Page 86 - Integrated Wireless Propagation Models

64 C h a p t e r T w o

Region Excess Propagation Loss Limits
Line-of-sight fMHz < 16
16 � f H z � 20
M
fMHz > 20

A R EF = -20 log ( I E5FW/E01)
AsELoss from Table 3- 1
Diffracting AD/F,HF = ASELOSS fMHz � 16
AD/F,a = cxAD/F, H F + (1 - a AD/F.VHF 16 < f M z
)
H � 20
K ;::: 3 and Akf � 7 d B
{ min (A sELoss. AKN/FE )
AD/F,V H F - _ 2 0
A KNIFE fMHz >
K < 3 or k 7 d B
A E >
fMHz > 2 0
A5ELoss from Table 3- 1
_
a = 1,4 f M Hz + 5
AKN/FE = -20 log ( I E 01 F/E01)
- 1 �
k
AkE = k £-AF ,
a
1,/REM: Total terrain-dependent propagation loss for LOS n d BLOS path
LFS: Free space loss
ALOS: Excess loss for LOS as determined by the frequency
A ABSORB: Molecular absorption loss
ADIF: Excess loss for the diffraction region
L,RO: Troposcatter loss
d
ASELOSS: Spherical-earth loss due to the contribution from surface wave and i ffracted wave,
depending on the relative permittivity and conductivity of the terrain
Loss relative to free space due to the reflected ray
= 5 - fMH,/ 4
E spW: I n tensity of space wave
Eo: I n tensity of direct wave
ADIF,HF: Diffraction loss (estimated by the spherical earth) for frequency less than 16 M H z
i
AOIF,a : Loss for the n termediate frequency region 16 < fMHz � 20
M
AOIF,VHF: Diffraction loss for 20 H z and above
d
A KNIFE: Knife-edge i ffraction loss above free space
i
�IF: K knife-edge field n tensity
AkE: Average knife-edge loss value, if more than two knife edges
K: Number of knife edges
Magnitude of the Fresnel n tegral for each knife edge
i
= -20 log Fk
TABLE 2.7.2.1 Summary of Terrai n -Dependent Propagation Formulas for LOS or Diffraction