hi , I'm going to use RO4003C substrate to design coupler 180 deg , that work from 2 to 4 GHz .I got the specification from the internet of the substrate from Rogers Corporation , how do I calculate the dimension of w/d and how to get effective dielectric constant ? to let me able to finish my design .notes plz im beginner
if u want to design coupler for 2 - 4G
i would start with 32mil substrate 1oz T (1oz if u not going to work with high power signals),
height of the pcb can and will enflunce on your design (like volker_muehlhaus told it will define your line w), but once again 32mil it good start)
Zo depend on your system usually it 50 Ohm.