AbstractThis letter shows that the synthesis of coplanar waveguides with finite substrate thickness can be obtained by simple numerical solution from the exact quasi‐static formulae of the characteristic impedance using bisection method The novelty of the method is that accurate synthesized values compared to those from curve fitted formulae are obtained. Moreover, sophisticated numerical techniques are not required. The method can be extended to various other forms of coplanar waveguides and coplanar strips for which curve fitted design formulae may not be available.