In this paper, we present a hybrid technique for designing RAM optimally to reduce the RCS of complex targets in a wide-band frequency range. The technique combines a high-frequency method and a genetic algorithm (GA) to obtain an optimal RAM in complex targets. By the virtue of the high-frequency method, such as the physical optics (PO) method and the method of equivalent currents (MEC), the proposed technique can be applied to complex targets with relative ease. However, the high-frequency method needs a classification of shadow regions as pre-processing. A Z-buffer algorithm is employed in this process. The procedure results in designing the optimal RAM which significantly reduces the RCS of complex targets.
In order to upgrade conventional wavelength-division-multiplexing (WDM) networks, we propose to use ultradense (UD) WDM channel groups. One UD-WDM channel group replaces one WDM channel and traverses the WDM network following the same path as the original WDM channel. We show experimentally that each conventional 100-GHz-spaced WDM channel can be upgraded in this way to have the transmission capacity of 20-40 Gb/s.
A new design of a V-band hyper-non-radiative dielectric (HNRD) guide directional coupler using a multi-hole structure is described and measured results are given. The coupling structure using multi-hole between the two HNRD guides is employed to obtain wideband coupling. Measured results for the fabricated 3 and 10 dB coupler showed that return loss is greater than 16 dB, isolation is better than 26 dB, and the average coupler loss is 1.1 dB, over a percentage bandwidth of 10% at 60 GHz.
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