The growing interest in the modulation of phase
(and amplitude) of microwave and millimeter-wave signals has been spurred by the emerging 5G/6G phased-array beam-steering applications for which liquid crystal is one of the enabling technologies. A problematic journal paper on liquid crystals-based coplanar waveguide phase shifters is scrutinized in this letter to urge readers and a wider academic community’s attention. Specifically, concerns have come up about the usefulness, effectiveness, and accuracy of the simulation-only work that Jun-Seok Ma et al published recently at J. Phys. D: Appl. Phys. 55 095106, entitled ‘liquid-crystal-based floating-electrode-free coplanar waveguide phase shifter with an additional liquid-crystal layer for 28 GHz applications’. With no devices fabricated and no experimental measurements, the simulation results and conclusions are subject to fundamental yet important errors (significant overestimations) that can mislead readers as well as researchers truly working in the field of liquid crystals-based tunable microwave and millimetre-wave devices. The lack of experimental data means that the validity and reliability of the simulation results cannot be fully assessed. A reflection on other drawbacks of the article is also elaborated in this letter.