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An 80 GHz radar installation starts with the space between the antenna and the product, not with the transmitter settings. The mounting connection may fit while the nozzle clips the useful signal path, an agitator crosses the beam or the highest liquid surface enters the near measurement limit. Review those dimensions before ordering the instrument or fabricating the nozzle.
Put the antenna and vessel on the same drawing
A tank elevation alone cannot show whether the beam intersects a nearby inlet. Use a section and a plan view. Mark the instrument reference, the nozzle bore and length, the low and high operating surfaces, and the positions of pipes, coils, ladders and moving equipment. Show the inlet stream where it reaches the liquid, rather than marking only the roof connection.
Record dimensions from the proposed finished assembly. A spacer added after selection changes the antenna position; an internal lining can reduce the clear bore. If the fabrication drawing and the instrument drawing use different reference planes, resolve that difference before either drawing is approved.
The METRAVON MV-RD14G liquid configuration has a 44 mm PTFE antenna and a stated 6-degree beam angle. The MV-RD15G liquid configuration uses a 76 mm PTFE antenna with a stated 3-degree angle. These figures describe different assemblies; they are not interchangeable nozzle dimensions.
80 GHz radar installation: use beam width as a screening calculation
For a stated full beam angle, a simple geometric estimate of beam diameter at distance D is 2 x D x tan(angle / 2). At an illustrative distance of 10 m, this gives approximately 1.05 m for 6 degrees and 0.52 m for 3 degrees. The calculation helps compare the proposed path with internal structures. It does not establish a minimum nozzle bore or prove that a particular installation will work.
A stated beam angle is a nominal description, not an echo-free boundary: a nearby reflector outside the calculated cone can still affect the reading. Nor does the cone calculation describe all effects close to the antenna. Have a long or restricted nozzle assessed against the selected antenna's installation drawing instead of extending a simple triangle back to its face.
| Drawing feature | What the review must resolve |
|---|---|
| Nozzle interior | Clear bore, length, weld projections, lining and steps in any adapter. The nominal flange designation alone does not describe the opening. |
| High surface | Distance from the documented reference to the highest required surface, including the process allowance for movement or foam. |
| Moving parts | The swept position of an agitator or distributor, not just the position shown on a stopped-equipment photograph. |
| Service access | Room to reach the connections, inspect the antenna and remove the assembly using the site's approved access method. |
Leave usable space above the highest required level
A catalogue maximum range addresses the far end of the measurement. The installation also has to satisfy the model-specific near limit. Identify whether the relevant high surface is the normal operating level, the top of a foam layer or an abnormal rise that operators need to see. Do not set the full-scale point at the antenna face simply to obtain a convenient round span.
Keep the instrument's usable range separate from the plant's alarm design. Damping, communication and the receiving system can delay an indication. The responsible engineer must determine the operating margin and any independent protective function; an antenna clearance check is not an overfill protection assessment.
Check what will be exposed to the process
Identify the antenna, seal and connection materials individually. A PTFE antenna does not make every component chemically compatible. Include cleaning chemicals and wash conditions as well as the stored liquid. Keep the electronics environment separate from the temperature at the process connection, especially where insulation or a hot roof surrounds the housing.
For solids, do not select a liquid configuration simply because its range and lens diameter look suitable. The MV-RD21G is a solids configuration. Its application review must also consider the pile and discharge profile at the proposed viewing location. A geometrically clear beam can still observe a surface that is unsuitable for the required stock indication.
Specify the electrical version before the cable schedule is frozen. A two-wire 4-20 mA/HART arrangement and a separately powered digital arrangement have different connection requirements. Use the terminal drawing for the delivered unit; a family photograph does not identify its electronics.
Inspect the completed installation before teaching false echoes
Compare the actual nozzle, antenna position and reference dimensions with the reviewed drawing. Record any changes made during fabrication. Do not hide an unreviewed reducer or a misaligned bracket by immediately adjusting suppression settings.
Then check measurement at known process conditions and follow the assigned value to the receiver. Keep the installed dimensions and final settings together. If a low-level or filling condition is unavailable at startup, record the missing observation and arrange the relevant test. For the echo investigation itself, use the radar diagnostic guide.
Installation questions
Q1. Can a long nozzle be accepted if its diameter is larger than the antenna?
Not from that dimension alone. Length, antenna position, internal steps and the required measuring range also matter. Submit a section of the assembled nozzle and the exact antenna drawing for review. A larger bore does not automatically compensate for an arbitrarily long recess.
Q2. Should the instrument always point at the vessel centre?
No. The useful position depends on the surface and obstacles. In a liquid tank, an inlet or agitator may make the centre unsuitable. In a silo, the centre may be a changing pile peak or discharge funnel. Choose the viewing area for the intended indication, then assess the complete path.
Q3. Which information is needed before the nozzle is fabricated?
Provide the tank section and plan, proposed connection, bore and length, internal structures, operating surfaces and medium. Identify uncertain dimensions explicitly. Request a configuration-specific installation drawing so the fabricator does not work from a generic product image.
Summary
Resolve the antenna position, usable measurement region and service access while the layout can still be changed. Send the proposed drawing through the METRAVON installation enquiry before committing to nozzle fabrication. For an existing vessel with adapters or a replacement instrument, the retrofit review covers the additional reference and assembly checks.
