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8.5 Building Attenuation
at UHF, L- and S-Band Via Earth-Satellite Measurements
In this section are described building attenuation measurements at 860
MHz, 1550 MHz, and 2569 MHz using the Application Technology Satellite
No. 6 (ATS-6) as the radiating platform [Wells,
1977]. Transmissions at each of the frequencies were right-hand circularly
polarized and the receiving antenna was a vertically polarized azimuthally
omni-directional conical monopole located above a short ground plane. Measurements
were made on several wood-frame siding houses and several wood frame brick-veneer
houses in five geographic locations. The elevation angles at these location
were 36.1° (Duluth, MN), 42.3° (Boulder, CO), 44.7° (Kansas
City, MO), 49.6° (Little Rock, AK), and 55.4° (Houston, TX). A
series of measurements were made at different locations within each house
(e.g., 16) and related to measurements made outside the house to obtain
the relative attenuation. The average attenuation and standard deviation
for each house were subsequently determined.
8.5.1 Experimental Results
Wells emphasizes in his results: (1) two building types; wood siding and
brick veneer, (2) two insulation types; ceiling, and ceiling and walls,
and (3) two room exposure types; one or more exposed walls and no exposed
walls. An exposed wall implied that the line-of-sight path passed through
a single wall, whereas an unexposed wall scenario implied that the wall
was sheltered by another room or another wall. A four factor model including
frequency (4 levels), construction type (2 levels), insulation type (2
levels), and room position (2 levels) was developed and summarized by the
listing in Table 8-17.
To obtain the overall attenuation for a particular structure employing
Table 8-17, we execute the following example
steps: (1) The "Average Value" of 6.3 dB is added to values described in
subsequent steps. (2) For a frequency of 2.569 GHz, we add +1.16 dB to
the average value. (3) For a brick veneer construction, we add +0.58 dB.
(4) For a structure with insulation in both ceiling and walls, add +0.8
dB, and (5) for a room with unexposed walls, add +0.30 dB. The overall
attenuation is 9.14 dB for the above combination of effects. Wells culls
out several "high attenuation" structures. These are two mobile homes (average
attenuation of 23.6 dB) and two wood frame houses with interior walls and
ceiling comprised of plasterboard backed with aluminum foil (average attenuation
of 17.1 dB). Wells also shows that no significant attenuation occurs as
a function of elevation angle.
Wells summarized the above results as follows: (1) On average, the signal
level varied by 0.6 dB as a function of position of a room within each
house. (2) Houses having brick veneer gave rise to a 1.2 dB higher attenuation
than houses with wood siding. (3) Insulation in ceiling and walls caused
about 1.6 dB higher attenuation than insulation in ceiling only. (4) Insulation
and plasterboard with aluminum backing caused attenuations between 14.6
to 22 dB. (5) The attenuation at 2.569 GHz was approximately 2.9 dB larger
than at 860 MHz. (6) Horizontal polarization at 860 MHz gave approximately
1.8 dB higher attenuation than vertical polarization.
Table 8-17: Average attenuation contributions
at UHF, L, and S-Band [Wells, 1977].
|
Parameter
|
Characteristic
|
Attenuation Contribution (dB)
|
|
Frequency
|
2.569 GHz
|
1.16
|
|
|
1.550 GHz
|
0.39
|
|
|
0.860 GHz (V)
|
-1.69
|
|
|
860 GHz (H)
|
0.14
|
|
Construction
|
Wood Siding
|
-0.58
|
|
|
Brick Veneer
|
0.58
|
|
Insulation
|
Blown-In Ceiling
|
-0.80
|
|
|
Ceiling and Walls
|
0.80
|
|
Room Position
|
Exposed Walls
|
-0.30
|
|
|
No Exposed Walls
|
0.30
|
|
Overall Average
|
6.3 dB
|
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