In the past two decades number of studies have been reported on the use of thermoplastics as a substrate for 3D printed patch antennas. However, no work has been reported on the thermoplastic-thermosetting composite-based substrate for 3D printed patch antennas and their mechanical, morphological, rheological, and radiofrequency (RF) characterization for sensing applications. In this study low-density polyethylene (LDPE) and LDPE-5% bakelite (BAK) composite-based patch antenna (resonating frequency 2.45 GHz) were printed (for secondary recycling) on fused deposition modeling (FDM) setup. The RF characteristics were measured using a vector network analyzer (VNA). Ring resonator test was used for measuring the dielectric properties of substrates (which suggests that the dielectric constant (
) and loss tangent (
) for LDPE was 2.282 and 0.0045, whereas for LDPE-5%BAK the calculated
and
was 2.0663, 0.0051 respectively). This study highlights that for the LDPE-5%BAK composite there was a marginal increase in the size of the patch antenna; but this resulted in improved transmittance, gain, and return loss for typical sensor applications. As regards to printability of substrate, 5% BAK resulted in a melt flow index (MFI) of 9.96 g/10 min in contrast to 12.208 g/10 min for a neat LDPE sample. The selected LDPE-5%BAK composite resulted in peak strength (PS) and break strength (BS) of 16.08 MPa and 14.47 MPa (at 180 °C screw temperature, 110 rpm, and 11 kg load) while processing with a twin-screw extruder (TSE), which was observed better than the neat LDPE (PS 11.98 MPa, BS 10.79 MPa). The results were supported with porosity (%), surface roughness (Ra) analysis based upon scanning electron microscopy (SEM) and bond strength using attenuated total reflection (ATR) based Fourier transformed infrared (FTIR) analysis.
