Handbook of Propagation Effects for Vehicular and ... - Courses

8-30
Propagation Effects for Vehicular and Personal Mobile Satellite Systems
(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 lineof-sight
path passed through a single wall, whereas an unexposed wall scenario implied
that another room or another wall sheltered the 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 from 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. (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.