US2647989A - Flexible repeater - Google Patents

Description

Aug. 4, 1953 E. D. HILBURN FLEXIBLE REPEATER Filed July 17, 1950 tIDE 5530mm oh IPU INVENTOR EARL D. HILBURN 4/6 ATTORNEY Patented Aug. 4, 1953 UNITED STATES- PAT ENT OFFICE 1 Claim.

The present invention relates generally to wave energy repeaters, and more particularly to unattended wave energy repeaters which are capable of selectively re-directing waves without requiring the expenditure of energy.

In the art of television broadcasting, programs frequently originate outside the broadcast facility, such programs being known as on-thespot programs. When a program originates remotely from a broadcast facility, it is essential to transmit the program to the broadcast facility for broadcasting. It has been common to accomplish this by directional repeaters, operating at extremely high frequencies, but these have, in the past, been amplifying repeaters, and hence have been expensive to manufacture, and have required operating personnel and a source of electric power for their operation.

It is an object of the present invention to provide a directive repeater system which is completely flexible, and without restriction in respect to its receiving and transmitting directivity, economical of fabrication, which requires no attendance, involves no amplification of signals, requires no electric power for its operation, and which is highly eflicient, and dependable.

Briefly described, in accordance with the invention, video energy derived from a television camera, located remotely from a broadcasting facility, and having no clear line of sight thereto, is used to modulate in frequency a high frequency carrier, operating, say at 7000 me. This carrier is beamed to a dish or dish shaped collector, generally of parabolic cross-section, secured to a suitable elevated location, having clear line of sight both with respect to the transmitted carrier, and with respect to the broadcast facility. Energy collected by the dish is then applied to the input end of a hollow flexible wave guide, the output end of which applies the energy to a further dish or reflector, which transmits the energy to the broadcast facility. It is there picked up by a further directive antenna system, and the video signal derived by a demodulation process. The video energy so derived is then utilized to amplitude modulate a carrier in the television band, which is broadcast.

It is sometimes necessary to effect more than a single repetition of the frequency modulated energy, because of the relative locations of the video source and the broadcasting facility. This is entirely feasible, in the present system, because the repeating process is highly efiicient, at the frequencies involved, despite the fact that no amplification of energy takes place. Never- 2 theless, the repeated energy is at a lower level than is the energy received by the repeater, so that no problems of singing exist in the system. The relative orientations of the receiving and transmitting dishes of the repeater are therefore completely non-critical: .The use of a. flexible Wave guide to couple the dishes, further contributes to the extreme flexibility of the system, since each dish may be oriented in any direction, both in respect to elevation and azimuth, without any mechanical adjustment of the structures. In fact, it is this feature of completely flexible coupling of the receiving and transmitting dishes which forms the central inventive concept of the system, and which establishes its extreme practicability in actual operation.

The present invention, its objects, features and advantages will become apparent upon consideration of the following detailed description of a specific embodiment thereof, especially when taken in conjunction with the accompanying drawings wherein the single figure illustrates the invention schematically.

Referring now more particularly to the accompanying drawings the reference numeral I denotes a source of video frequency modulated carrier say at 7000 me.

The reference numeral 2 denotes a wave guide leading to a paraboloidal reflector 3, against which the wave energ supplied by the source I is applied by the button-hook 4, located with its exit at the focus of the paraboloid.

The reflector 3 directs a narrow beam 5 of Wave energy in the direction of its axis.

We may assume, for the sake of example, that the source of video frequency modulated carrier is vehicle mounted, or otherwise subject to variation of location, and that a broadcast facility 6 is so located that an obstacle, such as the building 1, is located between the source i and the facility 6, so that. direct transmission of signals is impossible. It is, in such cases, conventional to utilize a repeater suitably located to override the obstacle, and such repeater may be located on the roof of the obstacle 1, as at 8.

While the use of repeaters is generally understood, for the purposes outlined hereinabove, it has been conventional in the art toutilize an amplifying repeater. Such a repeater requires electric power, which is not always readily available, and must be maintained in adjustment, which requires personnel. Such repeaters are also subject to singing, so that the placement of the reflectors of the repeater to avoid singing is critical and diflicult. Further, no repeater system, except those utilizing frequency change, is available, which is capable of variation of reception and transmission directivity without difflculties of both a mechanical and an electrical nature.

It is one primary virtue of the present invention to require no power, which simplifies the structure of the repeater and renders it capable of installation anywhere. It is another advantageous feature of the invention that the same frequency that is received is transmitted, no frequency changes being required, and that singing is not possible since no amplifiers are employed.

The receiving and transmitting reflectors or dishes are orientable in azimuth and elevation and variable in spacing, completely independently of one another, so that reception may be accomplished from any direction, while transmission is occurring in any direction. Further, the repeater is reversible, and the spacing between its dishes may be any distance desired, within the limit of length of the wave guide coupling.

The above features and objectives are accomplished by joining lector or dish" 9, the axis of which is collinear with the axis of the reflector 3, to the transmitting reflector or dish Hi, the axis of which is collinear with the axis of an energy collector H at the broadcast facility, by means of a flexible wave guide H.

The receiving collector 9 is provided with a button-hook l3, consisting of a rigid extension of the flexible wave guide 12, the open end 14 of which is located at the focus of the paraboloidal collector 9, and with its open end directed toward the reflector. A similar structure is utilized at the reflector l0. Thereby, the repeater is reversible or bi-directional.

Since the button-hooks of the repeater apply energy into the reflector, and collect energy reflected from the reflector, it is customary in the art to define the antenna systems as reversely fed. The button-hooks may be rigidly secured to the collector or reflector structures, to assure that the openings thereof will remain at the focus of the paraboloids. The flexible wave guide I2 may then be detachably secured to the but ton-hooks, as by means of suitable flanges, or the like, so that the system assembled and assembled. The dishes may be mounted on camera tripods, CT, for ease of adjustment of directivity, or may be more permanently clamped to any available structure.- The camera tripods may each head 14, permitting orientation of the dishes 9, III, in azimuth and elevation.

The radiation pattern, both for reception and transmission, of the repeater system of the present invention, has an angle of divergence of about 2, so that the antennae must be very carefully aligned, if communication is to be established or maintained. Upon initial attempts at alignment of the system, further, it is impossible to determine which one of the several involved antennae are misaligned, since failure at any one antenna will disrupt the system.

To enable quick and efiective alignment of each the paraboloidal receiving colmay be readily disinclude an adjustable receiving and transmitting dish a boss [5 is provided, on the rearward surface of each dish through which extends an accurately machined aperture [6, precisely aligned with the axis of the dish. Into this aperture may be slidably inserted a suitable telescope l1. Alignment of the dishes may then be accomplished optically with assurance that when the complete system has been optically aligned communication may be effectively accomplished thereover, and any variation of position of the components of the system, and notably of the source I of video frequency modulated carrier, may be accurately and rapidly compensated for.

While I have described and illustrated specific forms of the invention it will be clear that variations thereof may be resorted to without departing from the true scope of the invention as defined in the appended claim.

What I claim and desire to secure by Patent of the United States is:

A radio repeater, comprising, a paraboloidal wave energy collector, a first tripod support for said collector, said support comprising means for adjustably supporting said collector for orientation at will in both azimuth and elevation, a paraboloidal wave energy reflector, a second tripod support for said reflector, said second support comprising means for adjustably supporting said reflector for orientation at will in both azimuth and elevation independently of said collector, a passive flexible wave guide section, a first passive rigid wave guide section rigidly secured to said collector and comprising an end opening aligned with the axis of symmetry of said collector for reversely deriving wave energy from said collector, a further passive rigid wave guide section rigidly secured to said reflector and comprising an end opening aligned with the axis of symmetry of said reflector for reversely applying energy to said reflector, means connecting said flexible Wave guide section in series with said rigid wave guide sections to provide a completely passive wave energy conduit between said openings, said collector having a mounting aperture extending parallel with the axis of symmetry of said collector, said reflector having a mounting aperture extending parallel with the axis of symmetry of said reflector, and a telescope within each of said apertures to enable visual alignment of said collector and reflector with a source and a receiver of ultra high frequency, respectively, whereby said repeater requires no source of power or means of wave energy amplification for its operation, and said reflector and collector are relatively adjustable independently in different orientations.

Letters EARL D. HILBURN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,028,866 Hansell Jan. 28, 1936 2,101,785 Wilckens Dec. 7, 1937 2,140,730 Batchelor Dec. 20, 1938 2,287,533 Peterson June 23, 1942

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