User manual

ManualsBrandsGIGAHERTZ SOLUTIONS ManualsRadiation MeasurementHF 38B High frequency (HF)-Analyser, Electric smog meter, 800 - 2500 MHz (3300 MHz/-3 dB), includes

Digitaler Hochfrequenz Analyser HF38B

GHz cordless phones the ratio can be as

high as 1:100.), the higher the potential con-

tribution from a 2.4-GHz cordless phone sig-

nal to the total maximum value or the less

channels are being used by cellular phone

users.

Still today, some field meters only display

average values. They are of little help when

considering the potential health risks associ-

ated with pulse-modulated RF radiation be-

cause through the „averaging“ of steep RF

pulses, RF radiation exposure can be under-

rated up to a factor of 100 such as in 2.4-

GHz cordless phones.

Actual Measurements

Now the antenna is attached again to the

RF analyzer because objects (mass) directly

behind the RF analyzer also have an effect on

the testing result. Hold the RF analyzer with a

slightly outstretched arm. Your hand

should not reach too close to the antenna,

but stay near the bottom end of the RF ana-

lyzer.

In the area of a local maximum the position-

ing of the RF analyzer should be changed

until the effective power density (the most

interesting measurement value) can be lo-

cated. This can be achieved as follows:

- Through scanning „all directions“ to locate

the direction from which the major RF

emission(s) originate. Move your wrist from

right to left. For emission sources behind

your back, you have to turn around and

place your body again behind the RF ana-

lyzer.

- Through rotating the RF analyzer with at-

tached antenna around its longitudinal axis

to consider the polarization plane of the RF

radiation.

- Through changing the measurement posi-

tion („measurement spot“) to avoid meas-

uring exclusively in one spot, which might

accidentally have local or antenna-specific

cancellation effects.

Some manufacturers of field meters propa-

gate the idea that the effective power density

should be obtained by taking measurements

of all three axes and calculating the resultant.

Most manufacturers of professional testing

equipment, however, do not share this view.

In general, it is well accepted that expo-

sure limit comparisons should be based

on the maximum value emitted from the

direction of the strongest radiation sour-

ce.

When a 2.4-GHz telephone inside the house,

for instance, emits a similar level of microwa-

ves as a nearby cellular phone base station

outside the house, it could be helpful to first

turn off the 2.4-GHz telephone inside the

house to measure the exposure level origina-

ting from the outside. After also having mea-

sured the emission of the 2.4-GHz telephone

on its own, the sum of both measurement

values could be used for the exposure as-

sessment. Right now we have no clearly de-

fined testing protocol because according to

national standard-setting institutions - as

described earlier – quantitatively reliable, tar-

geted and reproducible measurements are

only possible under „free field conditions“

but not in indoor environments.

To be on the safe side, the RF exposure

comparison should be based on a value deri-

ved from multiplying the display value by the

factor 4.

This correction factor may appear extremely high

at first sight. As soon as put into perspective of professional

spectrum analyzers, which already use a factor of 2, however,

the relative nature of this factor becomes obvious.

Regardless of the measurement uncertainty

technically inherent to the RF analyzer, for

measuring cellular phone base stations it is

recommended that a factor of up to 4 is put

on the displayed measurement value in order

to take into account the potential maximum

power density at full usage of the network in

contrast to the minimum power density. The

minimum RF level occurs when only the con-

trol channel operates, whose signal strength

is unaffected by the number of phone calls

being placed at any given time. In order to

obtain the most realistic minimum value for

calculating the maximum exposure, it is sug-

gested to take measurements at different

times during the day, especially at known

low-traffic times such as Sunday morning or

the like.

Hint for Cellular Phone Users:

Cellular phone reception is still possible well below the strict exposure limits of the

Building Biology Guidelines for pulse-modulated RF radiation, that is power density

levels below 0.1µW/m² or 0.01 nW/cm², respectively.