^This. The term for this field is electro-magnetic resonance. N-trig, in fact, does not support the pen being wirelessly powered via electro-magnetic resonance. Nor does the vast majority of stylus technologies in existence: Wacom AES, Synaptics, Atmel or the Apple Pencil. The digital pens/styluses/styli emit a signal of varying types to the display digitizer including a pressure level-encoded signal and the digitizer de-scrambles this information on-the-fly. The only commercially available technology that supports wirelessly powered or battery-less electro-magnetic resonance is called (brace yourselves! it's a shocker of a name) Wacom EMR. Though quite popular in the past (notably, found in the Surface Pro 1 and 2 and the Asus VivoTab Note 8), unfortunately no currently manufactured Windows tablets support Wacom EMR.
However, the upcoming Samsung Galaxy Book 10 and 12 will again feature it and each will be equipped with an updated enhanced version of Wacom EMR now with tilt detection, an all-new feature for Windows tablets. What this also means for Eve and their future tablets is an EMR digitizer can now be put into other future 3:2 aspect ratio tablets since these Samsung tablets, which are 3:2 aspect ratio, will be equipped with a 3:2 aspect ration digitizer which up until now did not exist and was not manufactured. In other words, we could have a future Eve tablet with a 3:2 aspect ratio Wacom EMR digitizer since the part is now commercially produced and should be available to other companies soon if not already now. Most professionals artists I know (see the TabletPCReview Forum) widely and vastly prefer Wacom EMR since it has a very analog, smooth, graceful feel to it with essentially zero IAF (initial activation force). In other words, you can go from nearly infinitely fine, light lines to full, solid, bold lines with Wacom EMR as if you were inking on actual paper.
However, let this be made clear: for 99% of people, the latest version of N-trig which the Eve V and the Surface Pro 4 both use is far more than adequate. In fact, it is rather excellent and it will serve note takers and beginner through intermediate artists alike perfectly well. I use it for engineering work and the occasional doodle session in Krita (which is completely free and highly recommended, by the way! I know a great many artists who prefer it to Photoshop: https://krita.org/ ) and it is more than sufficient for my needs.