It’s about two weeks until Field Day. I’m captain of the 80/20 cw station, and I’m trying to pull together plans for the station. The club has done this event many times in the past, and there is plenty of experience to tap into, which is good, since this is my first time running anything at Field Day. Pete K6BFA is the top boss for the event, but there are a large number of people involved in logistics. A large chunk of the planning took place last month during a walk-through at the site, Burke Lake Park (see map of proposed station locations and antenna deployment). Due to work commitments, I was out of the area on that day, and on every weekend since then. Earlier today, I had a chance to scope out the site for myself. Tomorrow night, I’ve invited people who have signed up to work the station during the contest plus a few members of the planning committee over to my house to talk about antennas for the 80/20cw station, but I wanted to get the lay of the land before the meeting.
The present plan is relatively limited — to run a long wire antenna from a mast near the 80/20 station to a tall tree. It sounds like this would be reasonable for the 80m, although maybe not optimally high near the station end. I’m not sure it would work well for 20m. We have a number of other antennas available to us, plus a push-up 40-foot mast. Also, the station is near the spider beam, which is designated for the ssb station, but perhaps could be shared (?). In pow-wowing about antennas tomorrow night, my goals are:
- Put up a single and reliable antenna so we are ready to go when FD starts.
- Not interfere with the other stations.
- Lay out a strategy for best use of our resources at different times during FD.
- Incorporate any experimental suggestions that are not likely to interfere with #1-3.
I went to the site of the 80/20 station, and spun around, capturing the landscape around the site with my cell phone’s camera. The site is a bit lower then the surrounding area, and there is a slight grade upwards to the west. I am initially facing west. At 0:03 seconds, facing the non-40SSB. At 0:06, facing 40/15SSB support tree. At 0:09, facing the tall tree planned to support? the 80/20. Another potential support tree is masked in background at around 0:11 seconds.
I also took some still photos, thinking about trees that might make good antenna supports. Starting with the current plan, there is a really tall oak tree just across the road to the East, in the direction of the minigolf course. We could use a 40 foot mast towards the station end to give it some height. I counted 132 paces over to the tree, so something like 130 meters. According to the layout picture on google maps, the antenna is about 160 feet, and the support rope about 185 feet (but considerably longer in practice, since it has to go up to the top of the tree and the antenna wire will slope upwards, so not all of its run will contribute to the horizontal distance).
The advantage of this layout is that it should be dead simple to set up. An ICOM AH-4 antenna tuner would be at the tent, tied to a ground, and the single long wire would run up to the mast and then over to the tree.
A number of people have volunteers other antennas for the effort as well, including Ian N0IMB’s Buckmaster OCF dipole, my G5RV, or Byron W4SSY’s 80/20 fan dipole. Of these, the fan dipole may be the most attractive because it is resonant, and perhaps to least likely to interfere with other nearby stations. The difficulty with these antennas is getting the feed point near the 80/20 station.
The other end of a dipole could be suspended from the large tree just up the hill from the station. According to the site layout, this tree would also support an antenna for the non-40 ssb station. The tree could be used to support a rope, so the two antennas would not be so near each other. Additionally, the two antennas would be near right angles to each other. This end of the antenna would also be near the spiderpole, though, so perhaps that would be a problem.
Looking eastward from the site of the non-40 ssb station, the “long wire” tree is to the left, and the tree proposed as the other end of the dipole is on the right in the background. Closer, the trees on the right are the site for the 80/20 cw station, so the dipole would run in a straight line past the station, requiring a 50-100 foot feedline if we played it right with the ropes on each end.
In addition to these antennas, Byron has volunteers the use of his 20-meter Moxon, which has been used several previous times at Field Day. John K4US has also made available a 40 foot push-up mast. We’ll have to figure out how to best use all of this equipment tomorrow night.
Guess I should get some soda and chips for tomorrow night…