Hi,

I'm dealing with RF Module designs and there are some basics that I don't understand. One of them: We are using an MCU and I am trying to organize the path from the RF pins of this MCU to the antenna. We are using the reference design of the MCU, but using a different antenna, not the antenna used in the reference design. My question here is that the pi-matching circuit in the reference design will of course change according to our antenna, but I am not sure if the design of the balun circuit used in the reference design will change depending on the antenna. In summary, if a different antenna is used than the one in the reference design, does the balun circuit there need to be changed or is it possible to use it the same way?

Thanks in advance for your answers.

 

The balun circuit matches the impedance of the antenna to the output impedance of the RF source as well as matching balanced to unbalanced outputs and antennas. If you change the impedance or type of the antenna, the balun circuit must be changed to match it to the source.

 

The balun circuit matches the impedance of the antenna to the output impedance of the RF source as well as matching balanced to unbalanced outputs and antennas. If you change the impedance or type of the antenna, the balun circuit must be changed to match it to the source.

So how are chip baluns used in this case? Because they are not designed for a specific antenna, many designers can integrate it into their designs.

 

So how are chip baluns used in this case? Because they are not designed for a specific antenna, many designers can integrate it into their designs.

Chip baluns are not universal generic designs. Each has specific properties which need to be taken into consideration. Most chip baluns are designed with an unbalanced port impedence of 50 ohms and a ratio of 1:1, 1:2 or 1:4.
You either have to choose a suitable off-the-shelf balun to match your antenna to your source or design your antenna to match the balun and source.

 

I am using a pi-matching circuit to match the antenna we are using to the balun and source. Isn't that enough? Do I still need to adjust the design?

Chip baluns are not universal generic designs. Each has specific properties which need to be taken into consideration. Most chip baluns are designed with an unbalanced port impedence of 50 ohms and a ratio of 1:1, 1:2 or 1:4.
You either have to choose a suitable off-the-shelf balun to match your antenna to your source or design your antenna to match the balun and source.

 

I am using a pi-matching circuit to match the antenna we are using to the balun and source. Isn't that enough? Do I still need to adjust the design?

If you have matched the antenna to the source, the output will depend on the source power and the efficiency of the antenna.

 

If you have matched the antenna to the source, the output will depend on the source power and the efficiency of the antenna.

Got it, thanks for your answer.