Figure 8

(a) Measured and simulated maximum realized gain in the E(x–z) plane (a) and the beam-pointing angle (b) for our fabricated 2L-LWA (see Fig. 2(a)). A 5-dB radiating bandwidth of about 8.7% can be observed in the measurements and simulations for the main beam positioned at broadside (when considering \({\varepsilon }_{{{\rm{r}}}_{1}}=11.5\)). This also corresponds to the main beam being positioned at broadside (see Fig. 8(b)). It is interesting to note that the observed gain variations around the broadside radiating frequencies (between 23 GHz and 25 GHz for the full-wave simulations, for example, with \({\varepsilon }_{{{\rm{r}}}_{1}}=10.2\)) are related to the double-symmetric bump of the LW attention constant. This is consistent with the numerical results in Fig. 5(a).