Page 115 - Antennas for Base Stations in Wireless Communications

88 Chapter Two

(a) (b)
Figure 2.20 (a) Space diversity and (b) polarization diversity high-band antenna
systems mounted on monopoles typically 15-m high (Photos by the author)

a street lighting column. In this second case, the cabinet housing the
base station equipment is no more conspicuous that the control box for
the traffic light (lower right). Urban sites can usually be connected by
underground data lines so there is no requirement for a rigid structure
to support a narrow-beam microwave antenna.
Base station antennas have successfully been integrated into advertis-
ing signs and their incorporation in a functional flagpole can allow them
to be erected with little controversy in many locations where a utilitar-
ian engineering design would be completely unacceptable. Disguise is
also possible using dielectric panels that simulate building features.
Simple measures like avoiding the projection of antennas above the
roof line are very effective—of course, this impacts radio planning, but
there are many instances in which this impact can be accommodated.
In rural areas, measures such as avoiding placing structures on the
skyline, choosing sites near the edge of woodland, or simply painting
structures in harmonious colors can limit the impact of base stations.
The use of artificial “trees” is well known; although unsympathetic and
obtrusive examples can be seen in some locations, the most successful
examples are probably simulated coniferous trees located close to conif-
erous woodlands.