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λ/2 dipole is placed
above a large platform representing a payload fairing.
The fairing length is 8.66 meters, while the largest
cross-section diameter is 2.9 meters. Simulation
frequency is 2 GHz, which means that fairing length
is about 58 λ.
With one symmetry plane
applied, the model requires 44614 unknowns (rigorous
MoM). Thus, 15.9 GB of memory would be needed for
simulation.
By applying “smart
reduction” and one shadow region, memory
requirements are significantly diminished. Four
different sizes of the shadow region were tried (figure
to the right).
All the results show very
good agreement. With as few as 5000 unknowns,
discrepancies occur at side-lobes with levels lower than
25 dB relative to the gain. At that point, the model
employs 9 times less unknowns than the one with
default formulation, occupying about 80 times less
memory.
All four simulations were
done on a Pentium 4 computer with a 3.2 GHz CPU,
employing the iterative solver. In case of 4983
unknowns, iterative solver needed 85 iterations and 201
seconds to provide the acceptably accurate radiation
pattern.
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Payload fairing model
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Radiation pattern – plane
perpendicular to the dipole
antenna axis |
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