Figure 7

(a) Input reflection coefficient, in absolute value (dB), for various relevant structures and all fed by a non-directive SWL at the structure origin; i.e. a 1L-GDS and 2L-PPW (see inset and Fig. 3) as well as the examined 1L-LWAs from⁷ (with two different configurations of the MSG, as described in the figure inset) and the 2L-LWA of this work. (b) Directivity and realized gain at broadside, (defined for θ = ϕ = 0°) for the 1L-LWA s/p = 0.179 and the 2L-LWA as a function of frequency (and normalized to the frequency value for maximum realized gain at broadside for each LWA). (c) The radiation efficiency at the broadside versus the normalized frequency for the two 1L-LWAs from (a) and the 2L-LWA of this work. These results include dielectric and conductor losses as well as any mismatching losses for the compared LWAs. Also, this reported efficiency metric has been calculated by considering far-field values for when the radiated beam is at broadside only; i.e. 100% multiplied by the realized gain divided by the directivity for the dominant E_θ polarization whilst only considering values for θ = ϕ = 0° (broadside). It should be mentioned that the results for the more conventional total radiation efficiency, which considers radiation over all 3-D space and all possible losses, are well above 70% for both the 1L- and 2-LWA designs. The relevant LW attenuation constants directly computed by the MoM and considering no loss for structures, are also reported for comparison.