Wideband SIW-based Low-cost Multi-layer Slot Antenna Array for E-Band Applications

This paper proposes a substrate integrated waveguide (SIW) slot antenna array for wideband gigabyte mobile radio application in E-band. The wideband unit cell design is based on simultaneous feeding of 4-element radiation slots with a higher order cavity mode directly excited by a simple slot aperture fed by a microstrip fork-like tuning stub. Employing the higher order mode along with the slot aperture facilitate low loss, simple feeding network and lower sensitivity to fabrication errors. To cancel the beam tilt versus frequency, the higher order mode unit cell is used in a 2 × 2 array along with a differential feeding structure. The array was designed and taped out using a new high-resolution multi-layer PCB technology and characterized by using the constructed millimeter wave measurement setup at KU Leuven /IMEC. This technology provides the possibility to stack micro-vias in PCB boards and reduce fabrication cost compared to other multi-layer technologies in mm-wave bands. The proposed array in 2 × 2 array configuration has a measured bandwidth of 11.4 GHz (16%), a total efficiency of 69%, a realized gain of 12 dBi at 72 GHz and a 3-dB gain bandwidth that covers the entire impedance bandwidth. In comparison to existing E-band SIW slot arrays (compensating for array sizes), the proposed design achieves similar or better performance in bandwidth but with lower cost, lower sensitivity to fabrication tolerances and higher total efficiency.