NBM-550 Broadband Field Meter

Compact Hand Held Device with Data Logging Function for Measuring Electric and Magnetic Fields. 

The Narda Broadband Field Meter NBM-550 is part of the NBM-500 device family. It makes extremely accurate measurements of non-ionising radiation.
Equipped with probes for measuring electric and magnetic field strengths, it covers all frequencies from long wave up to microwave radiation. Flat frequency response probes (“flat probes”) as well as so-called shaped probes that evaluate the field strength on the basis of a human safety standard are available. These probes are calibrated separately from the field meter, and include a non-volatile memory that contains the probe parameters and calibration data. They can therefore be used with any device in the NBM-500 family without losing any of the calibration accuracy.
The NBM-550 is used to make precision measurements to establish human safety, particularly in workplace environments where high electric or magnetic field strengths are likely to occur.

For more information on the NBM-550 Broadband Field Meter, contact your local Air-Met office. 
  • Non-directional measurement using isotropic probes for applications in the frequency range 5 Hz to 60 GHz
  • Intelligent probe interface detects probe parameters
  • Fully automatic zero point adjustment
  • Memory for saving up to 5,000 measurement results
  • PC software for convenient data management


  • GPS interface and plug-in GPS receiver for automatically storing the position data
  • Voice recording for comments
  • Conditional logging: Measured value saved when a threshold value is exceeded
Display Type Transflective LCD, monochrome
Display Size 10 cm (4“), 240 x 320 dots
Backlight White LEDs, selectable illumination time (OFF, 5s, 10s, 30s, 60s, PERMANENT)
Refresh Rate 200 ms for bar graph and graphics, 400 ms for numerical results
Operating Languages English, French, German, Italian, Spanish, Simplified Chinese, Turkish, Russian
MEASUREMENT FUNCTIONS (with high frequency probes)
Result Units mW/cm2, W/m2, V/m, A/m, % (of standard)
Display Range .0001 to 9999, 4 digits, variable or fixed triads can be selected
  Variable Triads Fixed Triads
  0.01 V/m to 100.0 kV/m 0.01 to 9999 V/m
  0.01 mA/m to 265.3 A/m 0.0001 to 265.3 A/m
  0.001 mW/m2 to 26.53 MW/m2 0.0001 to 9999 W/m2
  0.1 nW/cm2 to 2.653 kW/cm2 0.0001 to 9999 mW/cm2
  0.0001 % to 9999 % 0.0001 to 9999 %
Result Types (isotropic, RSS) Actual, Maximum, Minimum, Average, Average Maximum
Result Types (X-Y-Z mode) Actual X, Actual Y, Actual Z (requires a probe with separate axes)
Time Averaging Selectable averaging time, 4 s to 30 min (2 s steps)
Spatial Averaging Discrete or continuously
Multi-Position Spatial Averaging Averages up to 24 spatially averaged results, each position and total is stored
History Mode Graphical display of Actual results versus time (span of 2 minutes to 8 hours)
Correction Frequency 1 kHz to 100 GHz or OFF (direct frequency entry, interpolation between calibration points)
Hot Spot Search Audible indication of increasing and decreasing field strength (result type Act or Max)
Alarm Function 2 kHz audible signal (4 Hz repetition), adjustable threshold
Timer Logging Start time pre-selection: up to 24 h or immediate start
Logging duration: up to 100 h
Logging interval: 1s to 6 min (in 11 steps)
Physical Memory 12 MB non-volatile flash memory for measurement results and voice comments
Storage Capacity Up to 5000 results (including instrument settings, time stamp and GPS data when available)
Remote Control Via USB or optical RS-232 interface (selectable)
USB: Serial, full duplex, 460800 baud (virtual COM port), multi-pin connector
Optical Interface: Serial, full duplex, 115200 baud, no parity, 1 start and 1 stop bit
Earphone 3.5 mm TRS, ≥ 16 ohms (mono), for voice recorder option only
External Trigger (for result storage) Uses the multi-pin connector. Interface cable with BNC connector available as accessory
Triggers when contacts short-circuited
External GPS Receiver Uses the multi-pin connector; GPS receiver with interface cable available as an option
Probe interface
Plug-and-play auto detection, compatible with all NBM series probes
Integration time for measuring input approx. 270 ms
Measurement sampling rate 5 Hz (5/ 50/ 60 Hz for remote operation)
  • Measuring field strengths to comply with general safety regulations
  • Establishing safe zones
  • Measuring and monitoring field strengths around broadcasting and radar equipment
  • Measuring field strengths of cell phone transmitters and satellite communications systems to demonstrate compliance with human safety standard limit values
  • Measuring field strengths in the industrial environment, such as plastics welding equipment, RF heating, tempering, and drying equipment
  • Measurements for protecting users of diathermy equipment and other medical devices that generate high-frequency radiation
  • Measuring field strength in TEM cells and absorber chambers to demonstrate electromagnetic compatibility (EMC)
  • Spectral measurements on LF fields emanating from industrial equipment or overhead power cables