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Testing 40m 4-Square Array in CQ WPX SSB 2019

Testing 40m 4-Square Array in CQ WPX SSB 2019

Andy VK5AKH driving VK5GR in CQ WPX on the 4-square on 40m

The first major new antenna for the DXpedition has been completed and was taken out into the field for its first on air trials this weekend during the CQ WPX SSB contest.

The Array

Our 40m 4-square array, designed and built by Oly VK5XDX will take full legal power and then some. We verified that the directionality definitely works, being able to switch and see an immediate change in received signals between NA, EU and Asia across the contest. Unfortunately for now, switching involves going outside and replugging the antennas into different ports of the hybrid and phase shifter. We are looking at ways of building a relay switch box to add to the antenna so we can switch it back in the shack.

The array is supported by one of our equipment partners. The 75ohm phasing lines between the elements used cable sourced via Messi & Paoloni in Italy, who make foam based light weight coax that can still take the power needed on our station. This contributes to the whole array (minus the star droppers) weighing in at less than 14kg. It was designed to break down into lengths less than 1500mm so that it can be carried on commercial airlines as oversize baggage.

The Ultraflexx 7 50ohm main feeder used also came from M&P. This cable has roughly half the weight of traditional RG-8 – highly important for a weight limited expedition.

Results on the Air

During the contest, we were frequently asked what the antenna was and were complimented on our signals. We were happy to be able to often get stations in Europe and North America to reply with only 1-2 calls, and were pleased to be able to work some small pistol stations on 40m in the USA during the early evening (our time). It all bodes well for our 40m signal on Tonga in September!