2-GHz microwave systems typically use coaxial cable as
the transmission line between the radio equipment and
the antenna (see Figure 3). Because of attenuation
considerations, elliptical waveguide is nearly always the
transmission line of choice for 6.5-GHz systems (see
Figure 4). For this reason, it will be necessary to replace
the coaxial line with elliptical waveguide.
You should consider three factors when replacing the
transmission lines:
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Transmission Line Attenuation. For system path recal-
culation, you should consider the difference in signal
attenuation between the existing coaxial line and the
new elliptical waveguide.
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Transmission Line Tower Support. The hanger sys-
tems used to attach and support coaxial cables and
elliptical waveguides to the tower are different in
shape and size. Reconfiguration of the hanger system
will be required when the system is migrated to 6.5
GHz.
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Pressurization/Dehydrator System. If your 2-GHz
system uses foam-filled, unpressurized coaxial
transmission line, you probably do not have a pres-
surization/dehydrator system in place. Your new 6.5-
GHz system, however, uses elliptical waveguide,
which requires pressurization and a dehydrator system
will have to be installed at each site.
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Figure 3 - 1850 to 990 MHz Systems.
HELIAX Coaxial Cables
Figure 4 - 6525 to 6875 MHz Systems.
HELIAX Elliptical Waveguide, Types EW63
and EWP63
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