A light weight compact Doublet Antenna

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.

Doublet in action

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.

Feed Line

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.

2m of 3mm cord is attached to each end

The Em Tech ZM-2 provides a low vswr on all bands tested (80 -10m).

Packed up

Using the figure 8 winding technique the antenna fits onto one of my core flute winders for transport. Packed weight ~135 grams.

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