GEM80-400 1. Introduction
Issue 3 04/99 ALSPA GEM80-400 CONTROLLER TECHNICAL MANUAL Page 1-25
1.13.7. Transmitter Output
The field strength generated by a radio transmitter, received at a point 'p' in
free space, is a function of the power output of the transmitter and the
distance from the transmitter aerial.
E = √√ { (377Pt) / (4ππr
2
) } or
r = (5.5 / E) √√ Pt
where E = Field strength at point 'p', in Volts per metre (V/m).
Pt = Power output of the transmitter, in Watts.
r = Distance of point 'p' from the transmitter, in metres.
Note...At two metres, the power required to give a field strength of 10V/m is 13
Watts.
The following assumptions have been made in the formula above:
The antenna gain is unity.
The antenna is isotropic.
The transmitter and the products are in free space.
Far field conditions exist, where the wave impedance is 377Ω.
In the near field, both the electric and the magnetic
components of the field must be considered.
Calculations based on the formula above which result in distances less than
two metres are incorrect.
1.14. Handling Precautions for Printed Circuit Boards
1.14.2. Introduction
A number of microelectronic devices on equipment PCBs (printed circuit
boards) are subject to permanent damage due to static (electrostatic
potentials) encountered in routine handling, testing and shipping, unless
special precautions are observed. For example, static electricity can be
generated simply by an operator moving on a chair, brushing against benches
or walls, or walking across the floor, and so, appropriate action must be taken
to discharge this 'personal static' when handling individual PCBs. Once the
PCBs are plugged into a subrack they are protected from any static damage.
This section details action for the protection of PCBs from static damage.
1.14.3. Protection of Equipment from Static Damage
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