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EVLA Frequency Bands and Tunability
The EVLA electronics and local-oscillator systems enable tuning over
wider frequencies, which is possible with the wideband feeds being
installed on retrofitted antennas (or already present at K and Q bands).
In 2007, there will be enough EVLA antennas available to enable the
first observations to make use of this wideband tuning capability,
and we also will begin equipping EVLA antennas with new receiver
systems at Ka band (
1.0 cm). For example, the new C
band tuning will enable observations of methanol at 6.7 GHz, while
the new K band tuning will enable observations of the 22.235 GHz
H
O line at redshifts
to
.
Figure 3 shows the present plan for EVLA receiver
deployment over the remainder of the EVLA Construction Project,
while Table 5 gives a prediction of the new
frequency capabilities that we expect in June 2007 and December 2007.
Figure 3:
EVLA Receiver Deployment Plan.
Above are plots of planned deployment schedule
for the EVLA receivers until the end of the EVLA Construction Project in 2012.
The eight EVLA bands are listed in separate plots, with
observing frequency increasing from upper left to lower right. The decreasing
red lines indicate old VLA receiver systems. The light blue lines indicate
transition EVLA receivers; in the case of L, C, and X bands, these receivers
have the old VLA frequency coverage rather than the more expanded EVLA frequency
coverage. The green lines indicate the numbers of final EVLA receivers, and
the dark blue lines indicate the total numbers of receivers. (Note that the dark
blue and green lines overlap completely for the new S and Ka bands.) The vertical
dashed line (in purple) indicates the beginning of 2008, after which the
prototype EVLA correlator will begin to appear. Finally, the diagonal dashed line
(in black), identical for each band, gives the total number of EVLA antennas that
will be outfitted as a function of time. Approximate frequency coverage of the final
EVLA receivers is indicated below in Table 5.
 |
Table 5:
Tuning Ranges of EVLA Bands
|
Band |
Range |
No. EVLA Antennas Available |
|
|
|
June 2007 |
December 2007 |
|
20 cm (L) |
1.2 - 2.0 GHz |
2 |
3 |
|
13 cm (S) |
2.0 - 4.0 GHz |
0 |
0 |
|
6 cm (C) |
4.0 - 8.0 GHz |
1 |
2 |
|
3 cm (X) |
8.0 - 12.0 GHz |
0 |
0 |
|
2 cm (U) |
12.0 - 18.0 GHz |
0 |
0 |
|
1.3 cm (K) |
18.0 - 26.5 GHz |
7 |
11 |
|
1 cm (Ka) |
26.5 - 40.0 GHz |
4 |
9 |
|
0.7 cm (Q) |
40.0 - 50.0 GHz |
7 |
11 |
Next: Elevation Effects
Up: PERFORMANCE OF THE VLA
Previous: Sensitivity
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Jim Ulvestad
2007-04-09