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The frequency range of the HFW35C comprises the frequencies of lower and upper WLAN-bands, Bluetooth, some Radar- and beam-radio-frequencies as well as both of the WiMAX-bands.
Control elements and Quick Start Guide
Connecting socket for antenna cable. The antenna is inserted into the “cross like” opening at the front tip of the instrument.
Important: Do not bend the cable too sharply or overtighten the connector screw!
„Power“ On/Off
switch
( = ”Off“ )
„Signal“ For building biological assessment use „peak“.
„Range“
Set the sensitivity according to the level of radiation .
“Full” / “Pulse” for choosing the whole signal to be displayed or only the pulsed fraction
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Attenuator knob for audio analysis of digital HF services
(HF35C and HF38B only; the HF32D has a “Geiger counter” effect proportional to the signal)
The meter includes an
Auto-Power-Off-feature.
When the “
Low Batt“ indicator appears in the centre of the display, measurement values are not reliable anymore. In this case the battery needs to be changed. If there is nothing displayed at all upon switching the analyzer on, check the connections of the battery or change battery. (See „Changing the Battery“)
Introduction to Properties of HF Radiation and
Consequences for their Measurement
Permeation of many materials
In particular for measurements inside of buildings it is important to know that construction materials are permeable for HF radiation to a varying degree. Some part of the radiation will also be reflected or absorbed. Wood, drywall, and wooden window frames, for example, are usually rather transparent spots in a house. More information can be found on our website.
Polarisation
Most High Frequency radiation (“waves“) is vertically or horizontally polarised. With the antenna attached the meter measures the vertically polarised component, if the display is positioned horizontally. By rotating the meter around its longitudinal axis you will be able to pick up any polarisation plane.
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More specific: the amplidude-modulated fraction
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Fluctuations with regard to space and time
Reflexions can cause highly localised amplifications or cancellations of the high frequency radiation, in particular inside buildings.
This is why one should stick to the step-by-step procedure in the next chapter.
In addition, most transmitters and cellular phones emit with considerably varying power during a given day and in the long term, depending on local reception and load. Therefore repeat measurements at different times of the day on working days and at weekends. In addition it may be advisable to repeat them occasionally over the year, as the situation can change over night. As an example, a transmitter only needs to be tilted down by a few degrees in order to cause major changes in exposure levels (e.g. during installation or repair of cellular phone base stations). Most of all it is the enormous speed with which the cellular phone network expands every day that causes changes in the exposure levels.
The nature of HF radiation requires a specific approach for each
- the determination of the total exposure to it and
- the identification of the sources or leaks for the pollution.
Step-by-Step Procedure to Measure the
Total Exposure
When testing for HF exposure levels in an apartment, home or property, it is always recommended to
record individual measurements on a
data sheet. Later this will allow you to get a better idea of the complete situation.
Connecting the Antenna
Screw the angle SMA-connector of the antenna connection into the uppermost right socket of the HF analyzer. It is sufficient to tighten the connection with the tightening aid. Do not use a wrench or other tools because over tightening may damage the threads.
The radiation in the frequency rang of this instrument are normally vertically polarized. An orientation of the antenna suitable for this is as shown in the following picture:
Do not twist the antenna cable or bend it sharply!
For horizontal orientation of the antenna you should rotate the
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Made in Germany instrument rather than twisting the cable. The LED at the front of the antenna indicates a good connection, which is essential for an accurate measurement!
Remarks concerning the antenna
The “semi rigid” cable has the best technical parameters in the instrument’s frequency range. It is designed for several hundred changes of orientation without effects for the accuracy of the measurement. For the special design of the second connecting cable we have a patent pending. The objective is to reduce an inherent weakness of “simple-log.per” antenna designs made of PCB material. For radiation incoming at an angle to the main direction normal designs pick up signals also below the design frequency range, which can falsify the measurement. This antenna suppresses this by 15 to 20 dB in addition to the approx.
40 dB of the high pass filter.
Settings of the Analyser
At first set
”Range“ to ”1999
µW/m²“. Only if there are constantly very small readings, switch to the finer range.
The basic rule is:
as coarse as necessary, as fine as possible. In the rare case of power densities beyond the designed range of the analyser (“1“ displayed on the left hand side even in the coarsest range) they can still be measured by inserting the attenuator DG20_G10, available as an optional accessory, which makes the instrument less sensitive (by a factor of 100).
Setting Signal Evaluation (“Signal“): The peak HF radiation val-
ue, not the average value, is regarded as the measurement of critical “biological effects“ affecting the organism and to be compared to recommended safety limits.
The
average value (“RMS“) of pulsed signals is often only a very small fraction of the peak value. Nontheless it forms the basis of most of the ”official“ safety limits regulations. Building biologists consider this a trivialization.
How to execute the measurements
Hold the HF analyzer with a slightly outstretched arm, your hand at the rear of the instrument.
For a rough
first overview it is sufficient to probe for areas of higher levels of radiation simply by following the audio signals walking through the rooms of interest, directing the analyser everywhere and rotating it.
Having identified the area of interest for a closer evaluation, change the positioning of the instrument in order to analyse the actual power flux density. This is done
- by
pointing in all directions including upwards and downwards in flats to establish the main direction of the incoming radiation,
- by rotating the instrument around its longitudinal axis by up to 90
°
to also find the plane of polarisation, and
- by shifting the instrument in order to find the point of maximum exposure and to avoid being trapped by local cancellation effects.
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