Regarding antenna tuning and PI networks

[dingari]

Hi, I'm working on a design with nRF52832 + chip antenna. I'd like to add a PI network to be able to tune the antenna before production.

I'm working with this antenna: www.johansontechnology.com/.../2450AT18B100.pdf

The antenna datasheet recommends a series capacitor, shunt inductor and a series inductor for the matching network.

This is different from the standard PI network, which is a shunt - series - shunt configuration.

I'm leaning towards copying the design from the antenna datasheet (I'll probably need different values though), but am not shure if that might not fit my case. Would I be better off with a standard PI network?

[FormerMember]

The matching network in the antenna datasheet is called a T-network.

A T-network and pi-network can/will do the same job; match an antenna to 50 Ohm from anywhere in the Smith chart.

Which matching network should I choose?

• The difference between T- and pi-network: With a T-network the minimum number of used components is two, and in most cases three. For a pi-network, the minimum number of components is one, a likely scenario is two components, and in a few cases, three components are needed.
• Habit: If you are used to do tuning with one type of matching network, T- or pi-network, it will in most cases be faster to do tuning with the matching network type you are used to.

[zachtos]

I am doing same project using NRF52832 and chip antenna 2450AT18B100E.

My question is, I am unsure what values we should use, and I read that Nordic will help tune my antenna if I send the PCB to Norway? 

[Lakshminarayana K N]

You need to measure the impedance using VNA(Vector Network Analyser) and then based on the measurement values you need to chose the values.

A detailed study on Smith chart would help you choosing values.

Hope this could help: www.youtube.com/watch

After tuning you can check the Output Power using Spectrum analyser.

Thanks.

[zachtos]

I do not have those tools in lab.  So I was looking to see if Nordic has a way to ship for tuning, as they posted about it here somewhere.