So I'm looking at building a satellite receiving stations (amateur bands). I know that a station that is transmitting requires grounding of the RF components due to the high power of the transmitter, but do I need to ground my station if I only plan on receiving?
I'm hoping to learn here, so top answer will explain the rational behind the yes/no. :)
Let's first eliminate some reasons:
If you have a receiving antenna which is permanently outdoors, then you may want grounding for lightning protection. This is a substantial topic of its own which I am not qualified to describe briefly here. This is largely a separate topic from grounding for RF purposes, though some of the design principles are useful in both cases.
Some types of antennas, deliberately or accidentally, have connections to ground as part of their functional structure. Directional, rotatable antennas such as Yagi, log periodic, or dish antennas, as you would use for satellite work, do not.
There are reasons for grounding applicable here: electrical safety and RFI. Electrical safety is not specific to this application; the usual rules apply, and we'll assume that your line voltage power supplies are properly grounded and everything else (your computer, radio, antenna rotator...) is low-voltage.
That leaves RFI (radio frequency interference). We need to think about grounding and shielding. The purpose of shielding is to prevent noise from entering sensitive circuits or leaving noisy ones. The purpose of grounding is to allow noise which is flowing on some (shield/ground) conductor to preferentially flow to earth rather than into your receiving equipment.
In theory, a receiver does not need a ground at all: if the entire system is enclosed in an impermeable shield, with appropriate filtering at power, antenna, and received-signal-out ports, then grounding has no effect whatsoever.
In practice, anything you can do to reduce the noise power around by redirecting it to earth via a ground connection may be useful.
Caveat: your ground connection needs to not have the effect of conducting noise from a noisy component to a quiet one, which can happen if you wire grounds in daisy-chain fashion rather than separate wiring to a single ground bus/plane/chassis. It's also possible for the ground wiring to end up acting as an antenna for other noise; this is reduced by keeping it as short as possible.
Finally, grounding is useful not only for your receiver but also for other electronic equipment which may be producing noise that would interfere with reception. Of course, you can also “just” shut off that equipment while receiving, which is an easier option for initial troubleshooting.
As I am unable to comment on Kevin's great answer, I would add that for any device that you add grounding to, in addition to keeping it short, ensure that you have a solid earth. If you don't have solid connection you will introduce noise, not reduce it.
There is also the problem of potential(voltage) differences between multiple grounds. For example if your device has a 3 wire chassis ground though the electrical which uses single common ground in your primary-mains-service panel, and you add additional grounding to say a cold water pipe that enters the building from the other side. You now have a loop and the effectiveness of one ground over the other will generate a minor current flow between the grounds and though your device. You want to avoid floating grounds where you attach devices to each other and not to a common ground.
