Effect of heterogeneity in additively manufactured dielectric structures on RF response of microstrip patch antennas

摘要

Microstrip patch antennas with a tunable radiofrequency (RF) response are a greatrncandidate for additive manufacturing (AM) process. First, three separate sets of ABSrnsamples were created at three different machine preset fill densities using an extrusionrnbased 3D printer. Once fabricated, actual solid volume fraction of each set of samplesrnwas measured using a 3D X-ray computed tomography microscope. It is observedrnthat the factory preset fill-density values are only applied to the core region and actualrnsolid volume fractions for each sample set are different from printer-preset values.rnAlso, the printed materials appeared to exhibit anisotropy such that the thicknessrndirection dielectric properties are different from the in-plane properties (planar isotropy).rnMicrostrip patch antennas created on the AM fabricated ABS were tested forrnresonant frequencies using a vector network analyzer (VNA). The measured resonantrnfrequencies combined with ANSYS-HFSS simulation were used to estimate bulkrndielectric constant of ABS and equivalent dielectric properties in planar and thicknessrndirections. It is observed that the antenna resonant frequency decreases with anrnincrease in core solid volume fraction. Also, in-plane permittivity appeared to havernminimal effect on antenna resonant frequency, while the thickness direction propertiesrnhave substantial effects.