Most modern analyzers used today to characterize the antenna system use the Frequency
Domain Reflectometry (FDR) technology. This technology uses RF frequencies to analyze
the data, providing the ability to locate changes and degradations at the frequency of
operation. Analyzing the data in the frequency domain enable users to find small degradations
or changes in the system and thus can prevent severe system failures. Another major benefit
of analyzing the system using RF sweeps is that antennas are tested at their correct operating
frequency and the signal will go through frequency selective devices such as filters, quarterwave lightning arrestors, or duplexers which are common to cellular antenna systems.