4-Squares on 40 and 30m – Wow!

One of the projects we embarked on for the expedition was to take a 4-square antenna for 40m with us. Then we added 30m to the mix as well. These two antennas have really taken the stations capabilities to the next level. Without the 40m one in particular our SSB activities towards Europe would have been very difficult indeed.

During the CQ WW RTTY contest the 40m 4-square was invaluable in trying to separate the simplex pileup on RTTY as well. The power to switch in 20-30dB front to back and add gain to the signal was fantastic.

40m 4-Square

Oly VK5XDX took the lead in developing the 40m 4-square antenna and did a fantastic job. Based on 4x 12m fibreglass fishing poles, he used an elevated radial system to maximise efficiency.The controller and phase shifter was all home brewed especially for this expedition.

What we hadn’t bargained on initially, but which has been invaluable in the expedition has been the power to take one of the 40m elements by day and tune it to 15m as an omni. We used this to great effect to enable multiple high band stations on the air at the same time using the antennas we had.

30m 4-Square

The 30m 4-square was the brainchild of Steve VK5SFA. Using similar fundamental designs as 40m, Steve developed this antenna using 10m fibre glass fishing poles. Again an elevated radial system was used and results were also impressive.

Unfortunately, we weren’t able to capitalize on this antenna for a long. Initially due to running out of space on the site, we installed it across the driveway. That proved a problem when rapid access was required for the fire truck. After hastily being lowered to the ground, it was decided to re-erect it as a single 30m vertical which is what we have run for the rest of the expedition. It was disappointing that we couldn’t use it longer but it worked great when it was in the air.

We also made a modification to this antenna and found that it could be made to run on 10m with a 100:50ohm transformer and a tweak to the element length. It was great to be able to multi-purpose these antennas on site during the expedition.


This entry was posted in 2019: A35JT OC-049 Tonga. Bookmark the permalink.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.