Tree Antennas

As part of the recent simulated Catastrophic Disaster, members of the Australia's Maryborough Electronics & Radio Group, 'MERGE', gathered with the usual collection of bits and pieces which could conceivably be lying around after such a disaster.

They had, on previous exercises, exhausted the more common HF antenna designs, so Van, VK4VAN, suggested that they try to utilise a tree as the radiating element.

This idea was part of a British patent in 1917, but it was not useable as it involved driving a spike into a tree in the park, totally against Council regulations.
http://www.rexresearch.com/squier/squier.htm

An article by W5JGV, about a toroidal feed to a tree antenna on the 40m band, seemed more useful.
http://w5jgv.com/tree_antenna/index.htm

Among Ray, VK4TPT’s, collection of antenna documents were both articles in printed form, so a length of flexible water pipe was quickly converted into a coil and wrapped as a yoke around a nearby Gum tree.

Conveniently, there was a water tap at the base of the tree and one end of the coil was connected to it as an earth.

From VK4TPT’s box of bits came an old tuning capacitor which was connected in series between the other end of the coil and the antenna socket of Ray’s trusty TS-520S.

A little adjusting of the coil and capacitor soon caused a solid noise signal from the 520S and a quick tune across 40m brought in signals from VK2, 3, 5 and 7.

Further adjustments produced a useable match and a 4/1 contact was made with VK2JE, Brian, who was MOBILE near Tuncurry, NSW.

This was followed by a 5/6 contact with Seth, VK2CJA in Coffs Harbour, and several 5/9+ contacts locally.

Ray and Van would have liked to try other bands, but the BBQ, in conjunction with the Woocoo SES, was under way, and the lads were just a little hungry.

It’s obvious that tree antennas do work, but the big question now is: What will 'MERGE' try next year?

Wireless Institute of Australia