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The
PAS ideology consists in use of a
parallel spectrum analysis in all frequency range. For this
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purpose
all frequency range parted to the set subranges (receivers). The
amplification part of each
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receiver
is made in the scheme of direct amplification with output frequency filters. The input
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amplifiers
are executed on low noise microwave transistors. On the input of the PAS
the special
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combined
horn for all wavelengths is used. Such combined horn has one phase center
for all
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frequencies
with precision 1-2 angular seconds. It is provided the reception of the
right and left-hand
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polarization
in a modulation mode. Now the all frequency range (from 0.9 GHz to 18 GHz)
covered
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by 7
receivers with next bands: 1) 12 - 18 GHz, 2) 8 - 12 GHz, 3) 5.5- 8 GHz, 4)
3.5 - 5.5 GHz, 5)
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2.5
3.5 GHz, 6) 1.5 - 2.5 GHz, 7) 0.9 - 1.1 GHz. Each frequency band is divided
for 6-8 channels. So,
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the
receiver complex PAS consists of 48 channels with registration both
intensity and circular
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polarization
with about 5 % frequency resolution. As follows from the Table 1 the main
positive
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parameters
of RATAN-600 for solar study are:
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- The
High Flux sensitivity <0.001 s.f.u.
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The Wide range frequency coverage 0.92 GHz - 17.2 GHz with combined input
horn.
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- The
Multy frequency instant spectral analysis with 5% frequency resolution.
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- The
High sensitivity of polarization degree
measurements <0.02 %.
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- The
High dynamic range >
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But RATAN-600 has the big
difficulty with two-dimensional
mapping and
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Sun
tracking, which we try to overcome with development of Radioheliograph
regime
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(Bogod
et al., 1998) and multi-wave multi-azimuth mapping. During 2001-2002 the
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multiple
azimuth regime is realized. Now we have about 60 multiwave scans during
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4
hours (7:00 -11:00 UT) with 4 minute cadence.
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