Balloon-supported verticals
Experiments with 136 kHz vertical antennas, from house-mounted prototypes to balloon-supported wire extensions for LF DX.
Description
GW4ALG's 136 kHz Pages document the evolution of vertical antennas for the 2200m band, starting with a prototype mounted on a house wall. This initial design, despite achieving the first 395 km GM-GW QSO, suffered from significant insulation breakdown, high RF losses due to proximity to the house, and difficult tuning adjustments. The author details the challenges of maintaining resonance and matching with a variometer in the loft, noting that adding three earth spikes offered no measurable improvement over a simple water tap connection.
The subsequent experimental 12m vertical, relocated away from the house, significantly reduced dielectric losses and proved far more effective. This antenna enabled GW4ALG to set a world DX record on 136 kHz with a 1916 km QSO to OH1TN, and an intra-UK record of 703 km to GM3YXM/P. The resource further explores the use of helium-filled balloons to extend the vertical radiator, achieving heights up to 27m, typically 20m, for enhanced low-band performance. Practical advice on balloon types, inflation, and critical insulation between the wire and balloon is provided, emphasizing safety and avoiding arcing.