ETS-Lindgren HI-3510 RF Radiation Badge Broadband Electromagnetic Radiation Detector (Archived) - Manual (Page 20)

HI n 3510 Manual Page — 15
SECTION IV
THEORY OF OPERATION
4.1 GENERAL
The Model HI-3510 is a portable, battery operated, non-
ionizing radiation hazard detector intended for personal
use. It detects electromagnetic radiation from RF and
microwave sources in the frequency range from 0.05 to
2.5 GHz and alerts the user to potentially hazardous
fields. The Model HI-3510 enables the user to set the
alarm warning level anywhere in the range from 0.2 to 20
mW/cm 2 . In addition, the user can choose either of two
measurement modes: instantaneous exposure level or a
six minute average measurement. Both modes are
displayed on a three digit LCD panel along with a ten
segment bar graph normalized to the selected alarm
warning level.
4.2 MAGNETIC FIELD SENSOR
The Model HI-3510 uses an isotropic array of tandem
loops, each feeding a Schottky diode detector. The
outputs of these loops are summed to a common feed
line. Utilizing a unique cancellation scheme, the resulting
rectified voltage represents only the magnetic field
component. The electric field component is canceled out
and does not appear in the measurement. The diodes are
operated in their low level region to assure square law
performance.
4-3 DC CIRCUIT
The DC output produced by the RF circuit is amplified by
a differential chopper-stabilized amplifier. This circuit has
Archived 4/2/10