Oral-History:Edwin Douglas Ramsay Shearman
About Edwin Douglas Ramsay Shearman
The interview starts with how Edwin Douglas Ramsay Shearman's interest in radio began. Shearman became interested in radio when his grandfather gave him a 1-valve radio, and this interest was further developed in college. He was educated at Imperial College, where the City and Guilds Engineering College was part, and took a degree in electrical engineering. While in college, Shearman attended a lecture at the Radio Society given by the Director of the Post Office Research Station at Dollis Hill and was fascinated by it. He also participated in Home Guard activities. In 1945, Shearman got his first job in the UK Scientific Civil Service, based at Admiralty Signal Establishment (ASE). Later, he was employed as a Scientific Officer in the Department of Scientific and Industrial Research (DSIR) and went to the Radio Research Station at Slough. Since that period, he had been engaged for fourteen years in research on ionospheric sounding, design of vertical sounders, ground backscatter sounding and its application to frequency management in broadcasting and aeromobile radiotelephony, and satellite topside sounding and space research. His work at DSIR was also tied up with the Soviet Sputnik I launch.
In 1962, Shearman made a complete change to his career and entered the University of Birmingham. He was appointed Senior Lecturer in Electromagnetism at Birmingham and engaged in setting up the Radio Research Group. In 1965, he was appointed Professor and later Head of the Postgraduate School in the Department of Electronic and Electrical Engineering. He built up his own research program on a Moon-bounce project, and a number of professors and leaders in industry and government research stemmed from the program. Shearman also carried out a research project at Birmingham—on over-the-horizon radar and remote sensing—with the backing of the UK Scientific Research Council and others from 1975 through 1990. The project was to do research on tilts in the ionosphere, and originated from his earlier work at Slough in the 1950s when new techniques for measuring ocean waves remotely were developed. With the success of the project, Shearman was invited in 1982 to give the first Open Lecture of the International Union of Radio Science (URSI) at Washington DC on the subject. In addition, he was awarded the Institute of Electrical Engineers' Faraday Medal in 1986 and the IEEE's Fellowship in 1982, specifically for this project.
Ramsay Shearman has carried out many activities beyond research: he was appointed to the UK Ministry of Defence Electronics Research Council and was a Chairman of its Antennas and Propagation Committee. He became Deputy Chief Scientific Officer as an honorary member of staff of the Royal Signals and Radar Establishment. Moreover, Shearman was involved in helping various government panels and committees. He worked along with international organizations, including the North Atlantic Treaty Organization (NATO), the Royal Society Committee for Radio Science which linked in with the International Union of Radio Science (URSI), and the Electronic Engineering Association.
At the end of the interview, Ramsay Shearman tells about his hobbies and spare-time activities after retirement.
About the Interview
EDWIN DOUGLAS RAMSAY SHEARMAN: An Interview Conducted by Peter Hill of the Communications Chapter, London, England, IEEE History Center, 16 August 2006
Interview #467 for the IEEE History Center, The Institute of Electrical and Electronics Engineers, Inc.
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It is recommended that this oral history be cited as follows:
Edwin Douglas Ramsay Shearman, Electrical Engineer, an oral history conducted in 2006 by Peter Hill, IEEE History Center, Piscataway, NJ, USA.
Interview: Professor Edwin Douglas Ramsay Shearman
Interviewer: Peter Hill – IEEE UK&RI Section, Communications Chapter, London, England
Date: 16 August 2006
Place: Great Malvern, England
School and Early Interest in Radio
Please tell us something about your school career and how you got to be interested in radio during school and beyond.
My interest in radio originally started when I was at school in Bedford and my grandfather gave me a 1-valve radio. It became more serious when I was at King's College School at Wimbledon where they had an annual hobbies exhibition. One of the students gave me the circuit diagram of a 1-valve shortwave radio to make myself, which I did. From there I went eventually to a 7-valve superheterodyne and listened to the fascinating shortwave broadcasts around the world. I couldn't transmit at that time because it was wartime, but I was able to tour the world via shortwave radio.
Those were very exciting days. The Battle of Britain was in process. I heard an RAF “Red Leader” giving his Flight companions attack instructions by radio telephone. At that time one walked out and saw the vapor trails of British and German aircraft overhead and the Spitfires doing victory rolls over the school on their way back from combat. I always thought that one of them that came over was probably an ex-student of the school who was showing off at his old college. We were once bombed in the back garden where I lived and once in the street in front. Hiding in the cupboard under the stairs was quite a common thing when the bombs fell. In the school training corps we had a slightly out-of-date version of Army field radio sets. Thus, I got to know something about the way the Army did things and got a background of interest in defense electronics from that time.
University and Vacation Work
Now perhaps we can talk about your University education and how you did there, including vacation work and beyond.
In 1942 I went directly from school to Imperial College — the City and Guilds Engineering College was my part of it. I took a degree in electrical engineering, in the final year concentrating in ‘light electrical engineering’, as communications was called in those days. The government was very anxious at that time to guide people into microwaves and radar, so there was an admixture of microwaves in the last year. However, before I got to the final year, I attended a lecture at the Radio Society given by the Director of the Post Office Research Station at Dollis Hill. He talked about the possibilities of undersea cable telephony. I found that fascinating.
I was studying during daytime and in the evenings I was learning about Mills Bombs, mortars and so on in the Home Guard. Then I was posted to an antiaircraft rocket battery in Battersea Park. These Home Guard activities were mixed up with learning and a number of us appeared in uniform at the University when attending the lectures.
An important feature of an engineering degree then was vacation (out-of-term) work in industry. I went to the Post Office Research Station at Dollis Hill. I worked in the Physics Laboratory there under Arnold Lynch, who had a distinguished career then and later. Another project he was working on was a high-speed five-hole paper tape reader with photocells, and there was a small-scale production line re-capping RCA photocells in the laboratory. Somebody whispered to me that this was something to do with coding. Actually it was not; it was to do with decoding. Dr. Arnold Lynch developed the photo-electric paper-tape reader, which was an essential part in the ‘Colossus’, the first electronic computing machine, though I did not discover this until decades later when the decoding of the German Enigma-Machine code at Bletchley Park was revealed.
My summer vacation of 1944 was spent at Marconi's Wireless Telegraph Company at Hackbridge in Surrey. This was some distance from where I lived near Wimbledon. The journey by bus over that period was with the glass windows of the buses with lace curtains glued to them as a protection against shattering by blast. During the flying-bomb raids this journey was rather an anxious time. When we heard the motorbike noise of the flying bomb going overhead we listened for the engine stopping, and immediately ducked, knowing that the dive into the ground was starting, and waited for the bang.
Was that the V1?
Yes, that was the V1. I was a ‘snagsman’ at Marconi's. That is the man who finds what the faults are in transmitters and receivers. The transmitter on which I worked was the T1154. That was extensively used – you will have seen photographs of it in the wartime bombers – but it was actually developed for the pre-war flying boats. (I was fortunate to travel in a flying boat later). The receiver was the R1155, which had an automatic landing indicator with two crossing needles. This receiver is still used by amateurs for listening to shortwave radio, even today.
One day in my final year at Imperial College we were fairly high up in the building in South Kensington and I was listening to a lecture on Fourier analysis by Mr. Urwin. This was a time when the V2 rockets were landing. When you heard the explosion of a V2 rocket, it had missed you, creating an immediate sense of relief. One then heard the thunder-like noise of the rocket coming towards you faster than sound; the bang first and then the noise of the turbulent wake. I remember that one of these things went off during Urwin's lecture while he was talking about transients. After the bang happened he said, "For instance, that is a transient. If that had been going on all the time you wouldn't have noticed it. It's the fact that it has a sudden beginning and end that distinguishes it." I thought that was a remarkable exhibition of ‘cool’.
We've got to the point where you left University and went for your first job which, as I understand it, was in the UK Scientific Civil Service, initially based at Admiralty Signal Establishment (ASE) in 1945.
Yes. I received a letter from the Director of the ASE, Lythe Hill House at Haslemere, commanding me to report on a particular day in October, 1945, which I did. I found an English country mansion with buses constantly arriving and leaving, which in the Navy they called ferries, with sailors, civilians and Wrens (WRNS – Womens Royal Naval Service). This was the active research centre of the Admiralty. It had moved back from Portsmouth to avoid coastal bombardment.
I was directed from ASE at Lythe Hill House to HMS Flowerdown near Winchester in Hampshire. This was not a ship; it was a shore establishment of HF (High-Frequency 3-30 MHz or shortwave) receivers, HF-receiving antennas and receiving antenna switchboards, but the Navy only knew about ships to they called it ‘HMS’ (His Majesty’s Ship). There were some fifty receivers in each room. Wrens and civilians were receiving signals with this equipment. The task I was involved in was to introduce radio-teleprinters into naval ship-shore and shore-to-shore HF communication. The station's main task before this had been the interception of German and Japanese Morse traffic for decoding by Bletchley Park. We found techniques such as ‘radio fingerprinting’ and analysis of the received signal used in this work to be very useful for our task of analyzing ionospheric echo distortion and fading as it affected inter-symbol interference on radio teleprinter signals. In this period I was involved at HMS Flowerdown with developing receiving techniques, primarily in order to get radio teleprinter signals over a fading, multipath shortwave link. We had to use diversity, and we had large, three-receiver installations connected to three different spaced antennas, providing triple-diversity reception. In this way we could connect a radio teleprinter directly to the digital output of the diversity receiver and our digital signals (then known as ‘Mark’ and ‘Space’, rather than ‘1’ and ‘0’) went up the line to the underground communications center under the Admiralty Arch in London.
I was also employed to work on high-power transmitters at Horsea Island transmitting station in Portsmouth Harbor. This experience was invaluable to me, as I was later heavily involved with high-power communication and radar transmitters and I was already familiar with the safety techniques to work on these, like making sure everything was switched off before opening the doors and then keeping one hand in my trouser pocket and discharging capacitors safely with an earthing rod.
The whole experience of working on shortwave communication with transmitters, receivers and beginning to understand the vagaries of the ionosphere I found to be invaluable to me in later years as I became involved in research and teaching in HF and later in microwaves and laser communication. The sort of experiences I was getting at that time were directly relevant to mobile radio problems and fiber communication and optical communication through the atmosphere in which I was involved until I retired some fifty years later.
My next post was to employ the same techniques, but for the Royal Navy taking over from the U.S. Navy its transmitting and receiving stations at Londonderry. This was when the U.S. Navy was very active in Europe and Londonderry was the communications hub. There were some interesting problems for me to think about in Londonderry. I became interested in the different system of diversity used by the U.S. Navy. Instead of using triple diversity as we had, they used dual diversity, just two spaced antennas, and frequency-shift keying which they thought provided enough diversity that the third aerial was not necessary. That made me think a bit about these systems. The idea of frequency-shift keying instead of on-off keying stayed with me for a long time. It was something I looked into later when I became active in university research. I also became familiar with American ways of dealing with things and worked with the U.S. Navy personnel. In the end the U.S. Navy decided that the Cold War was coming along and they decided not to leave Londonderry after all.
While I was at Londonderry another task arose. I was asked to come back to London and was briefed on a new project, which was ship-shore and shore-to-shore communication with radio teleprinters. This was for the royal voyage of King George VI and Queen Elizabeth to South Africa in 1946-47. I was asked to go to Cape Town because the link out to Cape Town had a much poorer performance than the link from Cape Town back to home and yet this was going to be crucial for press coverage and the logistics of the royal visit to South Africa.
I set out to South Africa, stopping in Cairo for three days, my first encounter with the Ancient Egyptian and Arab World. Then I flew by flying boat (which used the transmitter and receiver that I had worked on at Marconi's). I went on an ordinary civil passage to Durban from Cairo, landing at all the flying boat stations up the Nile and Lake Victoria and down the East Coast of Africa to Durban, with three night-stops on the way. It was a fascinating experience. Flying at 30,000 feet in a 747 is of no interest compared to that experience of flying low over Africa and seeing the game, Mt Kenya, Mt Killimanjiro and the Great Lakes.
I discovered the reasons for the poor performance of the radio link. The reasons were technological rather than propagation, associated with the fact that no one who was really sufficiently technically competent was responsible for the maintenance there. I was able to bring the performance to South Africa up to the level of the return path, and that was very satisfying.
I learned a lot about propagation during that period. It's a difficult thing to do research on a shortwave link – or it was at that time – because the communication to the other end consisted of messages that were sent at closing time. There was no speaker line with which to experiment and everything was a bit formal in arranging modifications and changes and so on. I learned about that technique but I also learned about the ionosphere and how it behaved in South Africa as opposed to the UK and problems of going over the Equator. Atmospheric noise was a big problem down in Cape Town, so there were many useful experiences there. Then a colleague of mine and I went to Scarborough, another interception station of wartime days, to monitor the transmissions from HMS Vanguard as it steamed South from UK to Capetown. It was a successful project and I learned something of interception techniques as well as radio communication when I was at Scarborough.
Department of Scientific and Industrial Research
Work with Arnold Wilkins
Then you changed employers and went to work for the Department of Scientific and Industrial Research (DSIR). Perhaps we could hear something about that and your reasons for changing and moving into DSR.
The employment at the Admiralty Signal Establishment was really my military service. I was a civilian but this was like other services that people did in peacetime in that period. I was a temporary civil servant up to that time, a Temporary Experimental Officer. Those of us who wanted to stay in the Scientific Civil Service entered a competition for entry. I was successful in being employed as a Scientific Officer in the Department of Scientific and Industrial Research, the DSIR, and I went to the Radio Research Station at Slough. That was the beginning of fourteen years of research on ionospheric sounding, design of vertical sounders, ground backscatter sounding and its application to frequency management in broadcasting and aeromobile radiotelephony, ending up with satellite topside sounding and space research. It was invaluable experience in antennas and propagation. I was working under general supervision but as an independent researcher at that time, amongst people I could learn from. My supervisor in this work was Arnold Wilkins who was the coworker of Sir Robert Watson-Watt and who in 1935 set up the first experiment on detection of aircraft by radio in the UK. Watson-Watt also founded the Chain Home, the chain of radar stations around the UK that were the crucial aid to successful employment of fighter aircraft intercepting German bomber raids in the Battle of Britain.
My initial work was concerned with design of ionospheric sounding equipment, so my background in transmitters was useful there. Then Wilkins introduced me to a special ionospheric sounder that had been developed during the war by Marconi's as a prototype but had never been ordered in quantity. It had a power of 10 kW. This, when connected to a suitable aerial, could receive backscatter from the ground, and was more power than was usual in ionospheric sounding at that time. Instead of only sounding the height of the ionosphere straight above it, it could then go on to receive signals backscattered from the ground beyond skip distance, so-called backscatter. I was encouraged to experiment with this and discovered a very interesting phenomenon that had not appeared in the literature at that time - there was a linear relationship between the time delay of the earliest backscatter to be received and the transmitted frequency. Frequency could be plotted horizontally, range of the echoes vertically and the result was a straight line tangential to the range curve of the second-bounce vertical incidence reflection from the ionosphere. This was quite an exciting discovery and experiments based on it confirmed that the backscatter was in fact coming from the ground and not from the E layer, as the Marconi scientist, T.E. Eckersley had asserted. I then went on to study how backscatter could be used as a guide to aid the choice of the best frequency for communication to a particular location on the Earth's surface.
Wilkins' direct contact with the Chain Home and all the technology that had been developed during the war in radar was invaluable in this work. Wilkins was able to acquire a high-power transmitter MB2 (Mobile Based type 2) using two output tetrode valves with cathode emissions of 70 amps and with a a high-voltage supply of up to 30,000 volts. With this, we had available a much higher power than the Marconi device I mentioned earlier. I developed one of these transmitters to tune continuously using a variable inductor from about 5 to 25 MHz with an output power of 150 kW, a very valuable research tool. We developed directional antennas, a rotating antenna and a plan position indicator display so that one could depict the contour of the skip distance that surrounded the radar station and monitor what the ionosphere was doing over an area the size of Europe and beyond.
Wilkins also arranged the loan of a complete Chain Home radar station at Fraserbugh in Scotland. I was tasked with getting this to go in the HF band below 20 MHz. A very interesting sudden emergency arose at that time. I had just succeeded in getting this transmitter to produce about 400 kW at 15 MHz when there was a telephone call from Wilkins. Watson-Watt had had his attention drawn to the fact that if one used vertical polarization in ground-wave mode at HF, one should be able to get radar echoes from low-flying aircraft over sea at much greater ranges than was possible with a microwave radio. I was instructed to modify the transmitter back to 22 MHz, which I did, while a colleague designed and built suitable vertically polarized antennas. Then we had visits from US Air Force, RAF and Industry. We set up experiments with an RAF aircraft – a Mosquito I remember – American jet fighters and the first American 4-jet Bomber. We demonstrated satisfactorily that one could detect low-flying aircraft by this so-called ‘ground wave radar’ out to much greater ranges than microwaves permitted.
This was another period when I had all sorts of scientific problems and possibilities drawn to my attention. I was very interested in the fading properties of sea clutter. Wilkins said ‘You don’t get sea clutter at these frequencies’, but he was thinking of the horizontal polarization used in the Chain Home. Vertical polarization had revealed sea clutter coming from long ranges. This faded, and the fading turned out to have an extraordinary potential as a mine for data, which became evident later. I was also intrigued by the fact that when an aircraft was going through this sea clutter, you could see the location of the aircraft by a sort of fluttering pulse when it was considerably lower in amplitude than the clutter and noise. Also, turning attention to the noise, one could calibrate a receiver, turning the signal generator down until it was well below noise, and by putting a meter on the output of the receiver, one could detect that there was a difference between the output voltage when the carrier was there and when it was not. This ‘post-detector integration’ and ‘signal processing’ business opened up a whole field of research for me later, but this was where the possibilities first came to light.
International Geophysical Year
I believe now, Ramsay, you would like to talk about the International Geophysical Year (IGY) and your further work at DSIR which led to some of your professional works tied up with the Soviet Sputnik I launch.
Yes. The launch into orbit of Sputnik I as a part of the IGY provided anyone with a shortwave receiver the ability to tune into a frequency just adjacent to the well-known U.S. Bureau of Standards 20-MHz time and frequency transmission and hear the Sputnik's characteristic ‘bleeps’. The radio-scientific community and the general public were fascinated with this first revelation of the Space Age. Simple measurements of the Doppler shift, the changing direction, the regular fading pattern (which proved to be connected with the Earth's magnetic field) and the occultation of the signals by the Earth yielded exciting new scientific information about the orbit and the ionosphere not previously available. Dr. Hugh Hopkins, whose specialty was direction-finding and who appeared to have received an early warning through the scientific community, alerted some of us to congregate at Ditton Park, Slough, on Saturday the 5th and Sunday the 6th of October, 1957, after launch late in the evening on the 4th.
We had an Adcock HF direction finder, angle of elevation measuring equipment and receivers, tape recorders, a Rohde and Schwartz frequency-synthesizer and a telephone-timing channel from Royal Aircraft Establishment, Farnborough, all of which were pressed into service.
We managed to produce some interesting data, and a little later took part in a discussion meeting held by the Institution of Electrical Engineers in London, which acted as a focus for a number of organizations in the UK that had made observations at this time. All this information was put together and subsequently published. There were people from Jodrell Bank describing the detection of the echo from the rocket by radar and Dr James Hey describing microwave tracking of the rocket at the Royal Signals and Radar Establishment, Malvern. Numerous others described measurements of the characteristics of the transmissions from the satellites as received at the ground.
This was a very exciting meeting, and a related visit was also very memorable. Hugh Hopkins, William Bain, myself and a number of others went up to Cambridge University to meet the radio astronomers and ionospheric physicists at the Cavendish Laboratory. Everyone was excited by the possibilities – the things that could be observed and the inferences that could be made. That was really my introduction into space research, in which I became quite heavily involved later.
Work in Ottawa
In 1960 I believe you went to Ottawa for six months. You worked there for some time — perhaps you would like to tell us something about that.
The impact of space research on the Radio Research Station was very marked. It became the Radio and Space Research Station and later, when Ratcliffe came as Director, it became the Appleton Laboratory and was centered very largely on space research. I was asked to go to Ottawa to join the Canadian group developing the Alouette Topside Sounder Satellite. This was using my skills in sounding of the ionosphere from the Earth's surface and helping the Canadian team to build one in a satellite to look down on the top of the ionosphere and identify its ‘topside’, not visible by sounders on the ground. This was with the satellite surveying the whole of the Earth as the satellite orbited the Earth and the Earth rotated within the orbit.
This period in Canada was very exciting and I joined a very enthusiastic and active team in Ottawa. My own particular responsibility was for the tubular pole antennas, which unfurled like a carpenter’s steel tape when the satellite was established in orbit. Two of these at right angles, one 75 ft tip-to-tip and one 150 ft each centred on the satellite were used for the ionospheric sounder to cover the HF frequency band. It was necessary to have a decametric-sized antenna for the decametric wavelengths covered. I was also responsible for the telemetry with which the Appleton Laboratory were to be involved, providing telemetry stations in the Falkland Islands, Singapore and in the UK. I became a member of the National Aeronautics and Space Administration (NASA) working group. I attended working group meetings regularly in Washington, Boulder Colorado, New York and Ottawa for the six months I was in Canada and then for the next eighteen months or so after I had returned to the UK. It was a very successful experiment, spawning a hundred scientific papers in the year or two after the launch and mapping the topside ionosphere over the Earth.
You went back to Slough to rejoin DSIR and Ratcliffe in space research and ionospheric studies.
Yes. I became involved in the quite large program of satellite and rocket experiments that Ratcliffe was evolving. I was also involved in assessing the ionospheric scatter technique, in which a microwave radar is pointed straight up through the atmosphere to get the weak scattered echoes from the E layer, F layer and exosphere for analysis. That was quite an active period of research, but only some eighteen months in duration until I left to join the University.
I believe you want to discuss a little bit more about your space research at Slough before we talk about entering the University of Birmingham.
Yes. I really wanted to make some comments about Ratcliffe as a research leader. He was a Fellow of the Royal Society and came from the Cavendish Laboratory at Cambridge University where he had learnt his skills with Ernest Rutherford and J.J. Thomson in the great days of nuclear physics before the war. He built up a world-famous ionospheric research group back at the Cavendish after World War II, and played a crucial role in setting up Ryle's Radio Astronomy Group, which of course also became world-famous. During World War II, Ratcliffe was for a time in charge of half of the scientific manpower of the Telecommunications Research Establishment (TRE) at Malvern with the vital post-production task of getting new radar equipment into service with the RAF. I learned much from Ratcliffe about the methods and organization of research. A comment made about him has been "his devastating efficiency," but that gives a rather machine-like description to a very human person who enjoyed doing research with fellow workers.
University of Birmingham
Now we've gotten to the point of 1962 when to some degree you made a complete change of career and entered academe at the University of Birmingham. Can we hear please about your career change there and perhaps the motivation for going into academic work compared with working at a research establishment?
It was a time of dramatic change for me. I had become unhappy chopping and changing between one task and another in the civil service. In my visits to universities in England and the USA when I was on the topside sounder job, I had been attracted by the freedom to choose and follow one's own research themes which university life made possible. I focused on Birmingham because I had my attention drawn to a job there, but also because I had been following the research publications by Professor Gordon Tucker and his group at Birmingham, which were very akin to my own interests – halfway between the technology and the application to the study of the environment. His studies were in sonar rather than radar but there is a great deal in common as you know.
I had also become more attracted to teaching, which is a great clarifier of the mind. Telling other people about things highlights any shortcomings of your own knowledge. I always used to think that one does research and believes, "Now I've got it cracked. I want to go and tell the students about this" and then lectures on it. However, one finds that perhaps one didn't know quite as much as one thought, goes back with questions in mind and does more research, goes forth to preach this new doctrine, and then discovers again that it's not the complete picture. This interaction between teaching and research is vital, and I think it's the duty of academics and researchers outside to underline this and not let the administrators cut all the research out and make people teach through their vacations and this sort of thing. Those things were motivations.
I was appointed Senior Lecturer in Electromagnetism at Birmingham, and then with the encouragement of Gordon Tucker I set up the Radio Research Group. In 1965 I was appointed Professor and later Head of the Postgraduate School in the Department of Electronic and Electrical Engineering as it then became. I have very happy memories of creative research discussions in the Staff Tea Room and in Departmental Colloquia at Birmingham – especially after the examinations in June when three months of uninterrupted research with students and other staff were before us. We used to bounce ideas for new work off each other at these sessions. These would be tried out first as undergraduate final-year projects or as three-month projects for Master’s Course students in the Summer. If they were promising, we would progress to full-scale funded research activities for students and research staff. It was a very exciting and companionable environment in which to work.
I believe at Birmingham, Ramsay, you were so successful at research and postgraduate work that they put you in charge of the Birmingham Postgraduate School. Please tell me something about that.
Perhaps I can illustrate that by explaining how I built up my own research program. I was interested in communication over radio links with multipath and fading – Doppler spreading – which was an interest stemming from my days in Naval Communications before I was at Slough. With two research students, a technician and hardware scrounged from friends in defense research, I set up a microwave Moon-bounce link as a test bed. The Moon, as observed from the Earth, appears to rock backwards and forwards, so that some of the mountains are approaching and others receding, so that echoes from them are Doppler spread. Also there are echoes from mountains on the Moon at different ranges from the observer, which give range-spreading. There is thus a fading, multipath environment, and yet the transmitter and receiver are in one place with a common antenna, time-shared for transmission and reception, making it a very suitable test-bed. A 2.5 second message can be dispatched into the Earth-Moon space before the echo begins to arrive back. I set up this microwave Moon- bounce link in real hardware with one student, but another student built a model which consisted of a rotating rough spherical ‘Moon’ model immersed in a water tank with sonar transducers representing the Earth-located radio transmitter and receiver. The idea was to test out adaptive multipath-correcting modulation schemes. This Moon-bounce project led to an interest in satellite communication and in antenna design, which was a growth area during that period. Several students followed this career with distinction.
I was counting the total number of professors that came out of this work and its successors, and the sum I got was ten, which isn't too bad. A number of leaders in industry and government research also stemmed from this work. When we moved later to a new building there was a certain amount of money available for new projects with it, and we took the opportunity to design and equip a 6-meter offset Cassegrain reflector antenna on the roof of the building. It was quite an architectural item. We used it to make radiometric measurements of the urban microwave environment. This was of interest to people who wanted to set up satellite communication terminals in cities like London or Birmingham, and also to the post office, as they had microwave links extending over the country. The antenna was also used with a 10-GHz radar to map out the reflectivity of the terrain and buildings and with the use of Doppler techniques to pick out moving vehicles.
On a personal level, I was discovering at this time how to apply modern spectral analysis techniques to radar and communication systems as well as educating myself and hopefully students in vector analysis as applied to electromagnetics and antennas. It was a great pleasure a few years ago to meet a past undergraduate stemming back from that time when he told me my lectures on electromagnetics oriented his career in that direction. There are some satisfactions in university teaching.
Radar and Remote Sensing Research
Now I believe you want to expand on your research activities, and in particular the first area is over-the-horizon radar and remote sensing.
When I left the Radio Research Station, now renamed the Appleton Laboratory, I set aside the study of high-frequency (HF) radio propagation and the physics of ionospherically propagated ground backscatter, now known as sky-wave backscatter. However, I knew there were questions left that needed improved experimental techniques and new theoretical approaches in order to be answered. I thought this move to the University would perhaps enable me to get back to these questions. In the 1950s I was perhaps the first person to publish the analysis of sky-wave backscatter using the radar equation together with a simple model for the scatterers on the Earth's surface. This model was very crude but consisted of hemispherical bosses dotted about on the surface. I showed that the observed signal strength of the backscatter could be produced if these bosses were only about 6 feet high and were dotted about every hundred feet or so. In this way, it was not necessary to have an outrageous angularity in the scatterers to get the sort of amplitude that was observed. This contradicted what T. L. Eckersley, the Marconi engineer, had said earlier when he identified these scatterers as being in the E region. My earlier work on the linear relationship between the earliest range of the backscatter and the frequency transmitted showed that the ranges we were finding corresponded to the Earth's surface and this new computation showed that the irregularities were of the right sort of order.
Later I became involved in experimental measurements for the Royal Aircraft Establishment (RAE) of the spectrum of ground-backscattered echoes. Radar engineers of course called this ground-return or sea-return ‘clutter’, though in the remote sensing field we came to realize this so-called ‘clutter’ was valuable. It's a goldmine really. These measurements revealed that the spectral bandwidth was small and that it would be possible to detect the Doppler-shifted aircraft echoes – which had Doppler-shifts of 10 Hz or so – and possibly also from ships at ranges of thousands of kilometers in the presence of stronger terrain or sea echo. A small university group such as ours would have problems in making such a radar to experiment with. The size of the antenna array needed to achieve useful angular resolution was rather frightening. To obtain a 1degree angular resolution at 17 MHz required an aperture of about a kilometer with some 120 monopole antennas spaced 8 meters apart. That sort of money is not lying around in some miscellaneous petty-cash fund in a university department. In like circumstances Rutherford is quoted as saying, "We haven't any money, so we have to think".
This led us to use the 2-antenna aperture synthesis technique pioneered at Cambridge for radio astronomy and adapt it to radar by using a frequency-jittered transmission to make the echoes from different directions incoherent – like radio stars that the radio astronomers watch. This is not quite the same as the synthetic aperture technique used in aircraft where one relies on the coherence of the echoes. We first demonstrated that this scheme worked in a water tank using ultrasonics and optical signal processing – which was interesting to learn at firsthand – and then by scrounging a petrol-driven railway repair trolley from British Rail when they shut down the Bridgnorth line. We equipped the trolley with a Yagi antenna and uncoiled a coaxial cable as it traveled along a straight railway track. This railway track was borrowed from RSRE Malvern, where it was used for radio astronomy work. We were able to demonstrate high-resolution mapping of stratified ‘sporadic E’ clouds over Europe by observing the ground backscatter propagated by way of reflection from these clouds and resolving the angles by the synthetic aperture technique.
Around this time an HF backscatter radar installation set up by the direction-finding community for remote identification of tilts in the ionosphere became available. The Birmingham group was encouraged to do research on this. The reason the direction-finding people were interested was because direction finders could be made as accurate as desired with good technology, but one could still get the wrong answer for the direction of the received signal if the ionosphere were tilted in the middle – especially at dawn and dusk. The scheme was to use radar echoes from the ground to determine what the distant ionosphere was doing that caused this tilt. We carried on with this research. The installation was in an old airfield in Gloucestershire and consisted of forty-nine wide-band antenna elements in front of a reflector curtain 300 meters wide and a 100-kW tunable pulse transmitter, making it a very flexible remote sensing installation. It also had the interesting feature that one set of forty-nine elements was situated to the east of the reflector curtain and another set to the west. In this way we had a beam-forming antenna that could slew a beam over some 90 degrees looking to the east or to the west, enabling us to look at land backscatter and sea backscatter. We equipped this with Doppler radar so we could analyze the spectrum of the land and sea echo from Europe and the North Atlantic. We showed that this made it possible to identify coastlines by the difference in the echo spectrum of land and sea.
Perhaps it might be worth going back a bit to my earlier work at Slough in the 1950s. I noticed a phenomenon when Earth's surface backscatter was observed by way of widespread stable sporadic E clouds. (These are thin horizontal sheet-like ionized clouds, very akin to the stable inversion layers in the troposphere that produce mirage effects). The sea echo faded with a period on the order of 1 or 2 seconds whereas the land echo was steady for tens of seconds. This was by sky wave. Going back to my time on the Chain Home station at Fraserbugh, I had noticed a somewhat similar effect on the ground-wave-propagated sea echo – except that the land echo did not fade at all whereas the sea echo bounced up and down in a period of 1 or 2 seconds. At that time I thought, "There are some possibilities here" and buried this away in my memory. In 1955 a letter was published in the journal Nature by D. D. Crombie of New Zealand showing that there was a simple relationship between the frequency of the fading, the wavelength of the radio wave and the wavelength of the ocean waves – which were matched in a simple way to the radio wavelength being used. He pointed out that this opened the door to a whole new technique for measuring ocean waves remotely. Crombie, when he later went to the United States Central Radio Propagation Laboratories (CRPL) at Boulder, Colorado, told me that he was very unhappy that this lovely idea, when it was published in the scientific literature “fell like a lead balloon”. However, after the theoretical work done by Klaus Hasselmann at Hamburg, Donald Barrick at CRPL and Lucy Wyatt in my group at Birmingham and also after experimental work done in the United States, United Kingdom, Australia, France and Canada, the technique has yielded a greater resource for remotely sensed ocean data than Crombie ever imagined.
Wave-height, wave-spectrum, wave-direction, surface-current, surface wind-direction and wind-speed can all be determined as well as the speed and direction of moving ships. Fixed and transportable HF sea-state radars have become a valuable part of the oceanographer's armament since that time. It was this project that occupied my group at Birmingham, with the backing of the UK Science Research Council and others, from 1975 through 1990 and thereafter by Lucy Wyatt in her new appointment as Professor at Sheffield University.
I was invited to give the first Open Lecture of the International Union of Radio Science (URSI) at Washington DC in 1982 on the subject. The Institute of Electrical Engineers’ Faraday Medal in 1986 and the IEEE’s awarding of a Fellowship in 1982 both specifically mentioned this work and were sources of great pleasure to me.
Professional Activities Beyond Research
Panels and Committees
I believe you want to tell us something of the activities beyond research, because they certainly do impact on how research is carried out and all the wider issues of research organizations.
Yes. I think perhaps an example might be a good way of starting this. I was appointed to the Communications Committee of the Science Research Council. This is a grant-awarding body, but it also tries to stimulate research in particular areas. As members of this we were having a discussion about which fields of activity should be encouraged. I was putting forth the case of mobile radio as being a growth area. Many people hung to the old idea of mobile radio for police and fire, with dedicated networks — wider networks were just becoming to come forward. I had demonstrated with David Parsons, a new member of our staff, that in fact research on mobile radio could be done with quite small resources. About the only thing really needed was a van to fill with equipment. We got in touch with the police in the Birmingham area and cooperated with the University of Bath (Professor William Gosling) and the University of Bradford (Professor David Howson), who was a former Birmingham member of staff. The Chairman of the SRC Committee was very supportive of this initiative and later Gosling, Howson and I put forward a proposal for a ‘University's Mobile Radio Consortium’. In fact I think we started this informally and then put the proposal forward for SRC encouragement. This was very strongly encouraged and I think it was the beginning of the close cooperation of university electrical engineering departments.
Being a professor at Birmingham, obviously you were called in to help various government panels and committees. Can we please hear a little bit more about those?
Yes. I was appointed to the UK Ministry of Defence Electronics Research Council (a sizable organization) and I was Chairman of its Antennas and Propagation Committee. I was also made an honorary member of staff of the Royal Signals and Radar Establishment - I think Deputy Chief Scientific Officer was the title. These contacts and the opportunity to learn and contribute by visits to research establishments and firms were a particular feature of this work. The same is true of the Royal Academy of Engineering of which I was subsequently elected a Fellow.
Of course there must be an international dimension to your committee work and technical activities.
My first experiences were through the North Atlantic Treaty Organization (NATO) AGARD panel. It's a curious sort of name, but it was the ‘Advisory Group on Aerospace Research and Development’, as I remember. This organized conferences to which people were invited, and I went to a series of very good conferences. The first one was at the University of Cambridge with Ratcliffe as the Chairman. That was the first time I ever heard his brilliant skills in summing up the conclusions of the conference and putting the whole thing in context. You met people who were working not necessarily for defense but most often they had contacts with their national defense organization. Other people came who were all specialists in the area being discussed and presented papers. The discussions afterwards were very lively, and meetings were held after the conference as well. We always had tours through local fields of interest and so on. I remember forming quite a close relationship with a French engineer from the University of Paris and getting on quite well with him speaking French and me speaking English. Neither of us knew really enough to speak in the other person's language, but it worked very well.
Kind of pidgin English and pidgin French?
Yes. Another meeting was in Norway which was specifically about remote sensing of the Earth's environment using HF techniques. I was able to contribute our work on the synthetic aperture radar that we built at that time. Other meetings were at Oberammagau in Germany, again on remote-sensing. One very memorable AGARD meeting was at Lindau in the Harz Mountains of Germany, which was a Max Planck Research Institute, set up for the study of the ionosphere, extended to the whole of the atmosphere later. We saw the work that was going on at the Institute at that time and I met all sorts of people there who were working in parallel fields, and it was useful in building up contacts.
I was also co-opted onto the Royal Society Committee for Radio Science, a national committee that linked in with the International Union of Radio Science (URSI), an international body that held a very big conference every three years lasting a week, of which I attended a number. Perhaps one of the most memorable was in Prague after the Berlin Wall came down. People from Poland, Czechoslovakia and Russia were there together with Western delegates. This was an absolutely super conference, and of course Prague was the place to visit before anybody went on package tours there. URSI was a very live organization, different from AGARD where the conferences were by invitation. One could apply to read a paper at URSI and seek support from one's national committee for help with the travel to get to the conference. I have been to URSI conferences in London, San Francisco, Washington, Tel Aviv and Prague. They particularly encourage young scientific workers, and this is a great boon, allowing them grants to attend these conferences. When I was in Prague for instance I shared accommodation with a New Zealand worker who was reading his paper on radio astronomy. He obviously found the experience very valuable indeed.
Another national organization I became involved with back in the 1960s was the Electronic Engineering Association. This is a community of firms in the UK radio communication and radar industry. They wanted to stimulate further training and education of new graduates before they went into the radio communication and radar industries. We were invited to launch a ‘Bosworth Course. G.S Bosworth chaired the Ministry of Technology committee which originally proposed this idea. At Birmingham we launched the Bosworth course on Radio, Communication and Radar. It was very successful, even though it consisted of two different sorts of structures that were not altogether good bedfellows. We ran one-year MSc courses, where students were sponsored by firms with Science Research Council support. Students spent the first two terms at the university and then went back to their own firms where they did individual projects and university staff went to visit them. They came back for higher-level specialized courses in radio communication and radar. Then all the students went off to one particular firm and did a group project together.
Mervyn Morgan of Marconi's, who was one of the great drivers of this scheme, was very unhappy about the university project organization. He considered that it trained people to work as individuals whereas the industry wanted people to work in groups. The university staff learned a lot, as did the industrial staff - the banging of heads together was an excellent thing. We got to know individuals in all the varieties of the industry by going out and supervising students and getting to know the industrial staff that supervised them. A number of lecturers came from industry and gave specialized lectures in the summer term. It served to knit together University and Industry in a way that had been done for some time with government research organizations but not sufficiently with industry. This was a very good and fruitful thing.
The other part of the organization was that the specialized courses were grouped together into concentrated periods of two or three weeks. People came from firms and from the Navy, Army, Air Force and research establishments and attended just these modules. What they wanted was as many notes as they could get, the idea of the thing, and then they wanted to carry all this stuff back to their firms and use bits of it as they wanted. They were cherry picking. What our full-year students wanted was to get the overall view of the courses we were giving and then pass exams at the end and put in a good project report. I gave papers at conferences on organizing this mixture of short- and long-term courses, and it was quite tricky but we managed it.
“Retirement” and Hobbies
Now you are retired, but of course like most senior academics you are not really retired at all. Maybe you could give us a few words about what you do now in your so-called spare time.
In the first few years after I retired from Birmingham I continued my association with RSRE Malvern – QinetiQ, as it later became – and they were kind enough to give me the Mathematica program so that I was able to do propagation analysis for them. I found this a stimulating connection with the group there and honed my skills and upgraded my computer to a faster speed and more storage and coupled it into the Internet and so on. I try to keep up to date. However in more recent years, particularly as QinetiQ is not quite tuned or organized in the way that the government research establishments I used to work with, I don't find myself working with them as happily as before. I have become more interested in history – the history of electronics, radio and radar. I have written articles on these subjects and given lectures, an activity which keeps me alive technically. I am also able to cut down a bit the great stock of files and papers that I previously kept.
What about hobbies and activities?
As one does at my age, I am trying to keep myself fit by walking. I am very fond of music and I go to the concerts of the English String Orchestra, which is located in Malvern, and other concerts. I follow the efforts of my granddaughter to learn the piano and encourage it. My wife and I follow the interests of two of our daughters respectively as a Museum Conservator and Art Gallery Curator. I have always been a practical person, an engineer rather than a theoretician, and when my wife and I moved down here to Malvern I did not initially favor the idea of living in a flat (an apartment). We are located for this interview in our original upstairs flat in which we keep a study and accommodation for visiting grandchildren, while we live in the main flat beneath it. Naturally I have wired the flat downstairs to the flat upstairs for Internet and telephones and whatnot. Part of the bathroom was originally designed by the builder to be a dressing room. I have converted that into a miniature workshop and there is a bench there and a drilling machine and all the tools with which one wants to make things, repair my wife’s antiques and fix things when they go wrong. Those are the sorts of activities in which I get involved now.
Thank you, Professor Shearman, for giving us your oral history.