First-Hand:Ku Band Story
Ku Band Story
Submitted by Robert Walp
The first communication satellites used radio frequency bands allocated for terrestrial microwave systems which carried most domestic telecommunications traffic. This was partially because components at these frequencies already existed and partially because these frequency bands were available for commercial use, if not yet authorized for space to earth or earth to space use. The frequencies used were 500 Mhz portions of the spectrum at 4 GHz and 6 GHz. The letter designators are based on military codes for formerly secret radar frequencies. S Band is in the vicinity of 3 GHZ; Ku Band is from 12 to 15 GHZ, etc. Licensing requires both approval of the FCC as well as the ITU, a United Nations organization that coordinates use of radio frequencies and establishes other standards to ensure efficient global communications. Once it was decided that terrestrial and satellite systems could share the same C Band frequencies, earth to satellite transmission would be in the 6 GHz band and the down link would be at 4 GHz.
When different communications systems use the same frequencies at the same location a frequency coordination study must be made before licenses to construct and operate are issued by the FCC. This is to ensure that the signals from one system do not interfere with the other. In situations such as this, different portions of a frequency band may be allocated to different systems, but high capacity systems use all of the allocated bands, so that is not an option. Protection is also obtained by locating antennas so that objectionable amounts of energy from one system do not get into the other. Shielding can sometimes be provided by hills and even buildings. When satellites are used in the same vicinity and at the same frequencies as microwave systems there can also be interference.
The first communication satellite circuits were used in the international service where only a few links would be required. Very large earth stations, with antennas of the order of 30 meters diameter were standard. They had high power transmitters and sensitive receivers and could not be placed anywhere close to an existing microwave terminal. Seldom was that serious for these installations were very costly so that the added expense of building in isolated places was bearable. It could even be cheaper to put these five to ten million dollar stations in rural locations.
Frequency coordination gets much worse when there are many earth stations in a system, especially when they are located in urban areas. (Because there were no microwave facilities in rural Alaska, we had few coordination problems in our C Band system.) It became a problem when planning network television distribution because most studios and their transmitters are in urban areas and many of those had C Band microwave installations. Any future system to bring satellite signals into many urban location s just couldn’t use C Band.
I became curious over the Ku Band which was assigned for satellite use on an exclusive, not shared, use. Thus, Ku Band stations could be located anywhere without concern for terrestrial interference. There was no hardware at these frequencies. Worse, rain attenuation which absorbs all microwave radiation is much worse at the higher frequencies. It isn’t negligible at C-Band although heavy rain can cut signal strength in half. Responsible system design provides signal margins to ensure adequate signal strength for all bu a factional percentage of the time. At Ku Band, however, much greater attenuations are possible. This is affected by the length of the signal path through the rain which, in a satellite system depends upon the elevation angle of the rain, storm height and rain intensity which is a function of time and location. In the late 1960s the common feeling was that rain attenuation made use of the Ku Band impractical.
I gathered all of the rain data that I could find, to make some calculated estimates of the impact of rain at various places on earth over a year’s period. It didn’t seem as bad as everyone seemed to think. Further, there were other factors at Ku Band. The higher frequency produces a narrower beam for a given size antenna, meaning more transmit power density and more receive sensitivity. Signal to noise specifications for microwave systems require extremely high quality links because as many as 100 may be required for cross country transmission. Television engineers are sticklers for perfection and can detect degradation far before an average viewer could. And, I reasoned, it it’s raining so hard that one can’t see the television picture, one probably isn’t concerned about the television picture. I realize now that I was probably wrong. I did make a few simple tests and concluded that television signal quality could be far below existing specifications without serious picture impairment. I was sure Ku Band had a future.
Hughes agreed to do a study for Telesistima Mexicana, the Mexican television network, now Televisas, and prepare a proposal for satellite transmission of its programming throughout Mexico. I compared C Band and Ku Band systems, comparing total cost versus signal quality over the entire country. Ku Band was far superior and my report proposed a Ku Band system. I realized I wasn’t very well supervised because I didn’t learn I was expected to develop a C Band solution until the final draft was circulated for approval. I was told that we were selling off the shelf C Band satellites. I had to quickly throw together a C Band proposal that I was totally ashamed of. It truly made me ill and I considered resigning.
I was managing commercial satellite R & D expenditures and directed a small amount of money for the development of a Ku Band image enhanced mixer, a component needed for first rate satellite repeater performance. In a periodic R & D review in “Building One” before Pat Hyland, the gentleman who reported to Howard Hughes, and all other top executives, I got to my slides on the mixer, mentioning the potential of Ku Band. Dr. Albert “Bud” Wheelon, president of the Space Systems Division, told the audience that, “This is just a token effort, these frequencies will never have any commercial value.” Now I was sure I wasn’t adequately supervised. It’s good I wasn’t for I did have unbelievable freedom for a maverick. I had actually had very good mentoring from my boss, Don Worden for a while, but developed a terminal disease during this period, was preoccupied but not replaced for a long time.
At this time, probably in 1970, the Corporation for Public Broadcasting had decided to distribute its television programming by satellite. I was a member of the PSSC, the Public Services Satellite Consortium, established as a liaison between the technical and education communities. The PSSC was a forum for discussing CPB plans. I strongly urged that they use the Ku Band for it only made sense. The problem was that no one had put their foot in the water and nobody wanted to go first. (That is often a wise concern; let someone else do the beta test.) Further, Hughes, the leader, wasn’t supporting the Ku Band. So CPB selected the C Band.
One of the visitors to Hughes that was sent down to me was Colin Franklin, possibly head of the Canadian Communication Research Centre, CRC. He was planning CTS, the Communications Technology Satellite, to be built in Canada. At that time a C Band transponder was planned. I extolled the virtues of Ku Band and the need for test data on rain attenuation plus the possibility of using a very high power transmitter to work with tiny earth stations. He liked the concept so I took him to visit Hughes’ Microwave Tube Division, headed by Dr. John Mendel. There, he saw there would be no trouble in obtain a suitable traveling wave tube for the spacecraft transmitter. I had no further involvement, but the CTS flew with a 200-watt Ku Band transmitter. It was called HERMES and launched in January 1976. The satellite had two antennas which could be steered to place spot beams on widely separated locations. I proposed a demonstration intended to transfer documents at high speeds from the University of California Library to the University of Chile Library but it was rejected by the UC Board of Regents because they didn’t want to help Chile under he dictatorship of Salvador Allende. At least a Ku Band satellite had made it to orbit! Technical difficulties ended its lifetime prematurely, but it made valuable contributions to science and technology.
In late 1969, most likely, I was sitting at the bar of the Mayflower Hotel in Washington, DC. The person on the adjacent stool, John Johnson (probably?), said he was editor of a magazine named, Communications. He had a copy with a front cover color cartoon drawing of a fat, sloppy woman on her back in a boxing ring; the referee was holding up the arm of a young, scrawny kid. The heading said, “MCI knocks out Ma Bell!” The FCC had just ruled that MCI could build and operate a microwave system between Chicago and St. Louis. This was the first time competition in long distance service had been allowed. Johnson said that I ought to meet Jack Goeken, MCI’s founder because he liked Martinis, too. I later phoned Goeken and then met him. I talked about using a satellite link instead of building a terrestrial microwave system, which was moot because MCI had no money. I followed up on another trip to Washington, and another when Jack said I should talk to the new guy in the company who is getting financing. It turned out to be Bill McGowan, who brought money and took over as president. He was interested in the satellite concept and, as time passed, developed the concept of forming regional affiliates and tying them together with communication satellite links. Bill, Ken Cox, former FCC Commissioner hired by McGowan as legal counsel, and I had lunch several times and the concept of going directly to switching centers via Ku Band links took hold.
Bill and I thought Hughes and MCI might team up to build a nationwide system. I was not in marketing; I was a product line manager for small earth stations and these meetings were strictly informal, so I went to Paul Visher, who was a top-level staff member, possibly a vice president, who seemed to be somewhat of a master strategist. I told him of my meetings with McGowan and suggested that he call him. His reply was something to the effect that, “Contacts at this level are handled by me.” I was told to leave it to Visher. Some time later Bill called because he hadn’t hear from Visher. I called Visher who told me he was taking care of it. Bill called me again and said he couldn’t get through to Visher, himself. We concluded there wasn’t going to be a Hughs-MCI deal.
I called Joe Frietag who I worked with before he left for a satellite marketing job at TRW, one of our competitors. Joe did establish contact with McGowan and some discussions ensued. I had the vague hope that if MCI and TRW got together, there would be an interesting job for me. I believe there was a serious attempt to work out a business plan, but it didn’t succeed.
Bill told me he was securing rooftop leases in the big cities so he could be ready once he had a business arrangement. He asked me if I could put a group together that would be his nucleus for satellite planning. I checked with some friends; we decided what we would charge him and I sent him our resumes. They were Phil Rubin at Hughes, later to become Director of Science and Engineering at the Corporation for Public Broadcasting; Al Horley, at Stanford, who went to the Department of Health, Education and Welfare to help in the ATS-6 program; and Walter Hinchman, who had been Chief of the Common Carrier Bureau at the FCC and later consulted to Governor Egan in Alaska. Bill called from a hotel room one evening, said the package looked good and what would we cost? I told him. He said, “Just a minute, this TV is too loud.” When he came back to the phone he talked about something completely different. I concluded that we had priced ourselves out of the market and didn’t have the presence of mind to ask him about it.
In the meantime McGowan had worked out a successful arrangement with Lockheed Space Systems, forming MCI-Lockheed to construct a Ku Band system. He introduced me to his Lockheed counterpart with the idea that I would join Lockheed. I thought he was probably talking with me only to please Bill. Since I had no role in getting those firms together, I didn’t have a very strong position, nor feel very enthusiastic. Further, it would mean moving to Northern California, which wasn’t appealing at that time.
MCI-Lockheed filed with the FCC for a Ku Band satellite system in March 1971. Shortly thereafter a number of other companies filed for permission to operate satellites with Ku Band transponders. In late 1972, Comsat joined MCI-Lockheed, forming the CML Satellite Corporation. In July 1974 IBM filed an application to restructure CML by buying out MCI and Lockheed, leaving Comsat and IBM. (MCI had been installing microwave links and was becoming a mature company without satellites.) The plan was to supply digital services for business data processing. In February 1975 Aetna joined Comsat and IBM. The company was called Satellite Business Systems, SBS.
The SBS concept turned out to be misguided and poorly defined. There were stories of unrestrained spending and, once the satellites were in orbit, few business revenues. I would occasionally visit Bill and he would delight it telling me how recklessly they were consuming funds. Eventually SBS folded, IBM bought into MCI and gave them the satellites. On a subsequent visit to MCI I asked Bill if my version of the above story was accurate, or did he have a group that actually laid the groundwork for what became SBS. Bill said, “No, you were the only one. You’re the father of SBS and I’m eternally indebted to you, for we’re the only ones who made any money on it!”