Antenna Size; Antenna Inclination; Non-Metallic Tanks - Emerson Rosemount 5408 Reference Manual

Mechanical Installation
November 2017
Table 3-2. Free Space Requirements
Description
Service space width (A)
Service space height (B)
3.3.3

Antenna size

Choose as large antenna diameter as possible. A larger antenna diameter concentrates the radar beam
and ensures maximum antenna gain. Increased antenna gain permits greater margin for weak surface
echoes.
In addition, a larger antenna diameter results in a smaller beam angle and thereby, less interference from
any internal structures in the tank.
3.3.4

Antenna inclination

Ensure the antenna is aligned perpendicular to the product surface (see
antenna comes with a swivel connection that adjusts for angled tank roofs.
Note that if the surface echo is weak in solids applications, then a small inclination of the parabolic
antenna toward the surface slope may improve the performance.
Figure 3-4. Inclination
Cone antenna/
process seal antenna
3.3.5

Non-metallic tanks

The walls in non-metallic tanks can be invisible to the radar signal, so nearby objects outside the tank
may cause disturbing radar echoes. Wherever possible, the transmitter should be positioned so that
objects close to the tank are kept outside the signal beam.
14
Distance
20 in. (500 mm)
24 in. (600 mm)
Parabolic antenna
Max. 3°
90°
Max. 1.5°
90°
Reference Manual
00809-0100-4408, Rev BA
Figure 3-4). The parabolic
Mechanical Installation