In reply to Rachelle McWright:
Good to hear that the 5402 is working great! I can think of a couple of answers, but without accessing any silo drawings, I can just give you some very rough guidelines:
1. It can be a simple matter of adjusting the noise threshold for the lower part of the vessel - typically, the signal become weaker with the distance.
2. If the radar is installed close to the silo wall, I would suggest you to try to move it to a position closer to the silo center (best practice is a position at 2/3 tank radius)
3. You can use an 8" parabolic antenna instead. It has a narrower beam, focusing the energy. It also come with a swivel connection, so that it is possible to aim the antenna a bit closer to the center of the pile.
I would higly recommend you to contact your local Emerson representative and, if possible, supply silo drawings and plots from the device in order for us to investigate the matter further!