To overcome some of the complexities of counterpoise length and ground type when using a random end-fed wire in the field I have revisited the doublet antenna. The key criteria was to make an antenna that is as easy to pack and transport as the simple end-fed wire.
An old dos antenna program was used to provide the expected impedance at the matching unit, this and some testing in the backyard finished up with a top of 13.8m end to end and feeder length 5.5m. Feeder length was also effected by my desire to fit my 4.9m squid pole.
Wire re-purposed from a 15m Cat5 patch cable. Center insulator is a piece of 3mm plastic sheet cut out using a 40mm hole saw.
Spacers are Drip Water system risers cut to 25mm. Wire is held in place with nylon line and a small dab of liquid electrical tape to insure the knot does not come undone. Spacers do slide a little on the feed line but with about 150mm spacing there are plenty to keep the line in shape.
The Em Tech ZM-2 provides a low vswr on all bands tested (80 -10m).
Using the figure 8 winding technique the antenna fits onto one of my core flute winders for transport. Packed weight ~135 grams.
