Collapsible 6-meter Beam Antenna - Design and Performance
Description
This document details the design and on-air results of a collapsible 6-meter beam antenna, inspired by foldable dipole concepts and similar wire beam constructions like the Penn. State 40m beam and DJ4SA Spiderbeam. The presentation covers the geometry of the 4NEC2 model, predicted VSWR, gain, and front-to-back ratios. Modeling observations discuss optimizing element lengths for gain and bandwidth, and the impact of end loops on resonant frequency. A key section addresses feeding the aprox 25 ohm impedance balanced antenna using 50 ohm unbalanced cable, explaining a feed network incorporating a choke balun and a matching network utilizing two series quarter-wave transformers with 75 ohm cable. On-the-air results include a 1st double hop Es QSO with 10 Watts, a 1st QSO on Field Day with 5 Watts, and satisfactory performance in the CW WW VHF Contest from FN05, working 41 grids with 100 Watts, noting improved performance over a dipole.