Additively Manufactured Wideband Transition From Microstrip to Empty SIW at <i>Ku</i>-Band

This work demonstrates the development of an additive manufacturing (AM)-based transition from a microstrip to an empty substrate-integrated waveguide (ESIW). An expanded ESIW section with a sharp dielectric taper allows for wideband impedance matching. The proposed transition is validated by simple, inexpensive, and reduced complexity using an AM technique. The top and bottom of ESIW are covered with a copper-coated polylactic acid (PLA) substrate of 0.5-mm thickness. The via holes in the ESIW are replaced by spraying copper on the internal walls. The proposed model’s veracity was further established by evaluating it against a subtractive manufacturing (SM) prototype. The measured results obtained using AM (SM) have an insertion loss of less than 2.24 dB (0.92 dB), a return loss better than 17.7 dB (18.08 dB), and 73.4% (60.8%) fractional bandwidth (FBW) over 10–21.6 (10–18.75) GHz.