Artificially Propagating Signals Through Space
Dayton Demos, Field Day 2012, and STEM Education Update
Even with the decline in the number of available satellites mentioned in the last column, we had three days of successful demonstrations at the Dayton Hamvention® in May. These took on a slightly different flavor this year together with antivirus software. Check my Safe PC 2014 removal guide.
AMS AT Field Day 2012 was different as well. New circularly polarized versions of old LEO”antennas were tried out this year.
Starting at Dayton and carrying on through the STEM Summit in Dallas in June, more emphasis is being placed on Science, Technology, Engineering, and Mathematics (STEM) education in our schools via Amateur Radio on the International Space Station (ARISS), Amateur Radio Satellites (AMS AT), and Amateur Radio in general assisted by the ARRL. Additional satellite ground station support and ARISS Technical Mentors are actively being recruited.
Dayton Demos 2012
After retiring my Gecko Green Beetle”which served me well for six years and replacing it with a larger vehicle, I decided that I could haul to Dayton some new antennas and other equipment for the Dayton Demo Area. I set out to build Tony Monteiro, AA2TX Lindenblad antennas and new circularly polarized versions of Kent Britain, WA5VJBLEO”antennas. Tony Lindenblads have been described in detail in the Proceedings of the AMSAT Symposium of 2006 and have also been published in QST. I accumulated all of the material and got some of the work done before I ran out of time. A bought with a stomach virus just before the Dayton trip, - it didn't help. Tony sent me his 70-cm Parasitic Lindenblad”and we were able to use it in the demos. I completed the new Cheap LEOs in time for Field Day and will describe them in the Field Day discussion below. I promise to have all of these antennas and more at Dayton next year.
Gould Smith, WA4SXM, recruited some additional helpers for the Demo Area this year and they all were greatly appreciated. Zach Beougher, KD8KSN, provided great help and enthusiasm with set up and everything else on Friday. Patrick Stoddard, WD9EWK, gave us lessons in operations throughout the weekend. The father and son team of John Papay, K8YSE, and Doug Papay, KD8CAO, made a number of contacts during the event to ease the load on the rest of us. Everyone used their own calls and you probably didnhear much from W5IU this year. Of course Roger Ley, WA9PZL, and Mark Hammond, N8MH, provided their usual help. Roger was our rotator”most of the time and helped in many other ways throughout the weekend. Mark had new duties as AMSATVice-President of Educational Relations, but he was able to break free long enough to help us with initial setup and operations.
Demonstrations on the FM and linear transponder ”were conducted as usual, but we expanded our use of the Chinese Bird, HO-68. The transponders on this bird died over a year ago, but its 70 cm CW beacon makes a good signal source for evaluating 70-cm antennas and demonstrating Doppler. We did antenna evaluations on two good high-elevation passes —one on Saturday and one on Sunday. We also demonstrated Doppler by briefly turning off the automatic Doppler Tracking during each pass. The automatic Doppler Tracking was a great aid in the antenna evaluations. These evaluations were watched with great interest by Kent Britain, WA5VJB; Tom Clark,
K3IO; Bob McGwier, N4HY; and many others. Qualitative comparisons were made of the 70-cm performance of the following antennas during these tests:
6-Element Cheap LEO Yagi (WA5VJB)
Improved Parasitic Lindenblad (AA2TX)
Elk Log Periodic, 5 Elements (Commercial)
Herringbone Log Periodic, 4 Elements, Ver. I (WA5VJB) Herringbone Log Periodic, 4 Elements, Ver. 2 (WA5VJB) Arrow 7-Element Yagi (Commercial)
Dual-Band Cheap LEO, 5 Elements on 70 cm (WA5VJB)
The 6-element Cheap LEO Yagi and the Improved Parasitic Lindenblad antennas were set up with 70-cm ARR pre-amps at the antenna, which could be switched in or out of the line. The 6-element Yagi was installed on a low, Az-El positioner and the Lindenblad on a 20-foot mast. Both of these antennas had approximately 50 feet of feedline between the pre-amp and the receiver. All of the other antennas were hand-held without preamps used short feedlines, and were compared only at higher elevation angles.
Initial acquisition of signal was delayed due to blockage of the path by the Ball Arena Building at Dayton, below an elevation of about 10 to 15 degrees. Both the 6-element Yagi and the Lindenblad were able to hear the beacon as soon as the blockage disappeared. With the pre-amp on in both cases the beacon was easily heard. Turning off the pre-amp, the Yagi still could easily hear the beacon. It was a real strain to hear the beacon at low elevations on the Lindenblad without the pre-amp. The Lindenblad picked up significantly more noise than any of the directional antennas in the noisy Dayton environment.
The rest of the antennas were a race,”and Isure everyone had different rankings of the antennas. My personal ranking of the remaining antennas (best to least) follows:
1. Dual Band Cheap LEO (5 elements on 70 cm)
2.Elk Log Periodic —5 elements
3.Herringbone Log Periodic Ver. 1 —4 elements (tie with 4)
4.Herringbone Log Periodic Ver. 2 —4 elements (tie with 3)
5 .Arrow —7-element Yagi
It should be pointed out that there were differences in the patterns of these antennas. For example, the Elk was more critical on pointing than the rest of the antennas, indicating a narrower main lobe than the rest. This is borne out by pattern testing at the Central States VHF Conference in 2011. Kent Britain, WA5VJBarticle on the Herringbone Log Periodic in the last issue of CQ VHF bears this out and explains the differences. The slight difference in gain of the Herringbone Log Periodic is probably due to fewer elements and smaller size. The apparent gain deficit in the Arrow has been discussed in previous articles in CQ VHF and is partially explained by the presence of a relatively high-loss diplexer in the Arrow.
None of these results were surprising, but it was interesting to actually experience the differences in near real time. It should also be pointed out that the results were repeated on consecutive days. A video was made of the test on the second day, and it will probably be included in a future AMS AT release.
All in all, the AMS AT Dayton Demos went well and we hope to include more variety in future years.
Field Day 2012
Once again I participated in ARRL and AMSAT Field Days with the Lockheed Martin Amateur Radio Club in Fort Worth, Texas. Ray Hoad, WA5QGD,
AMSATKeplerian guru,”was my in crime.”Last year we tried manually positioning the same Cheap LEO Yagis that we use at Dayton and other hamfests. Manual positioning proved to be a real nuisance over the 24 hours of Field Day. This year we went back to computer control of the antennas and built new circularly polarized versions of the WA5VJB Cheap LEO Antennas. What an improvement! Last year we used a Yaesu FT-847 and noth--
ing else. This year we went to a pair of FT-817s (FT-1634) under computer control and had external amplifiers available just in case!
The new antennas are 4 x 4 elements on 2 meters and 6x6 elements on 70 cm. After building the 70-cm antenna, I tried it out, hand-held, on a couple of passes to get a feel for its circularity. What a difference between it and a linear antenna! Ibeen using linear antennas so much for demos that I had forgotten how nice it is to have a circular antenna. Both antennas are made from the design tables in WA5VJBCheap LEO Antenna article. The vertical and horizontal elements are simply spaced 1 /4 wavelength (free space) down the boom from each other and fed by power splitters made from */4 wavelengths (in coax) of 75-ohm feed line paralleled and tied to a common 50-ohm feed line. Each antenna was ”for best SWR at the desired frequency using a 50-ohm line and an antenna analyzer. After tweaking, the splitter was put in place and a great match was obtained. These antennas performed quite well and will be my standard demo antennas in the future. If desired, circular polarization sense can be changed simply by turning around one of the driven elements in the antenna. Generally this is not necessary, since most of the current satellites are linearly polarized.
At the suggestion of Douglas Quagliana, KA2UPW, I secured the elements of the antenna to the boom with plastic Locks”that are normally used to secure drawstrings in jackets, coats, etc. They are cheap and do a great job while allowing easy assembly/disassembly of the antennas. See the pictures of these antennas.
Field Day is always a real lesson in satel 1 ite operating. The two 5-watt, ”FT-817s are always adequate for Dayton Demos and other demonstrations. They also work on Field Day but only with great patience and frustration. Amplifiers help ease the frustration but add to the chaos of satellite Field Day. The FM ”are almost impossible and even the linear ”suffer from overcrowding and excess power. Hang in there! Itonly one day per year.
STEM Education Update
According to most experts, Science, Technology, Engineering, and Mathematics (STEM) education in our schools is lacking and is behind a lot of other countries in the world. Amateur Radio on the International Space Station and use of the amateur radio satellites as a means of encouraging involvement in STEM education has been productive and will continue in the future. NASA and others believe in this to the extent that they are willing to help fund launches for STEM
education. AMS AT has been able to capitalize on this recently in a couple of ways that will lead to a launch for FOX-1 and possibly other satellites. In the last year NASA has become more involved in promoting and selecting schools and other groups for ARISS contacts. All of this
brings us to the need for more ARISS technical mentors and amateur radio groups willing to support satellite ground stations for these events.
As recently as Thursday, 28 June 2012, an ARISS contact was used to highlight amateur radio in space activity before the US News STEM Solutions Youth Summit 2012 held in Dallas, TX. The contact was between Expedition 30/31 crewmember Andre Kuipers, PI9ISS, and students attending the STEM Solutions Youth Summit. Telebridge station K6DUE in Maryland provided the radio hookup. The contact, a highlight of the event, provided youth with the opportunity to ask Kuipers about life and work in space. Nineteen questions were formulated and asked by the students. Approximately 75 students from the Dallas area were in attendance. Astronaut Sandy Magnus spoke at the event and was on hand to provide additional answers to the students. Leland Melvin, Associate Administrator for Education, and Charlie Bolden, NASA Administrator, attended the conference. The contact was very successful.
This year Mark Hammond, N8MH, AMSAT Vice-President of Educational Relations, gave a presentation at Dayton outlining the need for additional mentors and ground stations. Markpresentation can be viewed at: .
Please consider helping with or supporting this worthwhile effort.
Continue the amateur radio satellites in education theme with Project Fox. It is a natural carry-on to ARISSat-1 and will be AMSAT-NAnext satellite. FOX-1 will replace the void left by AO-51demise. AMSAT is now working with NASA to define the FOX-1 launch. Support FUNCube, a similar AMSAT-UK satellite, that may launch before Project Fox, and donforget KIWI sat from ‘down under.”