US2138448A - Directional landing beam transmitter - Google Patents

Description

NW, 29, W33; A. GOTHE 2,133,448

DIRECTIONAL LANDING BEAM TRANSMITTER Filed Jan, 23, 1957 RNVENTOR ALBRECHT GOTHE ATTORNEY Patented Nov. 29, 1938 om'reo sm'r ss PATENT" OFFICE DIRECTIONAL LANDING BEAM ''rnANsMrr,-

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tion of Germany Application January 23, 1937, Serial No. 121,961

In Germany January 6, 1936 1 4 Claims.

The present invention relates to a transmitter arrangement for guiding airplanes when making a blind landing.

It is known that with an energized antenna :and one or two keyed reflectors, directive radio beams can be produced. Short waves are propa gated of the order of 7 meters. Dipoles of approximately .\/2 length are usually employed as primary radiators and as reflectors. These dipoles are set up at such height above ground that the lower dipole ends have a distance of several meters from the ground. Thus the entire arrangement assumes a comparatively great height. Beacons as commonly constructed for radiating the 7-meter waves usually have a total height of 10 to 12 meters above ground. Installations of such a height create a serious disturbance especially in the vicinity of the airports.

According to the invention the course lines therefore are produced with low antennas of approximately A/ l in length while retaining the radiation diagram, said antennas are arranged above a surface (sheet metal or wire mesh) having favorable conductivity i. e. the property of reflecting electrical waves. In this way, the radiation diagram of the antenna arrangements hitherto in use, is substantially retained, while the total height of the arrangement is only a fraction of the hitherto ordinary arrangements.

The distance of the reflectors from the exciter antenna can be chosen less than l/ l. At proper tuning of the reflectors, a suflicient sharpness of the course lines is then obtained. 7

In order to avoid losses, i. e. to obtain a favor- 35 able efiiciency, antennas and reflectors are formed of freely supported rods or tubes which do not require auxiliary supporting means or tensioning means. Considerable losses are caused in the known guide ray antennas particularly 40 by auxiliary supports and tensioning means and especially when the atmosphere is humid.

In order still further to decrease the height of the arrangement, the antennas and the reflectors may be chosen still shorter than )\/4,

5 and may be provided with concentric-point extension means such as balls, plates or rings.

The tuning of the reflectors for the production of sharply focussed course lines. is carried out preferably at the base point by means of con- 50 densers which, in order not to weaken the radiation, may be arranged underneath the conducing surface.

Instead of two reflectors alternately functioning either as an absorption pole, or as a re- 55 fiector, a single reflector may be used which,

through corresponding tuning at the base point thereof, is tuned alternately to a wave that is longer or shorter than the operating wave thus acting in theone case as a reflector and in the other case as an absorbing antenna.

The antenna may be fed through a transmitter arranged at the base point of the antenna or by means of a'remote transmitter whose energy is fed to the antenna through concentric conductors. In the latter case the line is suitably laid out under ground while the conducting surface is placed directly on the ground.

My invention will be further described by reference to the accompanying drawing in which Figure 1 shows one embodiment having an energized antenna and a pair of reflecting antennas which are alternately tuned to the wave length to be propagated, and

Fig. 2 shows a modification of the invention in which an energized antenna and only one reflecting antenna are shown.

In Fig. 1 the exciter antenna I having the length V4 is fed from a transmitter, not shown in the drawing, across the condenser 4 and the energy line 6. The antenna i extends at right angle to the conducting surface 3 on which the two reflector antennas 2, 2 are disposed at a distance of V4 or less. The lower end of each reflector wire is connected to the plate 3 across one or the other of the tuning condensers 5. The switches l9 are inserted in these connection lines for periodically alternating the action of one reflector with that of the other.

Fig. 2 shows a similar arrangement in which only one reflector is used. There is disposed on the metal plate 9 (wire mesh) in the vertical direction the radiator 1 having an extension capacity l6 and which is still shorter than M4. The antenna is fed across the condenser II and line H]. In parallel to the exciter antenna and within a suitable distance thereto the reflector wire 8 with point capacity I5 is disposed. The base of this reflector can be connected alternately across the condensers l3 and M to the plate 9 by means of the switch l2, so that it is tuned alternately to a wave that is longer or shorter than the operating wave.

Through the arrangement of antenna and reflectors on a conducting reflection surface the entire assembly is substantially independent of its surroundings. The idea of the invention is in no way limited to the examples shown, and it can be expanded in any desired manner.

For instance, it will not be necessary to set up the arrangement directly on the ground surface, but the beam antenna may also be mounted on the roof of a building or on a special tower.

I claim:

1. In a directional landing beam transmitter a vertical antenna having a maximum length of M4, a source of. energy coupled to said antenna, means including a vertically disposed reflecting antenna system for rendering the wave emitted by the first said antenna directional, means including a plurality of horizontally disposed reflectors positioned adjacent the base of the first said antenna for intensifying the directional effect of said wave, a plurality of capacitive coupling means, and means for interposing separate ones of said coupling means alternately between said reflecting antenna system and one of said horizontal refiectors,.respectively, thereby to vary the directional characteristic of said wave,

2. An ultra-short wave antenna system having a plurality of vertically disposed radiators, each radiator having an efiective length substantially equal to M4, where A is the length of the Wave to be radiated, said radiators being spaced apart by a maximum distance of 7\/4, means for directly energizing one-only of said radiators while causing one other of said radiators to function as a reflector, a metallic reflecting surface horizontally disposed at the base of said radiators, means for capacitively coupling a certain portion at least of said reflecting surface to at least one of said radiators, and switching means for periodically and alternately connecting different vertical radiators and different portions of said coupling means into circuit relation with said reflecting surface, thereby to key the variations of directional eiTect produced by said reflecting surface in coupled relation to difierent ones of said radiators.

3. A system in accordance with claim 2 and including an energy feed line connected to one of said vertical radiators, said feed line being disposed beneath said horizontal surface.

4. An ultra-short wave antenna system having a pluralityof vertically disposed radiators, each radiator having an effective length substantially equal to M4, where x is the length of the wave to be radiated, said radiators being spaced apart by a maximum distance M4, means for energizing one only of said radiators and means for selecting and causing a different one only of said radiators to function as a tuned reflector, the last said means comprising a horizontal reflecting surface and a capacitor coupling the same to said selected radiator.

ALBRECHT GOTHE.

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