I am designing a pcb which has the module ublox NEO-M8N, However I am having trouble calculating trace widths. I am planning to use an FR-4 board. I was using the following calculator to try and calculate what the thickness needs to be and got a result of approx 3mm, this seems very large! I used the following parameters:

  • Dielectric Constant (εr): 4.5
  • Dielectric Height (h): 1.6 mm
  • Frequency: 1.575 GHz
  • Zo: 50 Ω
  • Elec. Length: 90 deg (You choose it at random, when you change its value, only the Length change) This is the Result : enter image description here My circuit : enter image description here

Is it possible to make the width of the strip equal to approximately 0.5mm, and change only the Length ?


1 Answer 1


Yep, that is the right size. Transmission lines scale, meaning that if you make the height smaller, the width will be smaller. If you desire a smaller width, then make the height smaller by switching the stackup (moving to a 4 layer board) or by decreasing the size of the 2 layer board.

The other parameter you can change is the dielectric constant \$\epsilon_r\$ but it's best to go with a standard stackup. So go find the manufacturer that you want to produce the board at and get the stackup, then plug in the numbers from the stackup into the calculator. Then use those numbers for the trace width.

enter image description here Source: pcbway https://www.pcbway.com/multi-layer-laminated-structure.html

enter image description here Source: https://www.emtalk.com/mscalc.php?er=4.3&h=0.11&h_units_list=hmm&f=1.6&Zo=50&EL=0&Operation=Synthesize&Wa=8.4228037104467&W_units_list=Wmm&La=0&L_units_list=Lmm

Another thing to consider is 1/20th of a wavelength for 1.5GHZ is ~10mm so you don't really need a transmission line if you put the U.FL close to the NEO-M8N.

  • \$\begingroup\$ Thank you, I will use the second solution reduce the distance, wouldn't there be a problem with the circuit? \$\endgroup\$ Commented Dec 6, 2022 at 3:31
  • \$\begingroup\$ Not if you keep it within 1/20 of a wavelength \$\endgroup\$
    – Voltage Spike
    Commented Dec 6, 2022 at 3:47
  • \$\begingroup\$ meta.stackexchange.com/questions/126180/… \$\endgroup\$
    – Voltage Spike
    Commented Dec 6, 2022 at 3:47
  • \$\begingroup\$ I made the distance 7.102mm Between U.FL and NEO-M8N, Would it be good for GPS to work? \$\endgroup\$ Commented Dec 6, 2022 at 3:51
  • \$\begingroup\$ Yeah, it should work. \$\endgroup\$
    – Voltage Spike
    Commented Dec 6, 2022 at 3:56

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