12 . 3. 3 CAPITAL COST AND SIZING ANALYSES Three sets of calculations have been prepared in Appendix J giving sources of information and the rationale for assumptions. These should serve as a nroad map" to do similar calculations making similar assumptions as the needs or considerations in the program change. The transmitting antenna has been sized at a value of 64. 7x10 m (910. m diameter) as the near optimum value with respect to minimum cost for the final operational systems, assuming about 100 total. The initially deployed operational systems are assumed to operate at low overall efficiency of n = 0. 536 and to tend toward the high costs noted by (H). The final operational systems are assumed to operate at high overall efficiency of n = 0. 6345 and to tend toward the low costs noted by (L). Figure 12-33 summarizes the major results of the analyses. 12 .4 CONCLUSIONS AND RECOMMENDATIONS a. Capital specific cost decreases as ground power output increases. b. At higher power levels, cost is lowest near 2 GHz. c. Frequency of 2.45 GHz in the industrial band is the recommended choice. d. System configurations having ground bus power levels above 5 GW 2 exceed 20 mW/cm peak ground power density which is beginning to affect the ionosphere and so 5 GW is currently recommended as the maximum for planning purposes. Further in-depth analysis and testing is required to understand these effects more thoroughly and perhaps relax the constraint. e. Overall MPTS efficiency is expected to be about 54%-56% initially with improvement potential to about 63%-67% for amplitron conf igurations; klystron configurations would be 49%-52% to 56%-59ao. f. Amplitrons result in lower cost systems than do klystrons. g. Aluminum results in potentially lower cost but more complex systems than do graphite composites.
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