Free Space Radar Level Transmitter

This device is a non-contact radar level transmitter that uses FMCW technology. It measures distance, level and volume of powders, granulates and other solids. It is ideal for measuring the level of solids in applications with very dusty atmospheres.

Highlights

2-wire loop-powered 80 GHz transmitter – HART® 7
Accuracy: ±2 mm / ±0.08 ̈
PEEK Lens antenna options include:
DN70 / 23⁄4 ̈ antenna with 4° beam angle suitable for long nozzles and distances up to 100 m / 328 ft
DN40 / 11⁄2 ̈ antenna with 8° beam angle, available with 11⁄2 ̈ thread connections, measures up to 30 m / 98 ft
112 mm / 4.4 ̈ antenna extension for long nozzles
One user interface for all applications
Antenna purging system for flange connection without antenna extension
Empty tank spectrum function eliminates false reflections caused by tank internals
Extensive choice of process connections (threaded ≥11⁄2 ̈ and flange ≥DN50 / 2 ̈)
Extremely high dynamics with considerable signal-to-noise ratio for clear vision in dusty atmospheres
4 GHz sweep for high resolution
Low-cost low-pressure disc flange
No need for antenna aiming kits. A slanted flange can be installed if necessary.

Industries

Metals, Minerals & Mining
Chemical market
Power

Agri-food
Wastewater
Pulp & Paper

Applications

Buffer silos
Buffer silos
Bulk storage containers or hoppers

Applications

Level measurement of solids

The level transmitter can measure the level of a wide range of solid products on a large variety of installations within the stated pressure and temperature range. It does not require any calibration: it is only necessary to do a short configuration procedure.

Mass (volume) measurement

This data permits the device to calculate (by linear interpolation) volume or mass between strapping table entries. PACTwareTM software and a DTM (Device Type Manager) is supplied free of charge with the device. This software permits the user to easily configure the device with a computer.

Measuring principle

A radar signal is emitted via an antenna, reflected from the product surface and received after a time t. The radar principle used is FMCW (Frequency Modulated Continuous Wave).
The FMCW-radar transmits a high frequency signal whose frequency increases linearly during the measurement phase (called the frequency sweep). The signal is emitted, reflected on the measuring surface and received with a time delay, t. Delay time, t=2d/c, where d is the distance to the product surface and c is the speed of light in the gas above the product.
For further signal processing the difference Δf is calculated from the actual transmitted frequency and the received frequency. The difference is directly proportional to the distance. A large frequency difference corresponds to a large distance and vice versa. The frequency difference Δf is transformed via a Fast Fourier Transform (FFT) into a frequency spectrum and then the distance is calculated from the spectrum. The level results from the difference between the tank height and the measured distance.

Technical data

Measuring system

Measuring principle	2-wire loop-powered level transmitter; FMCW radar
Frequency range	W-band (78...82 GHz)
Max. radiated power (EIRP)	< -41.3 dBm according to ETSI EN 307 372 (TLPR) and ETSI EN 302 729 (LPR)
Application range	Level measurement of powders and granulates
Primary measured value	Distance and reflection
Secondary measured value	Level, volume and mass

Design

Options
Construction	The measurement system consists of a measuring sensor (antenna) and a signal converter
	Integrated LCD display (-20..+70°C / -4...+158°F); if the ambient temperature is not in these limits, then this condition can stop the display
	Distance piece (for process temperature: +150...+200°C / +302...+392°F)
	Antenna purging system (supplied with a G 1/4 connection)
	Weather protection
Max. measuring range
	Lens, DN40 (11⁄2 ̈): 30 m / 98 ft
	Lens, DN70 (23⁄4 ̈): 100 m / 328.1 ft
	Refer also to "Measuring accuracy" on page 16
Min. tank height	1 m / 40 ̈
Recommended minimum blocking distance	0.3 m / 12 ̈ (add 112 mm / 4.4 ̈ if the DN40 Lens antenna has an antenna extension)
Min. distance for reflection measurement	1 m / 3.3 ft
Beam angle (antenna)
	Lens, DN40 (11⁄2 ̈): 8°
	Lens, DN70 (23⁄4 ̈): 4°