ohm.
For this demonstration we will use a single band Bluetooth antenna and the Touchstone data comes with BetaMatch.
The data can be loaded via the 'Help Menu' choose 'Load demo data' and select 'BT tuned high' and click OK.
Furthermore we will leave the electrical delay at 0ps and we will use the default 0402-sized Murata components.
Notice that the components are based on real measured component data with losses and everything included.
We also need to set the frequency band to the 2.5GHz band.
Go to 'Markers Menu' and select 'Bluetooth' and the band is set.
We can see that this antenna is tuned high.
We can see from the table here that we only have 35% accepted power into the antenna at 2.4GHz.
We are now ready to start our first optimization with the default source impedance of 50 Ohm.
We start an optimization for 4 components now ...
... and now it's done. It turned out to be only 3 components needed.
As you can see, the accepted power at 2.4GHz has now improved from 35% to 73%.
We save this design into Memory 1 for future reference.
We are now going to change the source impedance to 15 - j20 Ohm.
I do this from the source editor. I open it and enter the new values.
First I enter the real part: 15, and then the complex part as +20 because I am actually entering the BEST load,
our TARGET which is the conjugate of the actual source impedance.
I tick two boxes so we can see the source impedance and the conjugate in the Smith Chart.
As you can see now, the source impedance has changed to 15 - j20 Ohm.
We are now going to optimize for this new source impedance. We start the optimization...
There it is done! We have a 4 component matching network and the accepted power is now 71% at the band edges.
Also note that the S11 plot and the Smith Chart always use a 50 Ohm reference.
So this is what you design would look like when measured with a network analyzer in a 50 Ohm system.
The Accepted Power plot, on the other hand, shows the accepted power for the actual source impedance.
If we want to see what it would have been like with a 50 Ohm source we can enable that.
And that would have looked like the dotted line in the Accepted Power plot.
Let us store this design in Memory 2.
Now we will change the source impedance again. This time we will change it to 300 + j300 Ohm.
Open the source editor and change the values to 300 and -
- the imaginary part would be -300 since we enter the TARGET, the conjugate.
As you can see, the old matching network does not work at all so we will start a new optimization.
There, it is done. We can see that we have 72% and 73% accepted power at the band edges.
We have now designed different 3 matching networks for 3 different source impedances so let us compare them.
In Memory 1 we have the 50 Ohm design.
And we have the low impedance, the 15 - j20 Ohm, design in Memory 2.
We can se that the accepted power is similar for all designs but they are totally different in the Smith Chart.
Let me rearrange the windows so we can compare the results.
We will show all matching networks at the same time.
So we have 'Data' with the 300 Ohm design
We have 'Memory 1' with the 50 Ohm design
We have 'Memory 2' with the 15 Ohm design.
We can see in the table here that the accepted power is around 71 - 73% for all the designs.
That concludes this demonstration. My name is Max Landaeus and web-site and e-mail address is on the screen now.
Please feel free to contact me if you have any questions or any other feedback. Thanks for your attention.