33Nardalert S3 Narda
6.2 Verication overview
• Higher microwave frequencies (>2 GHz) are primarily detected with
thermocouple arrays. This detector is a true “square-law” sensor that
will always yield RMS average results, even in a pulse-modulated expo-
sure environment.
• Individual outputs from all three detectors are processed by the NS3
with their calibration information supplied by the sensor’s imbedded
EEPROM. All units are individually calibrated to facilitate eld support.
The NS3’s design utilizes RF shielding and absorbers to isolate it from
reections or scattering produced by the monitor, or the human body.
In general, the monitor cannot detect microwave elds from behind the
body when it is worn on the front of the body. At low frequencies (<100
MHz), however, the body can act as an antenna and introduce energy into
the monitor, even when the source is from behind the wearer.
Testing RF/microwave sensors
The NS3 includes a menu screen (Sensor Test) that allows users to generate
their own signal to see the monitor respond. Note that your signal’s power
and frequency need to be sucient to register a response on the monitor.
North American users may nd that a common “family radio” operating at
433 MHz and at least 2 Watts of power can be used as a simple, but eec-
tive test source.
Required equipment for testing RF/microwave sensors
Standard “elds” need to be established with relatively high RF powers
required (>10 Watts). The NS3 is factory tested inside of a “TEM” cell at
frequencies below 300 MHz, and then positioned in front of standard gain
horns from 300 MHz to 50 GHz. Special arrangements are made by Narda
to test frequencies above 50 GHz. Refer to IEEE 1309 Standard for eld
generation methods.
This document is not intended to train the reader in the art of generating or
verifying the elds used to excite the NS3. Readers are cautioned to review
or familiarize themselves with the various international standards setting
groups that oer guidance in this engineering discipline.
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