A 40m Bruce Array for WI-001L Operations 23 - January - 2007Posted by k9zw in Amateur Radio, K9ZW Built.
I’ve been long interested in Wire Curtain Antennas, from when I first saw large arrays used by organizations like Radio Free Europe, Voice of America, Government Agencies that I’m going to let you Google on your own, rather point links from this blog at them, and Military Units, onwards.
A recent hiking trip happened by the VLF communications site at Anthon Cumbria again peaking interest in large wire arrays.
When W9EVT mentioned that his 40m Bruce Array had been lost to farm vehicle damage while down for service, I found my chance to have a first hand effort at building a small wire array.
Using calculations from the ARRL Antenna Book, several vintage books on wire arrays and measuring up the remainder of the downed antenna, measurements were calculated.
With a son, Tom KC9JGD, I measured off the critical measurements on a warehouse floor, and proceeded to build the antenna.
As my home QTH is 113 miles by car, then a 40 minute ferry boat ride, & followed by a cross-island 10 mile drive to the W9EVT QTH, how to package the new Bruce Array was a large concern.
As a Bruce Array is angular antenna, shaped something like this one by SM5JAB:
But with the feed point at the center of the center vertical
It isn’t an easy shape to transport.
What I did was to build it straight, attaching ropes & corner fixments at the appropriate distances from the center, and then carefully tagged each spot with where is connected to.
KC9JGD and I carefully rolled the antenna up on an old coax cable drum, throwing it in the back of a pickup for the trip North.
Once on the island we enlisted KC9FVR, W9EVT, & two friends to help KC9JGD & I pull out, rig and get the array out laying on the orchard grass.
It was a quick lowering of the two motorized crank-down towers, rigging using a small Terex Boom Lift and the Bruce Array was soon on the air.
I’ve not figured out how to photograph the thin copperweld wire antenna yet, but somehow I hope to get some pictures up to show how this Bruce Array went together.