Antenna Tuner for nRF9151

[BilalMalik]

In section 5 of 'nRF91 Series Antenna and RF Interface Guidelines' there are a couple of circuit diagrams relating to antenna tuners, could you please provide details of how they would function practically?

How has Nordic used them? 

And what Parts has Nordic used?

[ketiljo]

A antenna tuner is used to compensate for narrow banded antennas that can't cover all the wanted LTE bands. Typically very small designs that have a ground plane too small to to provide sufficient gain on the low bands. 

There are two types. One is just a switch that is used to select different tuning components for different frequencies. The other type is device with switchable components, usually capacitors. So you can basically set the value of the tuning cap. 

The switch type is used in the Thingy91 (https://docs.nordicsemi.com/bundle/ug_thingy91/page/UG/thingy91/hw_description/hw_antenna_tuning.html) and Thingy91x (https://docs.nordicsemi.com/bundle/ug_thingy91x/page/UG/thingy91x/hw_description/lte_dect_nr_rf_if.html)

Both are using the same principle but different interfaces. Thingy91 uses MIPI (outputs) and a standard switch while the Thingy91x uses RFFE (SPI like serial interface). 

An antenna that properly covers the bands us a much better solution. Provided at that product has a sufficiently large enough ground plane.