Ham Radio General Class Test 2025 – 400 Free Practice Questions to Pass the Exam

Impedance mismatch in an antenna system occurs primarily due to the difference in impedance between the antenna and the feed line. Each component in the transmission line, including the antenna and the feed line, has a characteristic impedance. When these impedances do not match, reflected power can occur, which leads to loss of efficiency and can affect the performance of the antenna system.

The ideal scenario is where the impedance of the antenna (often 50 ohms for many systems) matches that of the feed line, which allows maximum power transfer from the transmitter to the antenna. When there is a mismatch, part of the power transmitted is reflected back toward the transmitter rather than being radiated as desired.

While the quality of the feed line and its length can affect overall performance, they are not the primary cause of the mismatch itself. Quality issues can introduce losses, and length can affect the phase relationship over certain frequencies, but the crucial factor remains the inherent impedance difference. Similarly, the power output of the transmitter does not influence the impedance characteristics, though it may dictate how much power could potentially be lost due to a mismatch.