//bat.bing.com/action/0?ti=5562332&Ver=2 Ultrasonic and Radar Level Sensor Information

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Ultrasonic and Radar Level Sensor Information

Radar Sensor Technology

If a Madison ultrasonic sensor can't measure the level of your liquid, our radar sensors can. Madison's radar sensors can detect the liquid level under a layer of airy foam and even can measure Oil/Water interfaces.

Internal piping, deposits on the antenna, multiple reflections or reflections from the wall can all interfere with the proper operation of the radar sensor. Madison's radar sensors use improved microwave pulse technology to track any target material from the tip of its antenna to the bottom of the tank. Their power, pulse widths and sensitivity depend on the distance of the target from the antenna and the dielectric constant of the reflecting material.

Madison's radar sensors feature "echo marker" signal processing, making them among the most technologically advanced pulse radar systems on the market. 

This technology will provide a reliable continuous pulse shape unaffected by environmental conditions such as:

  • Temperature
  • Vacuums
  • Pressure
  • Methane
  • Vapors
  • CO2
  • Steam
  • Condensation
  • Wind

The antenna is offered in Polypropylene or an optional high-resistance PTFE (Teflon®) that can help provide resistance to material buildup.

Simple mounting and push-button calibration make for a very easy installation. Calibration can be completed on the bench or in the field by following simple instructions. The sensor can be threaded directly into a 2" NPT metal or plastic flange. Unique application requirements can be described on the Madison Specification Work Sheet, which our engineering department will use to produce a design that meets your needs.

Refer to the Product Data Sheet for specific product operation characteristics, or contact a Madison representative for further information.

Architecture of a Radar Level Sensing Device:


Operation Principle of Microwave Level Devices:


The microwave rod antenna is stimulated by an electromagnetic pulse transmitter and sends very short pulses to a target. The pulses reflect from the target and then they are received back by the same antenna. The electrical signal from the antenna is amplified and processed. The distance to an object is calculated and then converted to 4-20 mA. Optionally, level information is also sent to a PC via RS232 or RS485 for diagnostic data logging and programmable set-up.

Operation Note:

Turning the low dielectric materials operation mode ON or OFF

The ON mode is recommended for materials with a dielectric constant lower than 4 and to eliminate multiple reflections in tanks.

  1. To turn the low dielectric materials mode ON, push the calibration button and hold until the LED light flashes yellow, then red, and then turns off. Release the button. The blinking green LED light indicates that the low dielectric materials mode is ON.
  2. To turn the low dielectric materials mode OFF, push the calibration button and hold until the LED light flashes yellow, then red, then turns off. Release the button. The constant green LED light indicates that the low dielectric materials mode is OFF.

The low dielectric materials operation can also be turned ON or OFF with Madison's software during PC communications, which is recommended.

Radar Sensor Still-Pipe Mounting Considerations:

No end cut is required for the following:

Pipe ID Max.
2.0" 2.5"
3.0" 3.5"
4.0" and 5.0" 6.0"
6" 10.5"

End cut of 45° is required for pipes longer than 10.5"; the ID of the pipe must be greater than 6".

FCC Information for Users

Sensors have been tested and found to comply with the limits for Class A digital device, pursuant to Part 15 of the FCC rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operating in a commercial environment. These sensors generate, use, and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause interference with radio communications. Operation of this equipment in a residential area is likely to cause interference that the user will be required to correct.

Radar features: 

Madison Company's radar sensors are highly accurate, noiseless and self-adjusting pulse radar transmitters for distances up to 100'. The sensors adjust their microwave pulse amplitude and width to a target distance and target reflection properties. The receivers change their sensitivity with the amplitude of received echoes. In addition, the sensors analyze the shapes of the received echoes and eliminate the ones coming from tank walls, standpipes and other obstructions. These features allow the sensors to track any wanted target from the tips of their rod antennas to the bottom of the tank, regardless of the tank shape or environmental conditions. For very low dielectric constant materials (≈ 2), the radar sensor needs at least 2' from the antenna tip to detect the material. Any buildup on the rod antennas does not deteriorate the performance of the radar sensors. The radar transmitters do not have any mismatch between resonator and transceiver. This eliminates problems when a target is close to the antenna and gives optimal performance of the radar sensor's very high efficiency. The Madison radar sensors also feature a low dielectric mode. In this mode, the Madison sensors will ignore echoes from tank bottoms with material present, and they will increase their transmit energy and the sensitivity of their receivers until they detect echoes from the surfaces of the low dielectric materials. This mode will work with dielectrics around 2 and higher.