Extech Instruments 480846 User Manual

480846 V2.3 7/09
3
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 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.

Extech Instruments 480846 Specifications

General

Model	480846
Resolution	0.1 dB
Power Source	9V battery
Measures	Sound Level
Data Hold	Yes
Min/Max	Yes
Frequency Response	31.5 Hz to 8 kHz
Weighting Networks	A and C
Display	LCD
Time Weighting	Fast/Slow
Temperature Range	32 to 122°F (0 to 50°C)

Summary

Safety Information

General Safety Precautions

Important warnings regarding battery, handling, and general precautions.

Radiation Safety & Measurement Notes

Critical safety advice for radiation sources and measurement conditions.

Introduction

Fundamentals of EMF Measurement

Explains concepts like electromagnetic radiation, electric/magnetic fields, and power density.

Description

Front Panel Overview

Details the E-field sensor, LCD display, and operational buttons on the meter's front panel.

LCD Display Description

Operation

E-Field Sensor Functionality

Describes the 3-channel sensor and its role in measuring electric fields.

Measurement Explanations

Details units of measurement and different result modes (Instantaneous, Max, Avg).

Alarm Limit Value (ALARM)

Setting Measurement Units

Explains how to cycle through and select different units for measurement display.

Setting Result Modes

Describes how to switch between instantaneous, maximum, and average measurement displays.

Setting the Alarm Limit Value

Setting the Alarm Function

Setting Audible Sound

Setting Auto Power Off

Making Measurements

Short-Term Measurement Procedures

Guidelines for taking quick measurements and identifying field characteristics.

Long-Term Exposure Measurement

How to set up the meter for extended monitoring of radiation exposure.

Using the Alarm During Measurements

How the alarm function alerts the user to exceedance of set limit values.

Data Memory Functions

Storing Measured Values

How to save individual readings to the meter's internal memory.

Reading Stored Values

Procedure to access and review data previously stored in memory.

Deleting Stored Data

Setting Current Date and Time

Calibration Factor (CAL)

Setting the Calibration Factor

How to adjust the calibration factor to improve measurement accuracy.

Battery Management

Specifications

General Specifications

Lists general operating parameters, measurement types, and physical characteristics of the meter.

Electrical Specifications

Warranty Information

Calibration and Repair Services