Wideband Omnidirectional Slotted-Waveguide Antenna Array Based on Trapezoidal Slots

Figure 3

Reflection coefficient comparison: dashed-red and solid-black lines are conventional SWAAs with 1 mm and 3.5 mm waveguides thickness, respectively; the dotted-blue line is an SWAA based on trapezoidal-shaped slots with waveguide thickness equal to 3.5 mm.