The advantages of DiBis over BIFODELs for implementing the RS portion of the system include lower cost ([approximately] 2 orders of magnitude less per delay line, mostly due to reduced switch cost), the potential for RS delay implementation in integrated form using GaAs MMIC and/or wafer-scale techniques and smaller size.
For this PAA, the delay ranges, as determined by the LSB and MSB delay bits of the delay lines, were 8.2 to 260.7 ps, 16.3 to 521.4 ps, and 24.4 to 782.1 ps for the three DiBis, and 32.6 to 1042.7 ps, 65.2 to 2085.5 ps, and 97.8 to 3128.2 ps for the three BIFODELs. To implement negative scan angles, the antenna was time-biased so it is steered at -45 [degrees] when the TTD network provides zero delay.
Two generations of fiber-optic delay lines (BIFODELs) have been developed.
The BIFODELs are packaged on a 10 x 14 [in.sup.2] plexiglass board that also houses the DMUX.
Overall, the time delay performance of the BIFODELs is found to be similar to that of the DiBis, which is an interesting result in view of the fact that completely different technologies are involved.