US2189283A - Beacon aerial - Google Patents

Description

Feb. 6, 1940. ANZ 2,189,283

BEACON AERIAL Filed Dec. 31, 1937 INVENTOR Kai/Q7" FHA/V2 vigm ATTORNEY Patented Feb. 6, 1940 UNITE STATES BEACON AERIAL Kurt Franz, Berlin, Germany, assignor to Telefunken Gesellschaft fiir Drahtlose Telegraphic m. b. H., Berlin, Germany, a corporation of Germany Application December 31, 1937, Serial No. 182,675 In Germany December 22, 1936 7 Claims. (01. 25o-1-11 This invention deals with the reduction-of the horizontal component of field in the radio beacon course of a radio range.

The problem arises quite frequently in practice where beacon aerials have to be erected upon metallic surfaces of finite dimensions. For instance, theproblem may consist in erecting or rigging up a radio range aerial upon the roof or top of a vehicle or to build a radio range equipment on the roof of a building. Because of the finite dimension of the base surface or ground sheet, standing waves arise thereon, and these result in a horizontal component in the field intensity. In the construction of ultra-short-wave beacons known in the art comprising two keymodulated reflector dipoles in an arrangement presenting mirror-image relationship to the guide beam or radio beacon course, the two horizontal components of the two side diagrams present a phase shift in reference to each other according to whether the right-hand or the left-hand refiector is closed, that is, elliptically polarized Waves occur in each of the two side diagrams by virtue of reflection relative to the vertical plane of symmetry which contains also the guide beam. The example consisting of the simplest receiving antenna, that is, the vertical dipole, may be cited 'to prove that, in the presence of an inclination of the dipole, the radio beacon course or guide 1 beam apparently shifts, and it is evident that consequently an airplane flying along curves and fitted with an antenna being perfectly vertically polarized in horizontal flying positionwould experience a corresponding shift of the guide beam as a function of its flying position. As a matter of factytheaircraft, for the reception of radiations from a beacon station, has an antenna subject to more complicated polarization as aresult of its metallic masses, etc., and this also results in a shift of the guide beam in a way as indicated.

The present invention will be more clearly understood by reference to the following detailed description, which is accompanied by a drawing, in which Figure 1 is a vector diagram explanatory of my invention, Figure 2 is a plan View of an embodiment of my invention, while Figures 3, 4 and 5 are elevational views of modifications of my invention.

The assumption is made that the beacon antenna radiates waves subject to linear polarization. Fig. 1 illustrates the situation in a plane of symmetry containing the guide beam. In this plane, the vertical components V1 and VB: of the two side diagrams are in agreement, and this is true also, in so far as size or quantity is concerned. of the horizontal, components H1 and Hit, though the horizontal components because of reflection are displaced in phase an angle'of degrees. At this point, therefore, the guide beam will be found with an antenna subject to purely vertical polarization. If, now, the receiving dipole is turned about a horizontal axis, the result is that for one of the 'side'diagrams it will fall more in the direction of the resultant R1 or Rn of the two field intensity components, and for the other side diagram farther away from this direction.

In other words, with such a receiver antenna the guide beam would no longer be located iri'the plane of symmetry, but laterally thereto in another plane in which the resultants, so far as their absolute values are concerned, will no longer be alike. I

Now, according to the invention the undesired horizontal component is compensated in the radio beacon course and optionally also in other directions at least dimininshed by the aid'of a supplementary radiation presenting predominantly horizontal polarization. This supplementary radiation may be produced by exicting, together with the others, one ormore auxiliary radiators mounted at suitable points, the excitation being at the frequency and rate of the keying of the.

beacon, itbeing immaterial so far as the basic idea of the invention is concerned whether such excitation is obtained by means of radiation 0011- pling or ina direct manner or by direct supply or feed. 'However,-the auxiliary radiators should preferably be disposed symmetrically in reference to the radio beacon course plane. p I An'illustrative embodiment of the-invention'is shown in Fig. 2. On a base area F, assumed to be rectangular, is mounted in the center the energy-fed vertical rod' A, while laterally in reference thereto are mounted the two keymodulated reflector rodsRi and R2. The, guide beam will then be in a position at right angles to the line connecting the three rods. Practical experience has shown that the relationship between the vertical component and the horizon!- 'tal component in the radio beacon course or ment according to the invention would be, for' instance, if in lieu of this inconvenience the shape of the horizontal base area were formed in such a way, say, by the provision of extensions, etc., that the horizontal component in the direction of the beacon course is diminished. In the exemplified embodiment Fig. 2 two horizontal bars H1 and H2 of suitable length have been added.

In the illustrative embodiment-Fig. 3, there is connected with each of the reflector dipoles R1 and R2 a small horizontal radiator as indicated at H1 and H2, respectively, with phase shifting means P1 and P2, respectively, being provided at the junction point. The said phase shifters and the length of the auxiliary horizontal bars should be so chosen that in the beacon course the field intensity diagram of the horizontal component attains a minimum value. By varying the size and the phase of the additional or auxiliary component it will always be possible, at least'in one direction, for example, in the beacon course or guide beam, to absolutely secure perfect compensation of the horizontal component. The contact members T1 and T2, Fig. 3, represent the reversing switch means for the reflector dipoles.

. In Fig. 4 isshown an exemplified embodiment in which the compensation of the horizontal component is obtained by radiation-coupled auxiliary. radiators H1 and H2, while the embodiment of Fig. 5 comprises energy-fed radiators which are-associated with thesame feeder lead S. as the chief radiator, and'which, if desired, may be keyed. alternately. Also in this organization phase shifting means may be included as shown in Figure 3.

* I claim:

1. In abeacon antenna system comprising a vertical radiating system for radiating a vertically. polarized beam, of radiant energy, said. radiating system being mounted on aground sheet of finite area whereby a horizontally polarized component of said beam is produced, the

.method of compensating for the distortion in said beam resulting therefrom which comprises radiating an, auxiliary horizontally polarized wave of such amplitude and. phase that said horizontally polarized component is neutralized.

2. A beacon antenna systemcomprising .a vertical radiating system for radiating a vertically vpolarized beam, said radiating. system being mounted on a ground sheet of finite area whereby a horizontally polarized component of said beam isproduced and means for radiating a horizontally polarized wave of such amplitude and phase that the said horizontally polarized component is neutralized.

' 3. A beacon antenna system comprising a vertical radiating system for radiating a vertically polarized beam, said radiating system being mounted on a ground sheet of finite area whereby a horizontally polarized component of said beam is produced and means for radiating a horizontally polarized wave of such amplitude and phase that the said horizontally polarized component is neutralized in the direction of said beam.

4. A beacon antenna system comprising a vertical radiating system for radiating a vertically polarized beam, said radiating system being mounted on a ground sheet of finite area whereby a horizontally polarized component of said beam is produced and means for radiating a'horizontally polarized wave of such amplitude and phase thatthe said horizontally polarized component is neutralized, said means comprising a plurality of horizontal conductors disposed in a vertical plane passing through said radiating system and at right angles to said beam.

5. A beacon antenna system comprising a vertical radiating system for radiating. a vertically polarized beam, said radiating system being mounted on a ground sheet of finite area whereby a horizontally polarized component of said beam isproduced and means for radiating a horizontally polarized wave of such amplitude and phase that the said horizontally polarized component is neutralized, said means comprising a plurality of horizontal. conductors disposed in a vertical plane passing through said radiating system and at right angles to said beam and means for energizing said conductors.

6. A beacon antenna system comprising a vertical radiating system for radiating a vertically polarized beam, said radiating system being mounted on a groundsheet of finite area whereby a horizontally polarized component of said beam is produced and means for radiating a horizontally polarized Wave of such amplitude and phase that the said horizontally polarized component is neutralized, said means comprising a plurality of horizontal parasitic radiators disposed in a plane passing through said radiating system and at right angles to said beam.

'7. A beacon antenna system comprisinga vertical radiating system for radiating a vertically polarized beam, said radiating system being mounted on a ground sheet of finite area whereby a horizontally polarized componentof said beam is produced and a plurality of horizontal conductorsdisposed in a plane passing through said radiating systemat right angles to said beam and means for energizing said conductors with a wave of such amplitude and phase that the horizontally polarized component of said beam is neutralized.

KURT FRANZ

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