HF mobile antenna

The HB9ABX mobile HF antenna, developed by Felix Meyer, offers a high-performance alternative to commercial mobile antennas for 80 through 10 meters. Constructed from fiberglass rods and enamelled copper wire, this design incorporates a loading coil with multiple taps, allowing for band-specific tuning. The article provides detailed instructions for winding the coil, connecting the antenna elements, and integrating it with a vehicle's chassis ground.

Field tests conducted at 100W consistently showed the HB9ABX antenna outperforming a HUSTLER mobile antenna by up to 10 dB (1 S-point) and a YAESU ATAS-100/120 by 18 dB (2-4 S-points) across distances from 5 km to 1000 km. The design emphasizes a robust ground connection and the use of an antenna tuner, such as an MFJ-901B, for optimal SWR on all bands, particularly 40 and 80 meters. Initial adjustment involves setting whip length and coil tap positions to achieve resonance without a tuner, followed by fine-tuning with the tuner during operation.

Specific measurements are provided for checking resonance on 21.0 MHz and 14.2 MHz, with precise turn counts for the lower (79 turns) and upper (120 turns) antenna sections. Safety precautions for handling fiberglass dust are also highlighted.