Table 2.1 summarizes the proposed Cassegrain receiver suite. Figure 2.2 shows the arrangement of the feeds around the secondary focus.
| Band | Range | Bandwidth | Polarization | Status | |
| (GHz) | Ratio | ||||
| L | 1.10-2.00 | 1.82 | Circular/Linear? | New Feed | |
| S | 2.00-4.00 | 2.0 | Circular/Linear? | New | |
| C | 4.00-8.00 | 2.0 | Circular/Linear? | Upgrade | |
| X | 8.00-12.0 | 1.5 | Circular | New Feed | |
| Ku | 12.00-18.00 | 1.50 | Circular | Upgrade | |
| K | 18.00-26.50 | 1.47 | Circular | Upgrade | |
| Ka | 26.50-40.00 | 1.51 | Circular | New | |
| Q | 40.00-50.00 | 1.25 | Circular | Complete |
Figure 2.2: A possible arrangement of eight
Cassegrain feeds around the secondary focus circle.
Two new receiver systems will be added at the Cassegrain focus: 2.4 GHz and 33 GHz. A stand-alone 2.4 GHz feed will fit on the feed ring and will give higher performance than, an 1.4 GHz/2.4 GHz dual-band feed such as that on the Australia Telescope Compact Array. The 2.4 GHz band offers the highest sensitivity for studies of optically thin synchrotron-emitting objects, as shown in Figure 2.1 by the proximity of the sensitivity curve to the dashed synchrotron-spectrum line. It will also let the VLA participate in VLBA observations, and in bistatic planetary radar observations with Arecibo Observatory and Goldstone, at this wavelength.
The 33-GHz band is potentially the most sensitive band for detecting and imaging thermal objects with the VLA (as shown in Figure 2.1 by the proximity of the sensitivity curve to the dotted thermal-spectrum line). It is a band rich in molecular transitions, and is of interest to studies of optically thick (very compact) synchrotron sources.
It is advantageous to use circular polarization in the signal transmission, as amplitude and phase variations between the two oppositely polarized channels then have less effect on the measurement of linear polarization. The five high frequency bands, each covering a bandwidth ratio of 1.5:1, will use polarizers of a design now being tested with the new K-Band VLA receivers. These devices are large, and therefore unsuitable for the three lowest bands, where we will use polarizers employing a 3 dB hybrid design that are expected to provide sufficiently pure conversion from linear to circular polarization.