LAUSR

The rod milling method of cylindrical-shaped milling medium was applied to prepare the flaky carbonyl iron powders with varying milling times (10 h, 15 h and 20 h). The sample obtained by the spherical milling medium was also used as a contrast. The samples were characterized by x-ray diffraction, scanning electron microscopy and Raman spectroscopy, respectively. The complex permittivity and permeability were measured by vector network analyzer in the frequency range of 1–18 GHz. The results revealed that cylinder-prepared samples have better impedance matching properties and good absorbing properties. The minimum reflection loss (RL) of − 15.7 dB was observed at 6.0 GHz with a thickness of 1.5 mm, and the effective absorption frequency (RL < − 10 dB) ranged from 4.5 GHz to 8.5 GHz. This method is expected to play an important role for the promising design of flaky microwave absorbers, which can be applied to fifth-generation (5G) communication.