A Wide-Band Millimeter Wave RWG to Air-Filled SIW Transition

In this paper, a simple linearly tapered transition from a rectangular waveguide (RWG) to an air-filled SIW (AFSIW) is designed by analytically formulating its length, which optimizes the impedance matching and insertion loss over the wide millimeter wave frequency range. Several of these transitions are used to realize back-to-back and transmission systems supporting different waveguides. Their performances in terms of S11 and S21 are simulated and found to be <-10 dB and >-0.21 dB across the frequency bands of operation, respectively. The prototype of the transition in transmission system configuration supporting the WR-15 waveguide is developed, and its measured values from 50 to 75 GHz correlate very well with the simulated results. When the measured S21 and BW of the developed prototype are compared to similar works reported in the literature, the benefits of the proposed transition are confirmed for developing low-cost future generations of wireless technology systems.