In antenna tuning for EM Prox (LF) can we use X7R capacitors??? They recommend NP0 capacitor only for antenna tuning... If I use X7R what will happen???
X7R is a class II dielectric while NP0 is a class I dielectric. Class I will tend to have higher stability in terms of voltage/temperature, and generally lower losses. Also class I dielectrics tend to have less piezoelectric effects. But these classifications are quite broad and if you really want to be sure then you should look at specific devices and their datasheets.