Width of wire between 1.5-2.5 and it’s adjustable according to the PCB size.
Along the PCB edge, make an U shape antenna, don’t make RIGHT angles, make a U shape.
It’s suggested to leave about 1CM empty apart from the antenna. It’s adjustable according to your PCB SIZE.
About the length of antenna, it can adjust according to PCB SIZE, however, PCB antenna length isn’t calculated according to the quarter wavelength which refers to the straightening length of external wire.