50 ohm characteristic impedance.

[1a2s3d4f]

Hi everyone,

I don't understand the reason that most RF wireless transmission systems optimized for power transfer are 50-Ω characteristic impedance systems. Can someone explain this for me.

Thanks

 

[mowgli]

The choose of 50 Ohm originates from the fact that this value was the characteristic impedance of the "optimum (*) coax cable" (with air dielectric) used for early radio transmitters, therefore it was adopted as reference value.

(*)
Optimum in the sense that this value represents a good compromise between max power handling and linear loss requirements.

Regards

Mowgli

 

[Kral]

1a2s3d4f,
It turns out that the optimum value is 51 Ohms. For an excellent article on this subject, go to
.
. **broken link removed**
Regards,
Kral

 

[pngzhi]

there are different matchings at 50 ohm or 75 ohm. This is because the reflection is minimum when there is matching in impedences.