We explore the dispersion properties of quasi-twist-symmetric structures using the multimode transfer-matrix method.Unlike periodic structures, these aperiodic structures do not have a translation periodicity because they are formed by translation and rotation by an angle s2π of a given subunit cell, being s an irrational number.In this work, this structure is exemplified by a pin-loaded coaxial transmission line, and it cannot be directly analyzed using commercial software due to the lack of periodicity.The results indicate that the dispersion diagrams of this kind twist-symmetric structures lie between the dispersion diagrams of periodic structures with similar rotation angles.