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REFLECTIONS ON 40+ YEARS OF IONOSPHERIC RESEARCH

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  • humlobotomist
    http://www.ee.psu.edu/cssl/ferraro.html I have been asked by Dr. John Mathews to write a few words about the early days of the Ionosphere Research Laboratory.
    Message 1 of 1 , Apr 7, 2005
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      http://www.ee.psu.edu/cssl/ferraro.html

      I have been asked by Dr. John Mathews to write a few words about the
      early days of the Ionosphere Research Laboratory. As a member of the
      current laboratory, CSSL, I have been given this honor because I have
      just retired and have been around for a long time. Actually I have
      just completed 41.4 years of service to Penn State and have been a
      member of the IRL and CSSL during that time. Remember that the memory
      fades a bit with time, so while I will attempt to be accurate, those
      readers that are from the days of IRL can feel free to write to me if
      something I refer to is not quite correct.

      Those of you who have been around for awhile certainly know about IRL
      and the founder, Dr. Arthur Waynick. You have probably read that the
      lab was founded in the early 40s and was devoted to the study of the
      ionosphere. The major sponsor for research funding was AFCRL, known
      then as the Air Force Cambridge Research Laboratory, and our research
      monitor was an outstanding ionospheric physicist, Dr. Wolfgang
      Phister. He would visit the lab about every three months and stay at
      least two days. I vividly remember having to give a presentation to
      him for about 15 minutes, as did all staff and students, each time he
      came for a review. He had great insight and would provide us with
      some good ideas to follow through. In those days, Art would have us
      write weekly, monthly, quarterly, and annual reports so we had the
      material to present to Dr. Phister, but it was still frightening for
      the students. Those weekly reports were a good idea (now thinking
      back), and it was a great way to keep up with what everyone was doing
      in the lab. By Friday noon of each week you were required to hand in
      a report to the secretary saying what you did during the week and
      what you planned to do next week. Two to five sentences would do.
      Upon returning to the lab after lunch, you would find on your desk a
      compilation of all the reports. It made good reading and would
      strengthen your understanding of the progress being made by all
      collectively to dissect the ionosphere.

      When I think of all the hi-tech devices we have today - E-mail, FAX,
      PCs, voice mail, cell phones and laser printers - I wonder how we
      ever got anything accomplished back then when there was not even a
      main frame computer on campus. For computations (and some of the wave
      equations to be solved were horribly complicated ) we used what today
      would be called a spreadsheet. In the computational lab we had rows
      of mechanical Monroe calculators and a "computress" sitting at each
      one. They were given a large spreadsheet-like paper pad with the
      formula for each cell handwritten at the top with calculations
      progressing from the first to the last column. On the rows were the
      initial data and the results of the calculations as they were being
      processed. Not much different than Lotus or Excel except for speed
      and accuracy. A solution for a few different starting parameters
      would take days, as opposed to today's almost instantaneous output
      from your office PC. Now what did we do with all this spare time
      while waiting for a result?... THINKING TIME! This is something that
      now seems to be missing from university life due to the rush of so
      many things to keep one busy.

      In the study of the ionosphere, or more precisely to arrive at the
      physics and chemistry of the formation of the ionosphere,
      experimental tools were limited; we had no rockets to "probe"
      directly the medium being investigated nor did we have satellites
      to "look down" upon the ionospheric region. We could only rely upon
      using radio waves to probe that region. For that purpose the Lab had
      at Scotia Game Lands a large antenna and powerful radio transmitter
      for sending low frequency waves up into the ionosphere and studying
      the reflected waves that had been modified by the medium through
      which they passed. The mystery was to determine what the
      ionosphere "looked" like from the characteristics of the reflected
      waves, and that is where the wave equation came into play, for this
      medium was inhomogeneous, lossy and anisotropic. The Lab spent a lot
      of time looking for ways to solve these equations, and some of you
      might remember Dr. J. J. Gibbons who was instrumental in creating new
      methods of solutions. Maybe some of the readers might remember the
      large antenna at Scotia; there were eight 250-foot towers in a North-
      South line evenly spaced with flashing red lights on the towers. It
      was a nice view at night when driving along route 322, and aircraft
      reported using the lights as a landmark. The Lab was internationally
      known for its work with radio probing the ionosphere and by its
      distinctive blue-covered Scientific Reports which went all over the
      world. The first Scientific Report was written March 1949 by Kelso
      on "The Maximum Height of a Radio Wave in a Curved Ionosphere." What
      I believe to be the last report was #484 written February 1987 by
      Nisbet and Divany on "Instructions for running the PC Version of the
      Penn State Mark II Ionospheric Model."

      The high-power transmitter was the nerve center of the lab, and
      several of us were responsible for collecting data on absorption,
      phase height, virtual height, polarization and ionospheric motions.
      Much time was spent during the mid 50s by the experimental group
      trying to perfect the data-taking capabilities (data was recorded on
      chart recorder paper or film). At the same time the ionospheric
      physicists were restless, for they wanted "data" to substantiate
      their new chemical reaction scheme for the formation of the D-region
      of the ionosphere. I recall Art coming to me after I was working on
      the instrument for a year and saying it is time to put down the
      screwdriver and collect data. He was correct, of course, and after
      collecting a year's worth of 24-hours-per-day data (subject to
      transmitter and receiving equipment downtime) I was ready to
      interpret the charts. Fortunately along came the first main frame on
      campus, PENNSTAC, and solutions to the wave equations came more
      easily. Finally I arrived at a model of the D-region and received my
      PhD degree. I remember my advisor, Dr. J. J Gibbons, asking me a good
      question at my thesis defense; he wanted me to tell him how to
      estimate the radius of an electron. Although I spent all my research
      time in computing how many electrons there were in the ionosphere,
      this was a surprising question. The readers might want to ponder over
      this. HINT: find the electrostatic energy stored by a spherical
      charge of unknown radius R and equate this quantity to mc2; finally
      solve for R.

      I joined the faculty of Electrical Engineering in 1959 and continued
      pursuing the ground-based technique of measuring the D-region of the
      ionosphere. However I realized that the way we had been doing the
      experiment lacked height resolution while other techniques like the
      rocket probe measurement claimed to have improved upon the older
      ground-based methods. At this point I became interested in the cross-
      modulation, experiment or amplitude wave interaction, as it was also
      called. This technique was known for some time but was never
      extensively used as a diagnostic tool. It seemed to provide the much
      needed height resolution, so Hai-Sup Lee and I researched this idea
      and struck upon an improvement which we called radio wave phase
      interaction. In simple terms, we found another parameter to be
      measured that would insure better accuracy in the derived electron
      density profiles that would be even faster to collect and interpret
      the data.

      To test this concept would require an entirely new transmitting
      facility and funds were not yet available. So we did some
      modifications to the high-power low-frequency transmitter that was
      sort of on its "last legs" and Steve Weisbrod (my first PhD student)
      tackled the problem as his thesis topic. He put in countless hours
      looking at the theory and designing the special receiving equipment,
      transmitters and antennas. He was well rewarded, for at 2 a.m. in
      1962 at Scotia, he and I watched with amazement as the chart recorder
      was tracing out the first measurement of the detection of phase
      interaction. That was the beginning of my career in the area of
      ionospheric modification .

      From there we went out with a proposal to the Office of Naval
      Research requesting the funds for a completely new installation to
      measure wave interaction, and we were blessed to receive the funds.
      In the early 60s $300,000 was a large grant. However, the antenna
      installation cost $60,000, and the transmitter company designed and
      built a one-of-a-kind for $75,000. Still a lot was left for a flurry
      of student theses and numerous URSI presentations. All was not rosy
      for we were competing with the Canadians using a technique called
      partial reflections. Jack Belrose had his facility in Ottawa, and his
      results and ours never seemed to agree; this was somewhat
      understandable since his latitude was higher than ours and theory
      would say that there should be a difference, but the arguments
      continued and URSI presentations ended up with a lot of heated
      discussions. Fortunately a wave interaction facility could be easily
      expanded to do partial reflections but not the other way around. Now
      we found ourselves doing two experiments and trying to decide which
      was better and more accurate. We concluded that wave interaction was
      a superior method, and we continued to expand upon that concept.
      Cohen, Portelli, Newman, Tomko, Richardson, Sulzer, Volz, Kissick,
      Baran, Breakall, Spooner, and Resnick were some of the students that
      helped the partial reflection and wave interaction experiments reach
      completion.

      Now came another surprise. The high-power transmitter was beginning
      to cause interference to many other radio services. Our station,
      KA2XPO, being experimental, was sharing a frequency band with other
      more important services like the Canadian forest fighters and the
      Coast Guard on the Chesapeake. We set up a hot line, and if there was
      interference we would shut down. Soon managing interference problems
      was more time consuming than doing the research, and the facility had
      to shut down. However, we took this opportunity to explore doing this
      experiment at the Arecibo Observatory in Puerto Rico which had the
      incoherent scatter facility but it would not work too well at low
      altitudes, so Arecibo was a natural place to set up. Again we
      scrounged existing equipment and modified it including the log
      periodic antenna hung over the 100 foot dish for the main wave
      interaction antenna. This was not satisfactory to the radio
      astronomers who would have to wait for our 2-week experiment to
      conclude. The method did work, but there was a need for a new antenna
      devoted to wave interaction or ionospheric heating, as it was called
      then. Jim Breakall and I came up with a neat antenna farm of 32 log
      periodic antenna elements which was accepted by the observatory and
      built. The facility was in use for a number of years by several
      scientists besides Penn State, but it met with its destruction during
      the last hurricane that struck the island.

      One major experiment that I performed at Arecibo that paved a new
      direction for my research activities was to heat the ionosphere from
      the high-power wave interaction transmitter in an extremely low
      frequency mode that would modulate the natural current system flowing
      overhead of the antenna beam. This modulated current system was in
      effect an antenna, and it would radiate at this extremely low
      frequency (ELF); hence a wireless (one without wires) antenna was
      formed in the lower ionosphere. The importance of this result was
      that one could more easily generate ELF waves which would reach the
      lower depths of the sea to communicate with submarines. Obviously the
      Navy would have interest in this concept. My students that played an
      important role with this idea were Allshouse, Carroll, Lunnen, and
      Long, who were always accompanied by Tom Collins, who provided the
      real technical know-how to make these experiments a success.

      The Navy was funding the development of a new heater facility in
      Fairbanks, Alaska, since the current system was more intense and ELF
      generation could be much stronger and might find actual applications
      to Navy communications systems. The facility was operated by UCLA,
      but Penn State was awarded a large contract to make the facility
      produce data and to access the capabilities of this facility known as
      HIPAS (High Power Aurora Simulator) - first set up to cause man-made
      northern lights - but that was not feasible. We showed that one could
      almost always generate ELF signals, but the strength was strong
      during electrojet activity. We also showed that we could send digital
      data (although at a low baud rate) by phase shift keying the ELF
      carrier. Our mobile receiving van was out several hundred miles from
      the HIPAS source, and we managed to receive these ELF signals. An
      interesting experiment we did was to create two ionospheric antennas
      in the D-region spaced one-half wavelength apart and phased either
      180 degrees of 0 degrees in phase, creating what antenna experts
      would know as the end fire and broad side two element array. Our
      mobile van confirmed that we could make arrays of wireless antennas.
      Although two elements were the limit for the HIPAS facility, it did
      suggest that for a much larger facility one could perhaps construct a
      larger array of ELF elements and steer the beam of ELF radiation in
      desired directions. This was a first-time demonstration of this
      effect which could have bearing on future Navy system submarine
      communications, thanks to the efforts of Baker, Werner, Zain, Li,
      Sonsterby and Collins.

      Now to save space I will take some gigantic leaps in time to conclude
      this discussion. Realizing the importance of ELF generation and
      ionospheric heating in general, THE NAVY REQUESTED PROPOSALS FOR THE
      FEASIBILITY STUDY OF AN EVEN LARGER HEATER FACILITY; EFFECTIVE POWERS
      OF 10 GIGAWATTS OVER A LARGE RANGE OF HF FREQUENCIES WERE IN THE
      SPECIFICATIONS. At that time the antenna to handle this power and
      bandwidth and to be able to steer the heater beam in arbitrary
      directions was unknown. Penn State was one of three to be picked for
      the three-month feasibility study along with Raytheon and APTI (Arco
      Power Technology Inc.). Three months and $300,000 kept us up many
      nights, but we arrived at a rather unique facility of wide-band
      antenna and a modular approach to solid-state transmitters to meet
      the specs; I also recall we had suggested an underground control
      center that did raise eyebrows since environmentalists do like to
      disturb the permafrost. Our unique contribution involved the FIPA
      (frequency independent phased array) invented by Jim Breakall. It
      really solved most of the wide-band requirements. Unfortunately our
      antenna did not win since it was a new concept and the funding agency
      did not want to take on technological risk, but APTI did win with
      their straight forward array of closely spaced dipoles which later
      did cause some difficulty in "tuning" up the array. I said it was
      unfortunate that we did not win, but maybe we were fortunate for how
      could a University supervise such a large construction program from
      5000 miles distance? However, APTI, asked use to join them as
      subcontractor and design their antenna, which we gladly accepted.
      This work was done from ARL with the aid of Lunnen, Werner, Breakall,
      Groff and myself. We were successful, and we turned our design over
      to APTI; they began the construction and built several stages of the
      antenna and continue to expand the facility to its final design
      stage.

      My last few years at Penn State turned to different directions; I
      developed and taught a 400 level course on satellite communications,
      which was very popular and gave the students something they could use
      in the real world of industry. My research continued with industry
      support in antenna design but not for ionospheric heating
      experiments.
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