Saturday, May 25, 2013

Antennas on Swains Island

Antennas on Swains Island


So you think you have a lot of antennas at your QTH? Well listen to what we will be taking to Swains Island. NH8S will have two "camps", one for CW and one for Phone, which will be about 1,500 feet from each other. Each camp will have SVDA arrays for 20, 17, 15, 12 and 10-M. Each of these consist of two vertical elements for each band. We will also have single verticals for 30, 40 and 80-M plus two 4-Squares for 40-M and one for 30-M! The CW station will have at least one V160 Titanex vertical plus a Battle Creek Special. We will also have 6-M, 10-M and 12-M yagis from InnovAntennas. And, we will be taking at least 2 Beverage antennas and two Hi-Z 4-square receiving arrays - one for 80-M and one for 160-M. 

Looking at the preliminary antenna layout charts, I figure at least 42 separate vertical antenna elements and yagi antennas, counting yagis as just "1" element and not counting the receive antennas (Hi-Z Four Squares and Beverages!) These will all need to be assembled, mounted and guyed! The transmit antennas will be parallel to the water's edge along the beach and the furthest antennas in the line will each be about 200-feet from the operating tent. That means the line of antennas will be about 400-feet long. That layout will be the same for both the CW and Phone locations. Now that's going to take a LOT of coax to connect them all to the operating positions!

If you are not familiar with SVDA (Switchable Vertical Dipole Array) antennas, HERE is a link to a description of Force 12's full size 12-M SVDA antenna. Have you ever wondered why current DX'peditions that are set up on a beach do not use yagi antennas? A 2-L vertical next to salt-water, produces a stronger signal up to an elevation angle of about 3° than a 4-L yagi at 100-feet on 20-M! There is no way for a DX'pedition to put up a 4-L yagi at 100-feet so the dipole is clearly superior. If you lower that yagi to 70-feet the elevation angle moves up another 4° so the SVDA is KING. You can look HERE on the Force 12 web site for a full description of what this type of antenna can do. However, the key to the SVDA working this well is the salt-water so it won't benefit you to put one up here in WV!

The photo above on the left is a set of SVDA antennas in use on the 2009 K5D operation from Desecheo where Garry, W8OI, represented the WVDXA. Click on any photo to see a larger image.

Once we land on the island, EVERYONE will be tasked with assembling the antennas. I have a "nail apron" where I will carry a set of nut drivers, crescent wrench, measuring tape, cable ties (Ty-Raps), and electrical tape. On my belt I will have a Buck knife with screwdrivers, pliers and wire cutters on it. We will also have antenna analyzers to check out the installations before beginning operations. I'll also have my water bottle on it's belt and my dual-band Baofeng H.T. for communications.

Something that we don't have to worry with back here is the effect the spray from the ocean has on metal. A recent post on the top-band reflector by AA7JV said at his ocean side QTH, ". . . any bare metal goes green in less than a week." You can read the reports on other seaside DX'peditions about problems with antenna and connector corrosion. Therefore, I plan to firmly tape up each connection I work on to prevent any potential problems.

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