question about Practical microstrip line

Hi, I want to fabricate the power divider and I want to know what is the maximum impedance( or minimum width) in microstrip line that can be fabricated? I use the Taconic TLX-8 substrate with dielectric constant 2.55, thickness 1.575 mm, and loss tangent 0.002 and the center frequency is 1GHz.

You should talk to the board house that will be making the board. Most anybody can make 8 mil lines. 6 mil may cost a little extra. 4 mil is available if you are willing to pay.

Hi, I design the power divider and in this power divider impedance of one of the microstrip lines is 182 ohm, so Is this impedance practical for fabrication? if yes, what is the appropriate substrate for the fabrication?

you can make quarterwave transformers before and after power divider to make it differ from 50 Ohms. I made power division in 75 Ohms because lines was too thick for smd pads and radial arms of wilkinson. You can try 40 ohms maybe...