Extech Instruments 480846 User manual

RF EMF Strength Meter

Model 480846

User's Guide

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Safety Information

CAUTION

Before making a measurement, check if the low battery symbol (

display when the meter is switched on. Replace the battery if t he 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.

+

) is shown on the

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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.

(wavelength) =

Near-field is assumed if the distance to the field source is less than three wavelengths. For far­fields, 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 just measure one field quantity, and compute the other
accordingly.

c (speed of light)

f (frequency)

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Description

Front Panel Description

(1). E-field sensor.

(2). LCD display.

(3). MAX/AVG

Press this key to scroll through the following:

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

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

(5). UNIT

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

or mA/m” “ W/m2, mW/m2 or W/m2” “ W/cm2 or
mW/cm2””

Press and hold this key while turning the meter on to disable

the audible sound. The “

(6). TIME ALARM key:

Press this key to display date and time.
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.

Press this key for 3 seconds to switch alarm function On or

Off.

(7). XYZ Cal key:

Press this key to change the sensor axis: “All axis” “X

axis” “Y axis” “Z axis”.

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:

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

(9 - 12).

value, calibration factor setting value, or recall data.

(10). MEM key:

Press this key one time to store one data set to memory.
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:

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

mode.

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

The “ ” symbol will disappear

keys

: Used to set current date and time, datalogging interval time, alarm setting

” symbol will disappear.

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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).+ : Low battery indication.

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

A/m and mA/m : Magnetic field strength.;

W/m2, mW/m

Power density

(7). : Measured value displayed as per selected mode and selected units.

(8). : Stored measured value to memory indication.

(9). : Manual data memory mode indication.

(10). : 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.

(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.

2,

2,

W/m

W/cm2 and mW/cm2:

: YY : MM : DD Date displayed.

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Operation

E-field sensors

The 3-channel sensor is located at the top of the meter. The three voltages generated by the sensor
are fed back to the meter. In far-fields, an E-field sensor is preferable due to the greater bandwidth.
The E-field sensor specific calibration accurate frequency ranges are 900MHz, 1800MHz, 2.7GHz,

3.5GHz and 8GHz. Other measurements can be made, for reference purposes only, using the entire
range of 10MHz to 8GHz.

The meter is a small portable instrument that measures the electric field in the atmosphere of the
sensor’s surroundings. The measurement of the field is done by moving the aerial of the sensor in the
desired measured environment.

A direct wide band measurement is obtained of the field that the measurement sensor is
subjected to. To find the value of the field emitted by a source of interference, simply point the
aerial towards it and get as close as possible (the value of the field is inversely proportional to the
distance of the sensor/emission source). The operator must take care not to be between the
source of disturbance and the zone to be checked. The human body shields electromagnetic
fields. The E-field sensor is isotropic; it does not require special handling. It measures the field
according to 3 axes without the aerial having to be moved in the 3 planes. Simply point it at the
target to make the measurement.

Explanatory notes

Units of measurement

The meter measures the electrical component of the field; the default units are those of electrical field
strength (mV/m, V/m). The meter converts the measurement values to the other units of measurement,
i.e. the corresponding magnetic field strength units ( A/m, mA/m) and power density units ( W/m2,
mW/m2, W/m2, W/cm2 or mW/cm2) using the standard far-field formulate for electromagnetic radiation.
The conversion is invalid for near-field measurements, as there is no generally valid relationship
between electrical and magnetic field strength in this situation. Always use the default units of the
sensor when making near-field measurements.

Result modes

The bar graph display always shows each axis (X, Y or Z) the instantaneous measured dynamic
range value. The digit display shows the measurement according to one of four selectable
modes:

Instantaneous: The display shows the last value measured by the sensor, no symbol is
displayed.(RMS Value)
Maximum instantaneous (MAX): The digital display shows the highest instantaneous value
measured, the “MAX” symbol is displayed.(PEAK Value)

Average (AVG): The digital display shows the average value measured, the “AVG” symbol is
displayed. (RMS Value)
Maximum average (MAX AVG): The digital display shows the highest average value
measured, the “MAX AVG” symbol is displayed. (PEAK Value)

Field strength

Max. Hold

Max. Average

Average

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Actual

t

Alarm Limit Value (ALARM)

The alarm limit value is used to monitor the display value automatically. It controls
alarm indication function. The alarm limit value can be edited in the display V/m unit.

NOTE:Alarm Limit Function is only used for total three axial value comparator.

Setting the units of measurement

Press the UNIT key to step through the units display.

(

)

a

b

)

(

(

d

UNIT

)

UNIT

c

)

(

(a). Electric field strength (V/m).
(b). Computed magnetic field strength (mA/m).
(c). Computed power density (mW/m2).
(d). Computed power density ( W/cm2).

Setting the result mode

Instantaneous result mode is automatically set when the meter is turned on.
Press the MAX/AVG key to step through the results displays:

UNIT

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Setting the alarm limit value (ALM)

Power off

Hold-on

+

1. Press key to turn off the meter.

2. Press and hold the TIME ALARM key, then press key to turn on the meter, the display

then shows “ALM” and “ ” (The Alarm setting mode). The four flashing digits can now be
changed.

3. Press or key to increase or decrease the value.

4. Press SET to store the new setting value and exit.

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Setting the alarm function on or off

1. Press ALARM key for 2 seconds to switch the alarm function on or off. The “ALM” and

“

” symbols in the display indicates that the alarm function is on.

2. When the alarm function is on, the display will show “ ” if the instantaneous measured
value exceed the limit value.

Setting the audible sound function off

When the meter is normally turned on, the audible sound function is on.

1. Press key to turn off the meter.

2. Press and hold

” symbol will disappear from the display.

MAX/AVG

key and turn on the meter again to disable the audible sound, the “

Setting the auto power off function off

When the meter is normally turned on, the auto power off function is on.

1. Press key to turn off the meter.

2. Press and hold

function; the “ ” symbol will disappear from the display.

READ

key and turn on the meter again to disable the auto power off

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Making measurements

Important:

If the sensor is moved quickly, excessive field strength values will be displayed which do not
reflect the actual field conditions. This effect is caused by electrostatic charges.

Recommendation:

Hold the meter steady during the measurement.

Short-term measurements

Application:

Use either the “Instantaneous” or the “Max. Instantaneous” mode if the characteristics and
orientation of the field are unknown when entering an area exposed to electromagnetic
radiation.

Procedure

1. Hold the meter at arm’s length.

2. Make several measurements at various locations around the work place or the
interested areas as described above. This is particularly important if the field conditions
are unknown.

3. Pay special attention to measuring the neighboring vicinity for possible radiation sources.
Apart from active sources, those components connected to a source may also act as
radiators. For example, the cables used in diathermy equipment may also radiate
electromagnetic energy. Note that metallic objects within the field may locally concentrate
or amplify the field from a distant source.

Long-term exposure measurements

Location:

Place the meter between yourself and the suspected source of radiation. Make measurements
at those points where parts of your body are nearest to the source of radiation.

Note: Use the “Average ” or “Max average” modes only when the instantaneous measurement
values are fluctuating greatly.

Alarm function

Use this feature in the “Instantaneous”, “Max. Instantaneous”, “Average” or “Max. Average”
modes.

When the instantaneous measured value exceeds the limit value, a sequence of warning beeps
will sound.

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Data memory

The meter includes a non-volatile data memory that can store a maximum of 99 measured
values.

Storing individual measured values

The current memory location number appears in the lower right small display.
Once you press the MEM key, it will store a displayed value and increment the memory location
by one. Each flash of the “ ” symbol display indicates one reading has been stored. When the

memory location number shows “99”, to indicate the manual data memory is full, the user must
clear the entire contents of the data memory before storing new values.

Reading individual measured values

Entry

Reading mode indicate

Reading memory location

Exit

1. Press READ key, the display shows “ ”(reading mode).

2. Press or key to select the desired memory location.

3. Press the UNIT key to select the desired reading units.

4. Press the XYZ/CAL key to select the desired sensor axis reading.

5. Press the READ key to exit.

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Deleting stored values

Once the memory is full, the entire contents of the memory can be cleared.

1. Press to turn off the meter.

2. Press and hold MEM and turn on the meter again; the display will shows:

“ ” and “ ”.

3. Press to select “ . ”.

4. Press SET to clear memory and exit.

Setting Current Data and Time

1. Press the SET key to enter this mode, the “SEt” mark is displayed.

2. Press o r key to move flashing two digit to desired setting position “hh:mm:ss” or
“YY/MM/DD”.

3. Press or keys to set the current time “hh:mm:ss” and current date “YY/MM/DD”.

4. Press the SET key to store setting value and exit.

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Calibration Factor (CAL)

The Calibration factor (CAL) provides a means to improve the accuracy of the results display by calibrating
against the output of a known frequency generator. The field strength value measured is multiplied by the
value of CAL that has been entered and the resulting value is displayed. The CAL setting range is from 0.20
to 5.00. The measurement accuracy will be sufficient for most applications even if the frequency response of
the sensor calibration factor is ignored and the CAL is set to 1.00 in at all points.

Setting the calibration factor (CAL)

Power off

Hold-on

+

When the meter is normally turned on, the calibration factor set value will display for 2 seconds.

1. Press key to turn off the meter.

2. Press and hold on the XYZ/CAL key, then press key to turn on the meter to enter the

calibration factor setting mode, the “ CAL SEt ” marks is displayed.

3. Press or key to increase or decrease the value.

4. Press the SET key to store the new setting value and exit.

E-Field Typical Calibration Data:

Frequency CAL Frequency CAL

50MHz 2.13 900 MHz 1.40

100MHz 1.37 1.8GHz 2.06

200 MHz 1.19 2.4GHz 0.66

300 MHz 0.69 3.5GHz 1.05

433 MHz 0.78 5.4GHz 2.20

500 MHz 1.38 8.0GHz 3.16

600 MHz 2.12

700 MHz 1.66

800 MHz 1.40

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Battery Installation and Replacement

Battery Installation

Remove the rear battery cover and insert a fresh 9V battery.

Battery Replacement

When the battery voltage drops below the operating voltage, the battery icon

flashes. If it appears, the battery should be replaced.

You, as the end user, are legally bound (
accumulators;

You can hand over your used batteries / accumulators at collection points in your community
or wherever batteries / accumulators are sold!

disposal in the household garbage is prohibited!

Battery ordinance

+

appears and

) to return all used batteries and

Disposal:

end of its lifecycle

Follow the valid legal stipulations in respect of the disposal of the device at the

Specifications

General Specifications

Measurement method

Directional characteristic

Measurement range selection

Display resolution

Setting time

Display refresh rate

Display type

Audible alarm

Units

: mV/m, V/m, A/m, mA/m, W/m2, mW/m2, W/m2W/cm2,

Display value

Alarm function

D

ata memory and read storage

Dry batteries

Battery life

Auto power off

Operating temperature range

Operating humidity range

Storage temperature range

Storage humidity range

Dimensions

Weight (including battery)

: 0.1mV/m, 0.1 A/m, 0.1 W/m2, 0.001 W/cm

: T Typically 1s (0 to 90% of measurement value).

: Liquid-crystal display (LCD), 4 digit.

: Buzzer.

: Instantaneous measured value, maximum value, or

: Adjustable threshold with ON/OFF.

: 9V NEDA 1604/1604A

: > 3 hours

: 5 minutes.

: Approx. 67(W) 60(T) 247(L)mm.

: Digital, triaxial measurement.

: Isotropic, triaxial.

: One continuous range.

: Typically 0.5 seconds

2

mW/cm

maximum average value.

: 99 data sets.

: 0°C to +50°C

: 25% to 75%RH

: -10°C to +60°C

: 0% to 80%RH

: Approx. 250g

2

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Electrical Specifications

Unless otherwise stated, the specifications hold under the following conditions:

The meter is located in the far-field of a source, the sensor head is pointed towards the source.

Ambient temperature: +23C 3C

Relative air humidity: 25% to 75%

Sensor type: Electrical field (E)

Frequency range: 900MHz, 1800MHz, 2.7GHz, 3.5GHz and 8GHz

Specified measurement range:
CW signal (f > 900MHz): 20mV/m to 108.0V/m

Dynamic range: Typically 75dB

Absolute error at 1 V/m & 900 MHz: 1.0dB

Frequency response:

Sensor (with typical CAL factors): 1.0dB (50MHz to 1.9GHz)

Isotropy deviation: Typically 1.0dB (f>900MHz)

Overload limit: 10.61mW/cm2 (200V/m)

Thermal response (0 to 50°): 0.5dB

(measurements can be made, for reference purposes
only, using the entire range of 10MHz to 8GHz

53 A/m to 286.4mA/m
1 W/m2to 30.93W/m
0 W/cm2to 3.093mW/cm

2.4dB (1.9GHz to 8GHz)

2

2

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Copyright © 2014 FLIR Systems, Inc.

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