US2238261A

US2238261A - Radio beacon system

Info

Publication number: US2238261A
Application number: US209973A
Authority: US
Inventors: Hahnemann Walter Max
Original assignee: Standard Elektrik Lorenz AG
Current assignee: Alcatel Lucent Deutschland AG; C Lorenz AG
Priority date: 1937-05-25
Filing date: 1938-05-25
Publication date: 1941-04-15
Anticipated expiration: 1958-04-15
Also published as: NL55627C; FR838403A; CH204547A; GB502302A

Description

April 1943 w. M. HAHNEMANN 2,238,261

RADIO BEACON SYSTEM Filed May 25, 1938 2 Sheets-Sheet l INVENTOR. Ira/fer Max //a/$/7e070/7/7 BY ATTORNEY.

April 15, 1941.

W. M. HAHNE MANN RADIO B EACON SYSTEM Filed May 25, 1938 2 Sheets-Sheet 2 Ire (an r1904 6274477470/P5 Patented Apr. 15, 1941 barren stares ram orrio RADKO BEACON SYSTEM Application May 25, 1938, Serial No. 209,973 In Germany May 25, 1937 Claims.

The present invention relates to radio beacons adapted to produce guiding course lines for vehicles and the like, and consists in certain features of novelty explained in the following description and pointed out in the appended claims, reference being made to the accompanying drawings in which- Fig. 1 is a diagrammatical representation of the radiation pattern obtained by radio beacon transmitters adapted to produce a straight course line; Fig. 2 is a diagram showing radiation patterns for obtaining a bent course line; Fig. 3 shows a plurality of course lines produced according to the invention; while Fig. 4 is a plan explanatory for the invention, and Fig. 5 shows diagrammatically an arrangement of a transmitting beacon in accordance with my invention.

Radio beacon arrangements are known which produce guiding course lines by the utility of one radiating antenna which is continuously fed by a high frequency generator and two reflecting means which are alternately keyed in such manner that one reflector is effective during the ineflectiveness of the other reflector. The line of equal field intensity thus obtained represents the guiding course line. This condition is illustrated in Fig. l by way of an example. The radiating dipole D is continuously fed by a high frequency generator which is modulated with a predetermined tone-frequency. The reflectors RI and R2 are alternately keyed in accordance with the dash-dot, or the A-N-rhythm in such manner that one reflector is rendered effective whilst the second reflector is rendered inefiective. The two radiation patterns AI and A2 are thus alternately produced, and the two guiding lines L! and L2 are obtained by comparison between the amplitudes of the keyed signals of different kind. In cases that the system presents symmetric structure, the two guiding lines LI and L2 form one single straight line. It is also possible to provide any optional angular relation between the two guiding lines LI and L2 by deliberately unbalancing the aforesaid symmetry which may be accomplished by exciting the two reflectors out of phase which expedient permits the radiation to be directed at will toward any desired point or position.

The Fig. 2 shows the last mentioned arrangement, according to which the radiating dipole is continuously supplied and the reflecting means RI and R2 are alternately rendered effective and as to obtain the desired unsymmetry of the radiation patterns AI and A2 relative to each other. The straight 180 degree relation between the two guiding lines LI and L2 is then replaced by an obtuse angle.

The radiation of more than two guiding course lines from one single point is frequently required. This problem is solved according to the present invention by providing a radio beacon system which permits any desired number of course lines to be radiated over an antenna system using one single transmitter only. The novel system comprises one continuously fed radiating dipole D adapted to cooperate with any desired number of reflector sets RI, R2, and RI, RE which are alternately rendered effective. According to a further feature of the invention either a particular keying frequency, or a dis tinctive high frequency or even tone-frequency is allotted to each set of reflectors for the purpose of distinguisl'iingv the" separate course lines thus produced. The direction of the individual course lines is determined by correspondingly adjusting the phases at which. the reflectors are excited by any known means.

The operation of the new system according to the invention is hereinafter moreprecisely disclosed in conjunction with one embodiment shown in Fig. 3, and the structural diagram of Fig. 5', which by way of an example illustrates an arrangement for producing four dilferent course lines. A radiating dipole D is continuously fed from a high frequency generator TR. Two reflecting means RI and R2 forming one set of reflectors are allotted to said dipole. A further set. of reflectors independent of the first mentioned set and comprising the reflecting means RI and R2 is also allotted to the radiatinefiective exactly in the manner heretofore described. The phases of the reflector exciting voltages may be adjusted at any desired rate so obtained, that is, one system comprising the radiating dipole D and theireflecting means RI and R2, and a'second" system likewise comprising said dipoleD and also-the.- reflecting means RI and R2. In cases that the flrst'mentioned system, i. e. D, RI and R2,.v is rendered effective, the directive diagrams AI and A2 and thus the course-lines LI and L2 are obtained, while the effectiveness of the second system, that is, D, RI and R2, produces the directive diagrams A! and" A2 and the resulting-course lines LI and L2. These two' system are alternately rendered operative by known means-such as switching device U, and a switch SI,.;in such manner that one system transmits over a period of one minute, for example, during which interval the sec ond system remains inactive, whereupon the second system operates for one minute, in which time the first mentioned system remains ineffective.

It has been proposed according to one feature of the present invention for the purpose of distinguishing from one another the different course lines produced by the two alternately effective systems to allot' thereto either distinctive high frequencies, that is, various wavelengths, or distinctive modulation frequencies, i. e. specific characterization tones, or even different keying frequencies, but the simultaneous utility of more than one of the above mentioned markings of distinction is also within the scope of this in-, vention. The discrimination between the separate course lines is effected in the receiving position and this will be accomplished in connection with the first mentioned method by accordingly tuning the high-frequency portion of the receiver, while on applying the second expedient this distinction is performed by chains of filters forming part of the low-frequency portion of the receiver. The corresponding discrimination in cases of employing the last mentioned method is accomplished in a simple manner by means of acoustic comparison.

It has already been pointed out in the foregoing that the particular advantage involved by the present invention consists in the possibility of producing a plurality of course lines by means of one single high frequency transmitter. In order to obtain the aforementioned course line distinction, a switching equipment U is provided for cooperation with said transmitter, this equipment being adaptedto alternately apply thereto either different high frequency oscillations, or different modulation frequencies from generators Ml, M2, or different keying frequencies from generator G. Moreover, additional switching means S! are provided which during the effectiveness of one reflector system render the remaining systems ineffective. This measure may suitably be effectuated by making theswitching equipment of the transmitter dependent upon the switching means which during the operation of one reflector system render all remaining systems inoperative. A conjoint cam-controlled device may, for example, be used for this operation. 1

According to still another feature of the invention, the separate reflecting means of reflector systems transiently in state of rest are not necessarily to be rendered ineffective during the operation of one particular reflector system. Onthe contrary, individualreflecting means may be maintained effective so as to assist in producing the necessary directive characteristics for obtaining radiation toward a given direction.

. In connection with the embodiment shown in Fig. 3 it should be observed that the dash-dotted circular radiation pattern of the radiating dipole D during ineffectiveness of the reflectors is dimensioned so as to intersect all points of inter-' section between the entire number of directive characteristics, in order to secure keying free of crash noises.

An arrangement of the new radio beacon sys-'- tem is illustrated in Fig. 5 in which there is shown a radiating dipole D which is continu ously fed from the high frequency transmitter Tr over the feeder line L. At either side of the dipole D there are provided the reflectors RI and R2 which together form a continuous guiding system. Further reflectors RI and R2 transmitter;

which likewise form a second continuous guiding system are located at a given angle to the first mentioned system RI, R2. Each of the reflectors includes keying means Kl, K2 and Kl, K2, respectively. The keying means KI and K2 on the one hand and the keying means KI and K2 on the other hand are coupled with one another and are controlled over the line LI and L2, respectively, from the device G which generates a keying frequency. A switching device U has for its object to alternately render effective the reflector-systems RI, R2, and RI, R2, respectively, for which purpose a switch SI is mechanically coupledwith the switching device U. The switch SI in. one position causes keying means Kl, K2 of the reflector system RI and R2 to be controlled over the line Ll from keying device G, while in the other position the keying means Kl, K2 of reflector system RI, R2 are controlled over line L2 from G. If asymmetric patterns are desired, as shown in Figs. 2 and 3, such patterns may readily be secured by adjusting the phases of excitation of the reflectors in any known manner. If, for example, these reflectors are parasitic reflectors as shown in Fig. 5, central inductance F may be adjusted to effect such tuning, asis usual in the so-called Lorenz" type system. A further switch S2 which is adapted to cooperate with the aforementioned switch S1 serves for changing keying frequency being produced by the generator G so that a different keying frequency is used on the separate course lines. This may be accomplished in any known manner, e. g. by varying the release time'of relays if the keying device G is of the relay interrupter type or by varying the speed of rotation of a motor if this generator G is of the motor driven cam controlled type. Finally, a third switch S3 likewise mechanically coupled with the switching device U and the aforementioned two switches has for its object to alternately apply the means Ml and-=M2 to the high frequency transmitter Tr. These means MI and M2 may be tone frequency generators producing different tone frequencies by means of which the transmitter Tr is modulated in dependency upon the position of the switches. On the other hand, the means MI and M2 may be devices adapted to change the carrier frequency of the transmitter Tr, that is, the wavelength produced by said For example, devices MI and M2 may be carrier frequency sources of different frequency for supplying different carrier frequencies to transmitter Tr.

The invention is by no means restricted to the arrangement for producing four guiding course lines as described in conjunction with Figs. 3 and 5. On the contrary, any desired number of reflector systems as above described may be allotted to a radiating dipole so as to produce six, eight, ten or more guiding course lines. A given distinction such as a predetermined wavelength modulating frequency or keying frequency is to be allotted to each course line. Y Geographical and -atmospheric conditions frequently obstruct'the possibility for employing a throughout straight course" line between two air ports, in which cases; it will be necessary to proing grounds, for example. In order to obtain a guiding course line which corresponds to the route in question, and in accordance with still a further feature of the invention, individual guiding ray transmitters of the type above described are located at the points or landing grounds 0 and D for producing radiations having the desired angular relation to one another. The angle of radiation from each transmitter is adjustable by accordingly selecting the relative phases for keying the appertaining reflectors.

What is claimed is: p

1. A radio beacon transmitter system comprising a radiating dipole antenna, a high frequency generator for continuously feeding said antenna, a plurality of reflecting means arranged about said dipole and combined to form several individual reflector systems for providing separate angularly related guiding course lines, and means for rendering said reflector systems alternately eifective and ineffective.

2. A radio beacon transmitter system as defined in claim 1, further comprising means for transmitting a difierent given high frequency from said dipole for each of said alternately efiective reflector systems.

3. A radio beacon transmitter system as defined in claim 1, further comprising means for providing a different specific modulating tonefrequency to said generator for each of said alternately effective reflector systems.

4. A radio beacon transmitter system as defined in claim 1, further comprising means for switching a different particular keying frequency to control each of said alternately effective reflector systems.

5. A radio beacon transmitter system comprising a high frequency generator, a radiating dipole continuously fed by said high frequency generator and adapted to produce a circular radiating pattern, a plurality of reflecting means arranged about said dipole and to form several individual angularly related reflector systems, means for rendering said reflector systems alternately effective and ineffective for producing separate angularly related guiding course lines, and means for allotting to each of said alternately efiective reflector systems a distinguishing signal characteristic.

WALTER MAX HAHNEMANN.