CP480 Wireless Communication and Networks

Attenuation of Building Materials

Objectives

1. To examine how wireless power is affected inside buildings systems.

Equipment

• wireless power meter

Procedure

For each of the following measurements, be sure to repeat each measurement enough times to produce a reasonable average and uncertainty.

1. Measure the power in the hallway, and then inside the lab (i.e. on the other side of the brick wall) to see how much the signal is attenuated by the wall.
Try to do it so that the wall is perpendicular to the direction of the radio waves.
Try to do it so that the distance from the source is the same.

2. Figure out how to measure the signal on both sides of a door, to determine the attenuation of a door.

3. A Faraday cage is a space surrounded by a metal cage to eliminate radio interference from traveling in or out. One of our labs, N2089, was constructed as a Faraday cage so that experiments with high voltage discharges in that lab would not produce interference in other labs.
Measure the signal just outside and just inside N2089 to determine how effective the Faraday cage is. As before, try to do it so that the wall is perpendicular to the direction of the radio waves, and the distance is unchanged.
We actually have two labs designed as Faraday cages. Can you figure out which the other one is? Hint: What is visually different about N2089?

4. Look for evidence of each of the following phenomena (Note: You may not see some of them.):
(In your lab notebook, note how you did each one.)
• Reflection:
Can you see an increase in signal near a reflective surface?
Can you see fluctuations in signal over a distance of 1/2 wavelength?
• Diffraction:
Can you see the signal bending around corners?

Before you leave the lab, have the lab instructor sign your lab notebook immediately after your last entry.

Resources

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