how to design the length of Wilkinson power divider

i wonder if length of wilkinson divider.
each of stripline length is same?

ex) 40Mhz frequency,c=λf thus λ/4=1875 mm
wilkinson have One Input port and 2 Output port.
then each of 2 output stripline is 1875mm, right?

let see the Photo

Your calculation is valid for air only. For lines in/on PCB material, propagation is slower and the effective wavelength is smaller than the wavelength in air. If the line is completely embedded in a material, effective wavelength = free space wavelength / sqrt(eps_r)

For microstrip, the field is partially in the substrate and partially in air, depending in line width. You can then use a transmission line calculator to get the effective wavelength (or effective eps_r):
https://www.microwaves101.com/calcul...rip-calculator

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If your "?" in the pricture refers to the feed line: that is 50 Ohm, so the length doesn't matter. See https://www.microwaves101.com/encycl...ower-splitters