78 Chapter 6
Characterizing and Verifying Antenna Systems
Antenna Feedline System
Evaluating the quality of the components within the antenna feedline system is of
utmost importance in today's communication systems. For example, the attenuation
of the transmission lines, along with the insertion loss of the combiner, determines
the majority of loss that occurs in the transmitting portion of the antenna system.
Any imperfections or damage to this feedline can severely impact the transmission
quality of the entire system.
Figure 6-2 Antenna Feedline System
The antenna system assembly consists of:
• main feedline and jumper cables (coaxial or waveguide)
• connectors or flanges
•hangers
• antenna
It is important to understand the effect the feedline assembly has on the entire
system to help avoid intermittent problems and failures.
Knowing performance parameters such as feedline loss is especially critical when
operating in the 800 to 900 MHz and 1.8 to 2.0 GHz frequency ranges. At these
frequencies, the wavelength is very short and suffers greater propagation attenuation
than the longer wavelength signals of lower frequencies. Thus, the system
performance, in terms of the power transferred from the transmitter to the antenna,
and from the antenna to the receiver, is characterized by the antenna feedline.
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