Find the strip width in mils ɛeff, to meet the specification a 50 Ω microstrip on FR-4 material having thickness of 1/16 inch. Assume ɛr = 4:6., and the length at λ/4 line operating at 2.4 GHz.
Answers
For RF signal you must draw a 50 ohm net between chip and antenna to get the best performance.This post is the result of my web research on this topic …
There are two ways to design your emitter to antenna solution:
A microstrip line : basically you have a net on the top driving the signal and a ground plane on the PCB bottom
microstrip line
A coplanar wave guide : your signal is drive by a PCB net on top with two ground plane area on its left & right. If you also have a ground plane on the bottom it’s a grounded coplanar wave guide
The way to get a 50 ohm communication way is different depending on your choice.
Common consideration
The impedance of the line is mainly depending on your PCB characteristics. The most important are:
PCB Material
The PCB material are standardized with different norms. One of the most common is FR4. It defines range for most of the parameter we need to know for the wire size calculation. The problem is range are large and the calculation will vary depends on where your PCB is in the given range.
The Thickness of dielectric = the PCB height.
This is why we found RF pcb : they are particularly thin as this is allowing to make smaller RF wires. This can be a variable parameter depending on your PCB provider sourcing and these variation may impact you radio quality.
Relative Dielectric Constant (εr)
It determines how much electrostatic energy can be stored per unit of volume when unit voltage is applied and basically how the PCB act as a capacitor (as this definition is really simplified you can learn more here)
This constant depends on the material and the frequency of the communication. For a FR4 dielectric.