I am designing my first 50 ohm impedance trace on a PCB that connects to a single wire antenna. I was playing around with JLCPCB's impedance calculator and I noticed a significant reduction in the trace width with a 4 layer board when compared to a 2 layer board as you can see in the pictures below:
I know the values that make the biggest difference are trace width, trace thickness, trace type, dielectric constant, and dielectric thickness.
The only thing that changes between these 2 are the amount of layers on the board. That means trace thickness (1 OZ Outer Copper Weight) and trace type (Single Ended (Non coplanar) are the same, dielectric constant changes from 4.5 to 4.6 as seen here, and dielectric height could change because we are going from 2 to 4 layers.
Since dielectric thickness is the only one that changes, does the dielectric thickness really make that big of a difference that it could decrease the required trace width by nearly 2.5mm? Is there a way to find the dielectric thickness in a JLCPCB 4 layer and 2 layer board? Because I have not been able to find the actual dielectric thickness and JLCPCB only gives the finished board height.