Extech 480846 Operating Manual

User's Guide

RF EMF Strength Meter

Model 480846

Safety Information

CAUTION

• Before making a measurement, check if the low battery symbol ( + ) is shown on the display when the meter is switched on. Replace the battery if the symbol is displayed.

• In the case of prolonged storage, it is preferable to remove the battery from the meter.

• Avoid shaking the meter, particularly in the measurement mode.

• The accuracy and function of the meter may be adversely affected by

exceeding the specified limits as well as by improper handling.

DANGER!

• Use caution when working in the vicinity of powerful radiation sources.

• Persons with electronic implants (e.g. cardiac pacemakers) should avoid

powerful radiation sources.

• Observe the local safety regulations.

• Observe the operating instructions for equipment that is used to generate or

conduct electromagnetic energy.

• Be aware that secondary radiators (e.g. reflective objects such as a metallic fence) can cause a local amplification of the field.

• Be aware that the field strength in the near vicinity of radiators increases

proportionally to the inverse cube of the distance. This means that enormous field strengths can result in the immediate vicinity of small radiation sources (e.g. leak in waveguides, inductive ovens).

• Field strength measuring devices can underrate pulsed signals, particularly with radar signals in which case significant measurement errors can arise.

• All field strength measuring devices have a limited specified frequency range.

Fields with spectral components outside of this frequency range are generally incorrectly evaluated and tend to be underrated. Before using field strength measuring devices, you should thus be certain that all field components to be measured lie in the specified frequency range of the measuring device.

480846 V2.3 7/09

Introduction

This meter is a broadband device for monitoring high-frequency radiation in the range of 10MHz to 8GHz. The non-directional electric field and high sensitivity also allow measurements of electric field strength in TEM cells and absorber rooms.

The unit of measurement and the measurement types are expressed in units of electrical and magnetic field strength and power density.

At high frequencies, the power density is of particular significance. It provides a measure of the power absorbed by a person exposed to the field. This power level must be kept as low as possible at high frequencies. The meter can be set to display the instantaneous value, the maximum value measured or the average value. Instantaneous and maximum value measurements are useful for orientation, e.g. when first entering an exposed area.

 10MHz to 8 GHz Frequency range.

 For isotropic measurements of electromagnetic fields.

 Non-directional (isotropic) measurement with three-channel measurement sensor.

 High dynamic range due to three-channel digital processing.

 Configurable alarm threshold and memory function.

Fundamentals

 Electromagnetic Radiation

This meter is used to indicate radiated electromagnetic fields. Wherever there is a voltage or a current, electric (E) and magnetic (H) fields arise. Examples include the electromagnetic fields from radio broadcasting and TV transmitters.

 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 the following situations:

• In the near-field area of the source.

• Where the nature of the electromagnetic field is unknown.

 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).

 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, units such as milliwatts per square centimeter (mW/cm2).

 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 nearfield, 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 just measure one field quantity, and compute the other accordingly.

480846 V2.3 7/09

Description

Front Panel Description

(1). E-field sensor.

(2). LCD display.

(3). MAX/AVG

c Press this key to scroll through the following:

“Instantaneous”→ “Max. instantaneous” → “Average” → “Max. average”.

key: Press this key to turn the meter on or off.

(4)

(5). UNIT

c Press this key to change the units: “mV/m or V/m”

→ “μA/m or mA/m” → “μW/m

“μW/cm

d Press and hold this key while turning the meter on

to disable the audible sound. The “ will disappear.

(6). TIME ALARM key:

c Press this key to display date and time. d Press and hold this key while turning the meter

ON to the alarm setting mode, press the SET key 2 times to exit this mode.

e Press this key for 3 seconds to switch alarm

function On or Off.

(7). XYZ Cal key:

c Press this key to change the sensor axis: “All axis” → “X axis” → “Y axis” → “Z axis”. d Press and hold this key while turning the meter on to switch the device to the

calibration factor setting mode, press SET key to exit this mode.

(8). SET key:

c Press this key to enter the current data and time setting mode. Press again to exit.

(9 - 12). STWX keys : Used to set current date and time, datalogging interval time,

alarm setting value, calibration factor setting value, or recall data.

(10). MEM key:

c Press this key one time to store one data set to memory. d Press and hold this key while turning the meter on to enter the clear manually

recorded data mode. Press SET key to exit this mode.

(11). READ key:

c Press this key to switch to the manual data reading mode. Press this key again to exit

this mode.

d Press and hold this key while turning the meter on to disable the Auto Power OFF

function. The “

or mW/cm2””

” symbol will disappear

, mW/m2 or W/m2”→

” symbol

480846 V2.3 7/09

LCD display description

(1). : Auto power off function on / off.

(2).

: Audible sound function on / off.

(3). MAX: Maximum measured value displayed.

MAX AVG: Maximum average value displayed.

(4). AVG: Average measured value displayed.

(5).

(6). Units : mV/m and V/m : Electric field strength;

: Low battery indication.

μA/m and mA/m : Magnetic field strength.; μW/m

, mW/m

W/m

μW/cm2 and mW/cm2:

Power density

(7).

(8).

(9).

(10).

: Measured value displayed as per selected mode and selected units.

: Stored measured value to memory indication.

: Manual data memory mode indication.

: Manual data memory address number (1~99).

(11). ALM: Alarm function on / off or alarm setting indication.

(12). ▲ : Displays when the alarm function is on and the instantaneous measured value

exceeds the limit value indication.

(13).

: hh : mm : ss Time displayed.

: YY : MM : DD Date displayed.

(14). CAL : Calibration factor indication or setting indication (from 0.20 to 5.00).

(15). Z : Z axis measured value displayed.

(16). Y : Y axis measured value displayed.

(17). X : X axis measured value displayed.

(18).

: Analog bargraph of each axis (X,Y or Z) measured dynamic range

indication for observing trends.

480846 V2.3 7/09

+ 11 hidden pages