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

Chapter 6
Polarization, Antenna Gain and Diversity
Considerations
6.1 Background
This chapter reviews a number of L-Band and UHF propagation effects associated with
land-mobile propagation scenarios. These include fading effects related to:
(1) depolarization, (2) antenna gain, (3) lane changing, (4) antenna space diversity, and
(5) satellite diversity. A number of the effects examined were derived from
measurements by Vogel et al. [1992], Akturan and Vogel [1997], Vogel [1997],
Goldhirsh and Vogel [1987; 1989], and Ryuko and Saruwatari [1991].
6.2 Depolarization Effects
By making repeated measurements with co- and cross-polarization at 1.5 GHz for
selected runs (elevation = 51°) during an Australian campaign, equi-probability “crosspolar
isolation levels, CPI” were determined by Vogel et al. [1992]. The cross
polarization isolation is defined as
COPS(
P)
CPI ( P)
= , (6-1)
CRPS(
P)
where COPS(P) and CRPS(P) represent the co-polarization and cross-polarization signal
levels at the equi-probability value P. The CPI (in dB) is plotted in Figure 6-1 and was
found to follow the linear relation
CPI = −1
. 605A
+ 18.
94 , (6-2)
where A is the co-polarized fade (in dB) with a range between 0 and 11.8 dB.