This summer was a summer of antenna pattern measurements. We started off with something relatively simple, a 2 element beam cut to 1420MHz This was the antenna normally used on the signal squirter. Our reasoning for measuring this antenna was that none of us had ever really done an empirical study of antenna patterns, and a small antenna seemed to be a logical first step before tackling the Big Ear.

The setup used for testing the antenna consisted of a transmitter and a receiver. The transmitter was a 1 mW signal source with a 16dB amplifier borrowed from the telescope. The signal was transmitted through the east feedhorn (which was not currently in use). Our receiving setup originally consisted of only the HP power meter and the beam at the end of a 200' extension cord. After taking a few readings and seeing the wild fluctuations we quickly decided that a BP filter was needed. The final setup included a 1390-1430MHz BP filter which eliminated our RFI problems caused by a receiver with an effective bandwidth of 10GHz. At the receiving point we rotated the antenna itself, taking measurements from the power meter every 10°. We then plotted the pattern on polar graph paper and came up with a nice looking plot. Now came the time to do "the real thing" and this antenna would be considerably more difficult to rotate than the little 5" Yagi.

In order to avoid rotating the feedhorns (which was never considered) we were planning to move the receiving antenna around the feedhorns, at a constant distance, and with an accurate sense of direction. Doing this with the equipment we had took some mathematics and some very complex measuring devices. For distance we used a 410' piece of nylon cord (which was attached to a strain gauge to assure a constant tension). The angles were determined by calculating the correct 5° cord lengths for a circle with a 410' radius. This method worked and proved to be quite accurate as we were later able to verify by using a transit provided to us by Dr. Barnhart.

As we began measuring the feedhorn pattern our receiving setup progressed. We decided, however, not to use the Yagi as the receiving antenna, but instead used a horn-type antenna similar to the skyhorn. Our power source progressed from the 200' of extension cord cobbled together from the RO's supply, to the impressive 500' cord from ESL (which, assuming the parabola is still 410' from the feedhorns, is considerably longer than the reported 500'), and finally to a small lead-acid battery hooked up to the inverter lent to us by Steve Willard which was the best, and final source of power. For the first day of readings the horn was simply held above the ground a few feet, which proved less than ideal. So, a way was needed to raise it up high enough to not be affected by the ground plane. The solution came in the form of a forklift-like piece of equipment from ESL which was laying unused around at the RO, which they call a "genie". This enabled us to raise the horn to a grand height of 14.55' (still not in the principal plane, but high enough to not see too much reflection from the ground plane). This setup provided us with a decent portable receiving device, helping us map the far field from 20° west to 20° east (everything on the ground plane).

From the measurements we took in the first 25 weeks we were able to plot the antenna patterns for both the east and west feedhorns from 20° E to 20° W. We also measured 25' distanced on the 0° line in order to determine where the far-field pattern began. It was calculated that the west feedhorn is more sensitive than the east by about 1dB, and that the far field begins at appr. 275'.

The remaining week and a half was spent trying to figure out how to do something useful in the field, since time was quickly running out. This proved considerably more difficult than our measurements on the ground plane before. In order to get true measurements we needed to be in the principal plane of the antenna, which in the center of the parabola is at 35'. We also needed to needed to be at a height higher than 14.55' when we went off the ground plane to measure the patterns in the field. Erecting a structure 35' high, which is stable, wind resistant, and portable is not an easy task. We went through several iterations starting with 3 sections of 10' aluminum mast with the 2 element Yagi (modified to be essentially a 3 element Yagi by the addition of a reflector made out of an old high voltage sign). This structure proved to be quite unstable and was never used for measurements. The second structure concerned the genie used for the original measurements with a section of 10' mast attached to it, along with the addition of a discone antenna because the Yagi had proved to be too directional for a true field probing. In order to make this structure more portable it was clamped to an old 2 wheel trailer which was lying around, bringing the total height to about 27'. Upon taking this device into the field and taking some measurements we found nothing. The needle on the meter never budged. The sidelobes were less than -75dB which is the range of the meter. On the next day we had a preamp ready to use with the system. When we brought the system into the field we found that we could see a signal (with an extra 35dB of amplification), but that it varied too much because of the antenna swaying in the wind due to the instability of the structure. We now had one last option; we built "The Thing". The Thing consisted of a base of 4 12' 2x4's, with some support sections and 4 swivel wheels on the bottom to make it semi-portable. The tripod was bolted to The Thing, with 30' of the steel telescoping mast provided for us by Dr. Dixon. The mast was guyed in eight places to the ends of the 4 2x4's (which were layed out in a configuration similar to that of a railroad crossing). The Thing is stable, tall, and amazingly enough, is even portable. Unfortunately, The Thing was completed too late for us to really have a chance to use it much. We were able to see that it should be stable enough to use for measurements, but that was all really. A few more guys wouldn't hurt either.

Over the past month we have had a lot of fun and have learned quite a bit. We would like to especially thank Steve Brown & Russ Childers for working with us and teaching us throughout the summer. The teaching we have received will not fall on deaf ears, we promise! We would also like to thank Dr. Barnhart and all of NAAPO for giving us the opportunity to come here this summer and for providing us with experiences that will last a lifetime.

Sincerely and with all appreciation; Chris Slack & Malinda McKay.

SETI Office
M.S. 303-401
Jet Propulsion Laboratory
Pasadena, CA 91109
phone: (818) 354-6270

VOYAGER 1 and 2: The two Voyager spacecraft are continuing their Interstellar Mission, having remotely detected the heliopause, the boundary between the solar magnetosphere and interstellar space, for the first time last month. Voyager l, launched September 5, 1977, is currently 8 billion kilometers (5 billion miles) from the Sun after flying by Jupiter and Saturn in 1979 and 1980; Voyager 2, launched August 20, 1977, to fly by Jupiter (1979), Saturn (1981), Uranus (1986) and Neptune (1989), is now more than 6 billion kilometers (3.9 billion miles) from the Sun.

An otherwise idyllic setting for the RO Social Event of the Year was marred by the repeated attacks of a large water creature, apparently a resident of Loch Dixon.

Affectionately dubbled "OH2131" by Dr. Dixon, several eyewitness accounts at the site describe the creature as being some 110 meters in length, and at times emitting a soft growl, loudest at roughly 21 centimeters.

Several RO volunteers and their children were menaced by the creature. At one point, it grabbed volunteer Tom Hanson and dragged him to the far side of the Loch, where it is rumored that poisonous turtles nest. Tom managed to extricate himself from the jaws of the monster and swim back to the safety of the dock.

Talk of a conspiracy floated about as Dr. Dixon was witnessed placing children in a dock-side "tenderizing unit" before sacrificing them to the creature. When questioned by this reporter, Dr. Dixon refused to comment, saying only that "I am not allowed to discuss it". In an obvious attempt to avert everyone's attention from the creature, Dr. Dixon conducted several tours of his beautiful new home.

A lack of natural food sources seems to be the reason for the sacrifices. A conspicuous lack of fish in the Loch was evident, and the barns and stables are devoid of cows and horses. Apparently, the only thing left for Dr. Dixon to feed his creature is RO volunteers. What better way to ensure a good meal for it, than to stage a party for the volunteers?

The creature has evidently reproduced, for several of its young were seen swimming about in the Loch. One witness, who asked not to be identified, described the young as appearing to him as "extremely large 'tadpole' type creatures; as if regular bullfrog eggs were hatched in the cooling towers of Chernobyl". Some of the young were seen swimming in the tenderizing unit, and one of them spat acid at the party's attendees, in an attempt to blind them so they would fall into the Loch, only to become meals for their parent.

Many attempts were made to capture the creature's image on film, but most of the pictures mysteriously came out either blank or badly out of focus.This reporter, for one, wants to know the facts. What is this creature of the Loch? Why is Dr. Dixon secretly harboring a seemingly intelligent life form? Researching minds want to know!

The meeting began at roughly 10:15am. Those in attendance were Brown, Phillips, Slack, Dixon, John & Ken Ayotte, Schumacher, Stephens, Mrs. & Malinda McKay, and Campanella.

Brown reports that he and the summer interns have been making measurements of the feed horns.

Hanson reports that we are being urged to remove the old computer punch cards from Baker Systems. There has been no recent change in the card-to-tape project.

Schumacher reports that he has continued his work on the KLT, producing more output. He feels that he has found at least one case where the KLT will outperform the FFT in signal detection.

Campanella has been travelling lately, and has had little time for his RO duties.

Slack brought Russ Childer's charts of the CASS A region, showing both point and diffuse sources. They need a comparison chart to determine if some of the point sources are previously uncatalogued. He reports that he has been busy measuring the feed horns, and has plotted their response at varying distances. He has found that the response does not peak at the center, but about 4° off. One possible reason may be the "blinders". He plans to test the horns with the blinders removed to test his theory.

Stephens comments that he attended the meeting as an observer. He also commented on the feed horn measurements, offering suggestions.

Phillips brought a modem program that sets a PC's clock to the USNO's Atomic Clock. He also brought the results of his RFI survey of some 3 years ago, as the seed of a potential RFI database for the detection system to query in case of a suspect signal.

Ken Ayotte reports that he has constructed a power supply for his receivers, and that his education grant proposal from NAAPO has been accepted. John reports that he is still working on scanning the Ohio Survey into PC format.

Mrs. McKay has started working on the weed control problem, and reports that her husband would like to get involved, possibly assisting Tom Hanson on the card-to-tape project from his home. Malinda has been working with Chris Slack & Steve Brown on the feed horn measurements.

A presentation on Fuzzy Logic was then given by Chris Slack, with a slant on the possible future use of this field in the area of signal detection. He also feels that Fuzzy Logic could be useful as a means to separate RFI from signal. A general discussion on the subject followed, with many possibilities floated about as to the application of Fuzzy Logic to radio astronomy. He promises to continue working in this field.

The meeting broke at roughly 11:40am, with most going off to their respective tasks.

ed. note: Since I wrote this article, I have received a copy of the bill mentioned above. I will send copies of it to anyone interested. Additionally, I have learned that the bill is currently under consideration in the Committee on Commerce, Science, and Transportation. I will also provide the names and addresses of the committee members to anyone wishing to contact them for the purpose of expressing their opinion on this matter.

The City of Delaware, Ohio, just north of Perkins Observatory & "Big Ear", has lately been considering the inclusion of lighting restrictions to their zoning codes. The lighting regulations, similar to those already adopted by Liberty Township, just west of the observatories, strictly limit lighting amounts and take specific issue with light trespass, as well as demanding the use of full cut-off type fixtures.

The final decision by the Planning Commission was delayed due to testimony by 2 local electric company representatives, who stated that the use of Low Pressure Sodium lamps were potentially dangerous, subject to explosion. Research on this possibility showed that there is no undue safety concerns in their use, however.

At their regular meeting in July, the Planning Commission voted unanimously to send the proposal to the City Commissioners with their favorable recommendation to approve it into law. The City Commissioners will meet the last Monday of August to consider the proposal.

The meeting began at roughly 10:15am. Those in attendance were Barnhart, Phillips, Dixon, O'Connor, Mrs. McKay, J & K Ayotte, Janis, and Childers.

Barnhart reports that Steve Brown is away on vacation.

Dixon reports that he is almost ready for the trip to Santa Cruz, and Ayotte brings more transparencies for his talk there.

Phillips brings some 8" diskette protectors he is donating, as well as a couple of years worth of "The Spacewarn Bulletin" he donates to the archives. He reports that the Electronic Journal of the Astronomical Society of the Atlantic will carry a blurb on the RO, allowing readers of that journal to obtain Signals on a regular basis in exchange for some sort of donation, as well as how to purchase sets of Cosmic Search. He has also obtained a piece of mathematical software that solves equations that he will donate to the cause.

Ken Ayotte has constructed a 600MHz helix array, and brings charts and pictures of it.

Mrs. McKay reports that her daughter Malinda is safely off to Japan, and that her husband has begun assisting Tom Hanson on the card-to-tape project from his home.

Childers reports that he and O'Connor has been working on the guy wire project since roughly 8:15am today, and has completed the connections to the ground anchors. Much welding was necessary, but all there is left to do now is to hang and connect the replacement guy wires. He also brings a new photo of the mystery source, as well as a graph of the hydrogen cloud he's been observing.

O'Connor reports that he is now ready to tackle other projects.

The meeting broke at roughly 11:30am. A tour was directed by Dr. Dixon for the Mid-Ohio Research Associates, a group interested in UFO research.

A busy summer has occupied the RO staff and an exciting fall is just around the corner. Our two student interns, Malinda and Chris, have had their taste of good hard work. Not surprising that they learned that sometimes the course of true science involves an entire day to track down a single hex nut to secure an RF connector to a portable antenna. Valuable measurements of the feed horn antenna pattern were carried out with their able assistance. They both gained valuable experience in rf field strength measurement, surveying, mast building (to get the test antenna closer to the middle of the parabola thus to the middle of the horn pattern) and data analysis and display.

Chris left on the last day of July to prepare to start the fall term at Clarkson College in Potsdam, New York. Malinda left the 5th of August for a trip to Japan where she will watch for the anticipated spectacular Perseid meteor shower. She has also indicated she will check out the Japanese radio astronomy situation, at least from the standpoint of the knowledge of the average Japanese citizen. We anticipate her return before the start of the fall school term and expect her to continue her volunteer work with us through the coming year.

For those of you who read this Corner last issue, I would like to mention that NAAPO chose to grant KEN AYOTTE seed money to explore new technology amplifiers for possible use on his home built radio antenna. We have begun to receive reports at our Saturday working sessions on his progress. Among other things he reported last week is a 4 element helix array. The pictures he presented demonstrate a rapid advance in skill and speaks well for the commitment KEN is bringing to his project. We will publish his project report early this fall so you can all get the straight scoop on what he is attempting and the progress he is making.

A number of tasks are coming around this fall. The horn pattern project, the H cloud scans (requiring total power detection leaving the pattern recognition and LOBES programs on standby) and the antenna temperature and aperture efficiency measurements using Cass. A are drawing to a close. The instrument will return shortly to the survey mode and SETI data will again take the majority of the observing time. Russ Childers has the data processing programs humming along.

The PC simulated strip chart recorder is now running without a glitch. It did shut down every midnight for a time. The reason was not clear and the fix (found serendipitously by Chris Slack) was to insert an innocuous inquiry statement into the program. The statement asked the program to do nothing and the glitch disappeared as long as the statement was in. Upon removing the statement from the program the machine stopped at midnight. Since reinserting the statement the recorder has run without a hitch. Great power of suggestion.

Next issue we look forward to a report from BOB DIXON on his presentation at the Santa Cruz SETI conference. He is presenting a paper on the RO ARGUS Project and its application to SETI and all of radio astronomy. Many volunteers came together in the last few weeks to help get this paper ready for the conference. Special thanks should be expressed to CHUCK KLEIN and RUSS CHILDERS for generating new graphics, JOHN AYOTTE for a simulated ARGUS display, BILL MILLER for overhead transparencies and slides and STEVE BROWN for new data on the computer load requirements. Much of the material is being sent to Santa Cruz after Bob's departure from central Ohio.

ADDRESS LABEL HINT

Last issue I indicated a desire to pare back a bit on the SIGNALS mailing list. Most of our readers are committed to supporting our effort, either with their good wishes or in more tangible ways. Donation of time and/or money is always greatly appreciated, though sometimes not adequately acknowledged.

In an attempt to assess the commitment of those from whom we have not heard in a long time it was suggested last issue that an opportunity exists to freshen your contact with NAAPO, the radio observatory or an individual working with us.

Our intrepid editor kind of messed up my illustrative mailing label which is designed to give a hint to the people from whom we have not heard in a while. I repeat that label here in hopes that Earl will get it right;

Dr. P. E Barnhart	*
Dept. Phys/Astron	*
Otterbein College	*
Westerville, OH 43081	*

NASA's Mars Observer spacecraft returned its first image of Mars taken last week when the spacecraft was 3.6 million miles (5.8 million kilometers) from the red planet.

The photograph was taken using the Mars Observer Camera's (MOC) high resolution narrow-angle telescope as a technical check-out of the camera, the data management system and other systems on board the spacecraft and on Earth, including NASA's Jet Propulsion Laboratory, Pasadena, California, and the MOC operations facility at Malin Space Science Systems, Inc, San Diego.

Mars Observer will orbit Mars on August 24 and global mapping operations will begin December 16.

The London Daily Telegraph reported in November that the new state-of-the-art telescope operated by NASA and the Vatican Observatory in Arizona will be used to search distant galaxies for signs of intelligent life so that, if any humans are discovered, the Catholic Church will be prepared to baptize them.