5.3 Without Line-of-Sight

 

 

 

 

When line-of-sight is not possible, signal penetrates and is reflected by different

 

objects to reach the destination. Therefore, it is important to learn about how

 

these materials would affect signal propagation.

 

 

 

 

Depending on the thickness, moisture content and angle of incidence, a wall

 

may allow between 1% and 25% of the radio power to pass through.

 

Metal panel or metalized glass window will not allow much radio power to pass

 

through. Signal will be reflected if the panel is a mirror.

 

 

 

 

Some radio power may propagate through small holes in the panel or around

 

metal edges through the process of diffraction.

 

 

 

 

Material Type

 

Possible Signal

 

 

 

 

 

 

Wood, Plaster, Sheetrock, Fiberglass

 

Reduction

 

 

 

0 to 10%

 

 

Uncoated Glass w/out Metal

 

 

 

Brick, Pressboard

 

5 to 35%

 

 

Reinforced Concrete

 

10 to 90%

 

 

Metal Walls, Metal Doors, Elevators, Metal Piping,

 

90 to 100%

 

 

Metal Stair Cases, Metal Mesh, Metal Screening

 

 

Figure 5.3 Materials in Buildings

In a non-line-of-sight situation at 2.45 GHz, it is possible to move the receive antenna only 1 to 1 1/2" (3 to 4 cm) and see signal strength varies from

6 dB to -20 dB due to multiple signal reflection path. Therefore, there should be about 20 dB path loss margin to take signal fading into account.

5.4Casing and Closure Around the Antenna

See Section 2.1.4.2 and Figure 2.5.

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Image 76
Omega WI8XX-U manual Without Line-of-Sight, Casing and Closure Around the Antenna, Material Type, See .1.4.2 and Figure