Figure 8 .4: Stacking of high-resistivity Si layer on top of the LWA.
shifters) in the transverse plane as shown in Figure 8.5. The 2D array com-
poses of a shielded 1D 1 3-unit-cell CRLH T-line-based power divider feeding 4
identical 1D 13-unit-cell CRLH T-line-based LWAs. The CRLH T-line-based
power divider is identical to each of 4 CRLH T-line based LWAs in structure,
but radiation losses a re ignored due to a shielding layer on it. A THz signal
source drives the power divider from one terminal and the ﬁrst four unit-cells
are used as matching networks to have maximized input power to multiple 1D
18.104.22.168 EM Simulation
The proposed CRLH T-line-based LWA design is veriﬁed by EM simulation
in HFSS. As shown in Figure 8.6 , the maximum eﬃciency was 6.4% in 2 30 ∼
290 GHz, and it is enhanced to 40.5 ∼ 65.2% after stacking the dielectric layer
with high resistivity of Si. The maximum enhancement of 26 times is achieved.
After the enhanc ement of eﬃciency, the maximum antenna gain of 4.1 dBi is
achieved at 280GHz. As illustrated in the radiation pattern shown in Figure
8.7, a broadside radiation is observed at 280 GHz when β = 0. Note that the
zero phase propagation at 280 GHz also provides higher gain and eﬃciency
than the neg ative phase (β < 0 at 290 GHz) and positive phase (β > 0 at
250 GHz) propagation with tilted radiation direction. Note that the zero-β
frequency of 280GHz shown in Figure 8.7 is lower than the 303 GHz shown in
Figure 3.13. This is mainly because of the increase of equivalent p ermittivity
due to the stacking of a high- resistance silicon layer.