Extech Instruments EMF450 User Manual

EMF450-en-GB_V1.4 7/17
4
Definitions
 Electromagnetic Radiation
This meter is used to indicate radiated electromagnetic fields wherever there is a voltage,
current, electric (E) or magnetic (H) field. Examples include the electromagnetic fields from
radio broadcasting, TV transmitters and power lines.
 Electric Field Strength
This is a field vector quantity that represents the force (F) on an infinitesimal unit positive
test charge (q) at a point divided by that charge. Electric field strength is expressed in units
of volts per meter (V/m). Use the units of electric field strength for measurements in near-
field power measurements.
 Magnetic field strength (H)
This is a field vector that is equal to the magnetic flux density divided by the permeability of
the medium. Magnetic field strength is expressed in units of amperes per meter (A/m).
This measurement is for near-field power measurements.
 Power density (S)
Power per unit area in the direction of propagation; usually expressed in units of watts per
square meter (W/m2) or, for convenience, milli-watts per square centimeter (mW/cm
2
).
 The characteristic of electromagnetic fields
Electromagnetic fields propagate as waves and travel at the speed of light (c).
The wavelength is proportional to the frequency.
λ (wavelength) =
c (speed of light)
f (frequency)
Near-field is assumed if the distance to the field source is less than three wavelengths. For
far-fields, the distance is more than three wavelengths. In the near-field, the ratio of
electric field strength (E) and magnetic field strength (H) is not constant, so measure each
separately. In the far-field, however, it is enough to measure one field quantity, and
compute the other accordingly.
Descriptions
Front Panel Description
1. 2.4” Color TFT display (240*320 resolution)
2. Select and Down button
3. Power and Menu button
4. Hold and Enter button
5. Battery compartment cover and
measurement chart on back of meter
Figure 1 – Meter Description

Extech Instruments EMF450 Specifications

General

Sensor Type	LF - Magnetic Fields, LF- Electric Field Sensor, RF Strength
Range	20mG /200mG /2000mG, 2µT /20µT /200µT, 50V/m to 2000V/m, 0.02µW/m² to 554.6mW/m²
Display resolution	0.02/0.1/1, 1V/m, 0.02µW/m², 0.2µA/m, 0.2mV/m, 0.002µW/cm², 2dB
Frequency range	50/60Hz, 50/60Hz, 50MHz to 3.5GHz
Accuracy	± (15% + 100 digits), ± (7% + 50 digits), ± 2dB at 2.45GHz
Display	4 digits Triple color TFT display
Sample rate	6 seconds
Sensors	Triple axes (XYZ) ELF and RF and Electric field sensor
Battery	Three (3) 1.5V alkaline batteries
Battery Life	Approx. 8 hours
Operating temperature and RH%	5°C~40°C (41°F ~104°F); < 80%RH
Storage temperature and RH%	-10°C to 60°C (14°F ~140°F); < 70%RH

Weight and Dimensions

Weight	Approx. 120g (4.2 oz.)
Dimensions	115 x 60 x 21mm (4.5 x 2.4 x 0.08”)