A W-Band Stepped Impedance Transformer Transition from SIW to RWG for Thin Single Layer Substrates with Thick Metal Cladding

In this paper, a vertical transition from substrate integrated waveguide (SIW) to rectangular waveguide (RWG) in a single layer thin substrate PCB with thick metal cladding is proposed. A multi section stepped impedance transformer is milled into the thick metal cladding for wideband performance. The advantage of milling the stepped impedance profile directly into the thick metal cladding is that no external mechanical devices with complicated manufacturing processes are needed. This results in a lower overall manufacturing complexity when compared to competitive designs especially when multiple transitions are needed like in MIMO systems. 3D-electromagnetic simulations are used for optimization and compared to measured results to confirm the results and the functionality of the transition. Within the measured frequency range of 75 to 110 GHz, the single transitions measurement results show less than 0.6 dB insertion loss and more than 10 dB return loss.