Project Cyclops, A Design... - Department of Earth and Planetary ...

acorresponding reductionin tunneling and cabling cost.
However, the antenna structural cost might be adversely
affected and certainly the feed horn design would be
complicated. These considerations forced us to consider
only circular dishes for Cyclops but the problem
deserves further study.
ARRAY
RADIUS
If we assume n antennas spaced a distance s apart in a
square lattice, the radius as of the array (distance from
array center to center of outer antennas) is given by
tunnel. Let the length of each section of main tunnel be
ks. If now the cost per unit length of these side and main
tunnels is "Is and "rm, respectively, the total cost will be
C = Ls7 s + Lm7 m
C = [(n-Nm) STs+Nmks7 m]
C = s[n+(kr-l)N m] 7s (L6)
2
as _ s - (L4)
while for a hexagonal lattice with antenna spacing s the
radius
ah is given by
rr h + ,_ -- 2
ns 2
J)
"h =s ) (LS)
Pattern
l(a)
Using these expressions and taking s = 300 m to permit
clear operation to 20 ° elevation with 100-m diameter
antennas, we obtain the values _iven in Table L-2.
TABLE L-2
n
as
1"O0 1543 m 1425 m
200 2244 m 2080 m
500 3635 m 3370 m
1000 5200 m 4830 m
2000 7420 m 6890 m
In round numbers, a lO00-element array of 100-m dishes
spaced 300 m apart will be 10 km in diameter and have
an effective clear aperture diameter of 3.16 kin.
TUNNEL LENGTHS AND COSTS
The branch or side tunnels will, in general, connect
adjacent antennas and so consist of(n t /Vm) sections
of length s, where N m is _he number o f sections of main
Patlrr;,
l(b)
Figure L-I. Tunnel patterns for square latti_'e array
216