Short Multiband Dipole Array
Build a compact, multi-band HF dipole array with loading coils for limited space.
Description
A 60-foot available space, for example, might necessitate a shortened multiband dipole array to cover 80, 40, and 15 meters effectively. This resource details the construction of such an antenna, combining full-size and coil-loaded dipoles on a single feedline. It addresses the common challenge of fitting multiple HF bands into restricted physical footprints, providing practical guidance for hams with smaller backyards or portable operations.
The core of the offering is an interactive calculator that determines required loading coil inductance and dipole lengths for various amateur bands from 160m to 10m. Users input their available space, and the tool provides dimensions, coil turns, and an efficiency rating (Good or Fair) based on the antenna's electrical length relative to a quarter-wavelength. It also suggests suitable PVC pipe diameters for coil forms.
The article further illustrates a center feed-point assembly using an 18-inch section of 2-inch PVC pipe, detailing eye-bolt spacing and coaxial connector installation. It emphasizes the importance of adequate spacing between parallel dipoles and offers customization options for the feed-point, including the addition of a Balun for improved feedline isolation.