A Wideband SIW-Based Slot Antenna for $D$-Band Applications

In this letter, a wideband substrate integrated waveguide (SIW) based slot antenna is designed for
D
-band applications. A wideband response is attributed to the merging of closely lying six resonance frequencies. Two of them at frequencies of 114.25 GHz and 134.75 GHz signifies the excitation of TE
$_{310}$
and TE
$_{120}$
modes, respectively. The modes at 124 GHz and 144 GHz are identified as hybrid modes that are formed from the combination of TE
$_{310}$
–TE
$_{120}$
and TE
$_{120}$
–TE
$_{220}$
modes, respectively. The upper two resonances at the frequencies of 154 GHz and 160 GHz occur due to TE
$_{220}$
–TE
$_{320}$
based hybrid modes. A two-step wideband WR6-SIW transition is also designed and integrated with the antenna for measurement purpose. In the first step, the three-section Chebyshev transition is developed to match the impedance of standard WR6 with a rectangular waveguide (RWG) of the same height as that of the PCB. In the second step, the RWG is matched with SIW using a dielectric extension. The final antenna with transition is simulated and measured. A wide
$-$
10 dB impedance bandwidth for
$|S_{11}| \leq -$
10 dB of 42.86% (110–170 GHz) is obtained. The gain and radiation measurements were also performed after constructing an in-house measurement system.