Ultrasonic SensorsBasic knowledge about ultrasonic sensors: Features of each type of ultrasonic sensor

Here we describe the features of the various types of ultrasonic sensors (drip-proof type, high-frequency type, open structure type) offered by Murata Manufacturing. All together there are four types of ultrasonic sensors, classified by frequency and shape: the drip-proof type, high-frequency type, and open structure type (lead type and SMD type).

Drip-proof type

These are for automotive applications only. The metal case has a closed structure, allowing the sensor to be used even in environments where water may drip on it, hence the name “drip-proof type.”
These sensors are of the transmission-reception combined type, meaning that a single sensor performs both transmission and reception. The internal structure inhibits resonance.

Part number
  • NRND

(Not Recommended for New Design)

Appearance Proof Type
Frequency 58kHz
Size Φ14mm, t=9mm
Features Suitable for outdoor use, drip-proof type, low resonance
Flat directionality: 80° horizontal, 35° vertical
Applications Parking assist

High-frequency type

The high-frequency type operates at frequencies up to 300 KHz. Used for applications employing double feed detection only. Exclusive Murata technology is used to achieve broad frequency characteristics. This enables sensors to face each other at short distances in applications employing double feed detection.

Part number MA300D1-1
Appearance HF Series
Frequency 300kHz
Size Φ10mm, t=7mm
Features High resolution
Applications Double feed detection

Open structure type, lead type

The top has an open structure and inside are a unimorph piezoelectric oscillator and a horn, resulting in high sound pressure and high sensitivity. They are transmission- or reception-only and capable both short- and long-range distance detection. In addition, they can be used to detect moving objects by making use of the doppler effect to detect fluctuations in the received waveforms. Due to the open structure, they are suitable for indoor use only.

Part number MA40S4R(For reception)MA40S4S(For transmission)
Frequency 40kHz
Size Φ10mm、t=7mm
Features For indoor use, high sound pressure and high sensitivity
Applications Distance detection/object (moving object) detection

Open structure type, SMD type

Compact and low-profile configuration suitable for surface mounting. Transmission-reception combined type, allowing for distance detection in confined spaces.

Part number MA40H1S-R
Frequency 40kHz
Size 5.2×5.2mm, t=1.2mm
Features Compact, suitable for surface mounting
Applications Distance detection and object detection