Ham Radio General Class Practice Test

What characteristic of an antenna is typically evaluated using an antenna analyzer?

1. Bandwidth

2. Directivity

3. Reflection coefficient

4. Radiation pattern

The correct answer is: Reflection coefficient

The reflection coefficient is a critical parameter examined when using an antenna analyzer. This value describes how much of the radio signal is reflected back by the antenna rather than being transmitted or received as intended. It is an important characteristic for assessing the efficiency of an antenna. A strong reflection coefficient suggests that the antenna is not properly matched to the transmission line or the frequency of operation, indicating potential issues in performance. In practical terms, an antenna analyzer measures the impedance at the antenna feed point and calculates the reflection coefficient, often expressed in terms of Voltage Standing Wave Ratio (VSWR). A low reflection coefficient or VSWR indicates that the majority of the power is being effectively transmitted or received, which is desirable for optimal antenna performance. Other characteristics like bandwidth, directivity, and radiation pattern can also be evaluated with different tools and through various methodologies but are generally beyond the primary function of an antenna analyzer, which focuses on the relationship between impedance, frequency, and the efficiency of power transfer.