Also you asked what affects the issue the most all of the items you asked about. You need to rent an RF network analyzer to check the VSWR of the circuit and also it will help you determine what you could do to tune the circuit. We used conductive copper tape to tune the circuits. You want to insure your design can stand variations in PC board etching and copper thickness.
A microstrip line has a signal trace on top of a substrate with a ground plane beneath the substrate.
shows a snapshot of the cross-section of the microstrip line. The following
major factors affect the characteristic impedance
of a microstrip line:
Substrate height (H)
Dielectric constant of the substrate (εr)
Width of the trace (W)
Thickness of the RF trace (T)
remember this is a very high Frequency signal and needs correct design methods to work correctly.
Thanks for your comments. They were all useful for me