Using PMM RA-01
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3 – Using PMM RA-01
3.1 How it works
PMM RA-01 is an active, high sensitivity Electric field receiving antenna. It
has a built in preamplifier. It works as a short monopole over a ground
plane. Its intrinsically high impedance within the covered frequency band is
transformed and normalized by the internal preamplifier.
3.2 Power switch
To turn the unit on and off push the black switch located on the side panel
of the box.
3.3 Battery charging
When the unit is on, the light from the green led placed inside the power
switch indicates the remaining charge of the internal battery. So the light
becomes weak when the battery voltage goes down. In this case the
battery needs to be recharged. To charge the internal battery: switch the
unit off, then plug the supplied AC battery charger in the supply mains and
connect the apposite connector to the ROD box.
In order to safeguard the features of the batteries, it is recommended
to fully recharge it before using the antenna.
Do not charger for more than 6 hours.
It is warmly suggested to recharge the batteries at least every 4
months even though the device has not been used.
3.4 ESD risks
Since the monopole terminal is directly connected to the high
sensitive preamplifier, built using a delicate Field Effect Transistor, it
is important not to touch it before proper grounding and being sure
to avoid ESD effects.
The static charge carried by test personnel can damage the FET.
3.5 Principles of
operation
The most important assumption to be done concerns the length of the
monopole. If it is short enough, and it means less then 1/8 wavelength at
the higher frequency of the covered band, the current distribution over the
antenna can be approximated to be linear.
The 1m length makes easy to calculate the field strength that is usually
measured as Volts per meter. It is only necessary to take in count of the
effective length of the antenna that is a half of its physical length. This
means that a +6dB must be added to antenna factor when electric field
strength is measured. In the meantime this length corresponds to a 1/8
wavelength at the frequency of about 37MHz, so it is possible to use it up
to more then 30MHz. The ideal situation to use a rod antenna is when it
operates in reference to an infinite ground plane. The small box containing
the preamplifier should be connected to the real ground. If the case is not
well grounded important reading differences can appear.
The RA-01-HV model is protected from low-frequency disturbance signals
by internal 150 kHz High Pass Filter (for example: Main Power 50/60 Hz)
If radiated by electromagnetic fields higher than 5kV/m 50/60 Hz, the
antenna can be damaged
Please do not touch the Display of 9010F while using RA-01, in order
to prevent measured E-field from being affected by wrong
contribution through human body radiation
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Document RA01EN-71011 -
NARDA 2017
