A Full X-Band Fully 3-D Printed E-Plane Rectangular-Coax-to-Waveguide Transition

This paper reports on a new class of broadband fully 3-D printed E-plane rectangular-coax-to-waveguide transition. This type of transition is adopted to interconnect two E-plane rectangular waveguides, and is based on a full air-filled waveguide structure without introducing other types of transmission lines (TLs). It exhibits little dielectric loss and dispersion, and furthermore a potentially enhanced power handling capability. The transition is constructed by a section of air-filled rectangular coaxial TL cascaded in series to a broadband coax-to-waveguide probe transition. A proof-of-concept X-band back-to-back transition is designed and prototyped monolithically by incorporating stereolithography-based 3-D printing and copper electroplating techniques. The RF-measured result demonstrates a broadband and low-loss characteristic of the transition — an insertion loss of averagely 0.5 dB and a return loss of mostly better than 15 dB at the entire X band.