Broadband ${\rm E}$ -Plane Junction for Three-Dimensional Substrate Integrated Waveguide Circuits and Systems

E-plane out-of-phase junction is proposed for three-dimensional (3-D) substrate integrated waveguide (SIW) circuits and systems. Its fabrication is made with low-cost printed circuit board (PCB) process and Lego-style planar building blocks. The proposed structure is validated through the simulation and measurement of an experimental E-plane junction operating from 30 to 40 GHz (28% bandwidth). Over this broadband frequency range, the fabricated prototype shows excellent performances with measured return loss, insertion loss and phase imbalance of better than 16 dB, 0.46 dB, and ±3^°, respectively. An integrated wideband dual-polarized array feed is designed and demonstrated on the basis of the proposed E-plane junction. The fabricated array achieves measured isolation of larger than 26 dB and return loss of better than -10.6 dB, with gains of 14 and 14.6 dBi at 35 GHz, respectively, for the vertical and horizontal radiation patterns.