Antenna 207
Figure 8.10: HFSS simulation results of the propose d SIW antenna
radiation pattern at 270 GHz.
8.4.2.2 EM Simulation
The proposed antenna str uc ture is verified by a full wave simulation in Ansoft
HFSS. Figure 8.9 shows the simulated radiation pattern at 270 GHz. It has
a broadside radiation pattern with 6.2-dB directivity and a 21.4% radiation
efficiency at 270 GHz. As a result, a -0.5-dB antenna gain is obtained as il-
lustrated in the simulated 3D radia tion pattern in Figure 8.10 . Figure 8.11
shows the simulated E-field distribution of SIW cavity at 270 GHz, where a
circularly polarized field distribution is observed with two modes (f
120
and
f
210
) excited with a phase difference of 90
◦
. The simulated 3dB-axial-ratio
frequency range is 265.6–274.5GHz as observed from Figure 8.12. Figure 8.12
also shows the S11 of the proposed antenna. As a result of the difference be-
tween W1 and L1, f
120
is slightly different from f
210
. There by four resona nc es
are generated including in f
120
, f
210
, f
L1
and f
W 1
, resulting in a very wide
-6dB S11 ba ndwidth of 32.1GHz centered at 268GHz.
208 Design of CMOS Millimeter-Wave and Terahertz Integrated Circuits
Figure 8.11: HFSS simulation results of polarized vector ele ctric field
in the slots of SIW cavity at 270 GHz.
Figure 8 .12: HFSS simulation results of input S11 and antenna axial
ratio on broadside radiation direction.
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