Lowpass Filters with Non-uniform Dielectric Properties using 3D Synthetic Printed Substrates

To overcome very narrow line widths from high impedances of microstrip line, non-uniform dielectric substrates with different infill percentages were analyzed and designed. With current development in three-dimensional (3D) printing technology, it can create the different permittivity values using a single filament material, which is used in the various portions of a microwave device. This paper presents the fabricated planar lowpass filters using non-uniform printed substrates that combines of nontoxic material polylactic acid (PLA) to produce novel dielectric substrates using 3D printer. Dielectric constant and loss tangent of the proposed substrate can be customed with different infill densities over a frequency range of 0.01-6 GHz. Two lowpass filters with a cutoff frequency of 2.2 GHz including a stepped impedance type and a stub type are designed and implemented. Good agreement between simulation and measurement results.