Feed Placement

Recall that from the constraints outlined in Sec 19.5 it had been decided that the feed turret should be cubical in shape. Fig 19.7 shows the placement of feeds on the turret. The phase-centers of all the feeds are coincident with the paraboloid focus. The space between the turret and the feed is utilized for mounting the front-end electronics. There are six bands altogether, $1000-1450$ MHz^19.2, $610$ MHz, $327$ MHz, $233$ MHz, $150$ MHz and $50$ MHz. The 50 MHz feed^19.3 is affixed onto the feed support legs and not onto the turret. As such it is in focus at all times. The $610$ MHz and $233$ MHz feeds are mounted on the same turret face.

Figure 19.7: Schematic diagram showing the arrangement of the different feeds on the feed turret.

Each type of feed - its design and performance are briefly outlined in the following sections. More information can be found in [8].

Footnotes

... MHz^19.2

Note that some of the antennas have feeds that extend to 1750 MHz.

... feed^19.3

Which is not yet operational