An HF Mobile Antenna

Constructing a mobile HF antenna presents unique challenges, particularly when aiming for multiband operation and robust mechanical stability. This project details N1GY's adaptation of the KM4IE $20 antenna and the Texas Bugcatcher design, focusing on practical build considerations and on-the-road performance. The author shares insights from winding coils on 2-inch PVC forms and integrating a salvaged fiberglass core from an old Hamstick-style antenna to enhance structural integrity, preventing potential failures from stress on PVC joints.

N1GY's build includes a custom matching coil and a commercially sourced MFJ loading coil, carefully integrated into the design. The article provides specific tap settings for bands from 75 meters to 15 meters, achieving SWRs as low as 1.2:1 on 40 meters and 1.6:1 on 75 meters. Mechanical testing involved driving at speeds up to 70 MPH on Interstate routes, confirming the antenna's durability and the effectiveness of its PVC brace system.

Further modifications address real-world usability, such as simplifying antenna removal for car washes. The ground strap was updated with a Power Pole connector, and the brace attachment to the luggage rack was converted to wing nuts, reducing removal time from 30 minutes to approximately five minutes. This iterative design process highlights practical solutions for mobile HF operation.