United States Patent (19) 11 4,378,558 Lunden 45 Mar. 29, 1983 54 ENDFIRE ANTENNA ARRAYS EXCITED BY PROXIMITY COUPLNG TO SENGLE WIRE FOREIGN PATENT DOCUMENTS TRANSMISSION LINE 146804 3/1959 U.S.S.R. .............................. 343/785 OTHER PUBLICATIONS (75) Irventor: Clarence D. Lunden, Federal Way, Wash. "Antennas," Lamont V. Blake, John Wiley & Sons, pp. 196-201, 230-233,248-251. Assignee: The Boeing Company, Seattle, Wash. "Antenna Fundamentals,' pp. 24-29. (73) Jasik, Henry, Ed.; Antenna Engineering Handbook; 1961; pp. 16-34 through 16-36, 16-40 through 16-41, (21) Appl. No.: 174,453 16-56 and 16-57. 22 Filed: Aug. 1, 1980 Primary Examiner-Eli Lieberman Attorney, Agent, or Firm-Christensen, O'Connor, (51) Int. Cli.............................................. H01O 1/28 Johnson & Kindness 52) U.S. C. ................................... 343/814; 34.3/785; 57 ABSTRACT 343/DIG. 2; 333/240 (58) Field of Search ....................... 343/785, 895, 771; A lightweight, efficient, microwave power transmitting 333/240 antenna is disclosed, suitable for use in a space borne transmitter for beaming solar generated electrical power down to earth based receiving antennas. The 56) References Cited space borne antenna structure is formed by modules U.S. PATENT DOCUMENTS that are structurally integrated into a multimodule an 2,130,675 9/1938 Peterson .............................. 343/81 tenna array. Each module comprises a rectangular 2,192,532 3/1940 Katzin ................................. 34.3/8 framework of limited depth having rigid sides circum 2,624,003 12/1952 ams .................................... 343/771 scribing a generally open region in which a plurality of 2,685,068 A954 Goubau ................................. 333/95 spaced parallel single wire Goubau transmission lines 2,688,732 9/1954 Kock ..................................... 333/95 are strung to create a "see-through' harp-like configu 2,921,277 1/1960 Goubau ....... ... 33.3/240 ration. A Klystron powered feed wave guide is dis 2,929,065 3/1960 Kreinheder . 343/785 2,993,205 7/1961 Cooper ................................ 333/240 posed as one structural side of the module for exciting 3,002,189 10/196 Butler ...... ... 343/793 standing electromagnetic waves on the plurality of 3,136,996 6/1964 Parker ................................. 343106 Goubau lines. Printed circuit Yagi end fire radiators are 3,155,975 1/1964 Chatelain . ... 34.3/785 supported on dielectric webs disposed in juxtaposition 3,219,954. 1 1/1965 Rutelli................................... 333/95 with the Goubau lines for being synchronously excited 3,283,330 A1966 Chatelain . ... 343/785 by the standing waves on such lines. The modular, open 3,328,800 6/1967 Aigeo .............. 343/771 framework construction together with the use of single 3,373,434 3/1968 Lorenzo et al. .................... 34.3/895 wire Goubau transmission lines for exciting the web 3,392,396 7/1968 Ehrenspeck ... ... 34.3/755 mounted Yagi radiators, forms an exceptionally light 3,509,572 3/1970 Barbano .......... ... 343/792.5 3,541,568 1/1970 Lowenhar ........................... 343A877 weight structure which when disassembled can be con 3,77,077 1 1/1973 Tischer ........ ... 333/95 S solidated in a high density package for being launched 3,811,633 5/1974 Cummings et al. ... 242/54 A into orbit, and then subsequently assembled in space. 3,935,576 1/1976 Pickles ................ ... 34376 4,278,955 7/1981 Lunden ................................. 333/33 22 Claims, 8 Drawing Figures AZ272/ aa222 572/72A62 s 3. U.S. Patent Mar. 29, 1983 Sheet 1 of 3 4,378,558 s U.S. Patent Mar. 29, 1983 Sheet 2 of 3 4,378,558 U.S. Patent Mar. 29, 1983 Sheet 3 of 3 4,378,558 s 2227ZZzy re -- s 4,378,558 1. 2 useable amounts of electrical power to earth. Because of ENDFIRE ANTENNA ARRAYS EXCTED BY this generally planar configuration of the antenna struc PROXIMITY COUPLNG TO SNGLE WIRE ture, it is not practical to launch an assembled antenna TRANSMISSION LINE into orbit; rather, the constituent elements for the an tenna arrays must be consolidated in high density pay BACKGROUND OF THE INVENTION load packages and launched in this form into space and The invention relates to antenna arrays of the type in assembled by crews while in a stable orbit. This require which the radiating elements are excited by proximity ment places a severe constraint on the nature and shape coupling to a source of electromagnetic surface waves of the ultimate structure, and more especially on the developed on an adjacent conductive structure. 10 components that are used to assemble the final struc While the invention broadly concerns antenna arrays ture. Also, the weight-to-power capability of the an having the foregoing characteristics, a preferred form tenna arrays becomes an important factor and desirably of the invention, as disclosed herein, is deployed as a this ratio is held to a minimum so that each launched space borne, earth directed beam antenna for transmit payload package has that much greater value in terms ting solar-to-electrical converted power earthward for 15 of transmitting power versus cost capacity. collection by ground based receiving antennas. Preliminary studies show that a six-foot by six-foot It has previously been proposed that solar power can array of rafted, slotted wave guides may have an earth be efficiently converted to electrical power at space weight in the neighborhood of 120 to 160 lbs. For over borne satellites and then transmitted to earth in the form all efficiency of the satellite power station, it has been of microwave electromagnetic energy, which as used 20 estimated that the total weight for an antenna module herein refers to the higher frequencies of the radio band, having a comparable level of power transmitting capa such as from about 300 megahertz to 4,000 megahertz. bility, should be around 20 lbs., far less than the pro By collecting solar energy in large surface area arrays jected weight of the previously proposed antenna struc of solar cells located in orbit above earth's atmosphere, ture. a significantly greater degree of the available solar en 25 ergy can be captured and transformed into electrical In addition to the above factors, a practical antenna power than is possible using earth based solar cells. array for this purpose must have a high degree of rigid After the solar-to-electrical power conversion how ity in order to obtain phase stability needed for power ever, it becomes necessary to provide means for effi transmission efficiency. All elements of an antenna ciently transmitting the electrical power to earth. For 30 array must have a predetermined, constant phase rela this purpose, it has been proposed that the satellite tionship in order to produce a predictable and stable set structures that support the arrays of solar cells be of propagating wave fronts which constructively com adapted to mount high frequency transmitting equip bine to form the directional characteristics of a beam. If ment for transforming the solar-derived electrical excessive expansion, contraction, twisting, or other power into high frequency electromagnetic energy and 35 deformation of the antenna structure occurs in reaction for beaming such energy earthward to ground based to the environmental conditions in space, such as the receiving antennas. At frequencies suitable for transmit above-mentioned solar pressure, then certain sections of ting relatively large amounts of power through the the array will exhibit phase shifts with respect to other atmosphere, antenna structures in the microwave band elements, thereby reducing the overall beam-forming are considered most effective. 40 capability of the array. One proposed transmit antenna structure for this Accordingly, it is one object of the invention to pro purpose comprises rafts of juxtaposed microwave vide an antenna array suitable for use as the transmit guides, each of rectangular cross section and slotted antenna in a solar driven satellite power station, in along the larger dimension face of each wave guide, in which the electrical and structural characteristics of the a known manner, for collectively radiating a highly 45 array overcome one or more of the foregoing disadvan directional beam of radiated electromagnetic energy. tages or difficulties associated with previously proposed By creating large planar arrays of such rafted wave configurations. guides, a relatively efficient transmit antenna can be Another object of the invention is to provide an an created. While such an antenna configuration is feasible, tenna array for such a space power station that con there are certain disadvantages inherent in its structure bines electrical and mechanical properties to yield a which would be desirable to overcome or avoid. First, novel antenna structure characterized by a high degree the slotted wave guide raft configuration when assem of transmit efficiency and beam forming phase stability bled in space, results in a relatively heavy, bulky struc when arrayed in a generally planar structure that ex ture. Additionally, the nature of the component wave tends over the large area needed to transmit useful lev guides are such that the structure is highly susceptible 55 els of electrical power earthward. to overheating due to the combined efforts of resistive Still a further object of the invention is to provide a losses in the structure during the transmission of power, novel antenna structure for microwave frequencies and due to the interception of solar energy as a result of which is characterized by being relatively light in the closed face configuration inherent in its architec weight, having an open lattice structure that is substan tute. 60 tially transparent to solar heat, and being sufficiently Furthermore, there has not been a satisfactory pro rigid so as to achieve a high degree of phase stability. posal for arranging the components in a high density An additional object of the invention is to provide a package for being launched into satellite orbit for as modular antenna structure for use in a space power sembly in space.