EP0475294A2 - Dielectric antenna - Google Patents

Abstract

The invention relates to a dielectric antenna which is supplied from a waveguide operated in monomode. The dimensioning of the antenna results from the relationship L/Lep = ((D/Lep-0.6) DEG (DLep-0.6)+(1.3..2.7)) DEG 6/Qep Qep being the square of the relative dielectric constant, increased by one, Lep being the wavelength in the space which is filled homogeneously with dielectric, D being the maximum lateral dimension (D) of the antenna and L being the maximum length (L) of the antenna. Fig. 1 shows a side view of the antenna according to the invention. <IMAGE>

Description

The invention relates to a dielectric antenna according to the preamble of claim 1.

Multiple exciters for parabolic mirrors are used to generate shaped directional characteristics or to provide different main beam directions with a fixed antenna. The excitation distance determines the main lobe distance reached and thus the overlap level of neighboring main lobes. The minimum excitation distance is given by the necessary aperture size of the individual radiators, which is required to generate a suitable illumination characteristic. However, this usually leads to an insufficient overlap level.

Dielectric antennas with correspondingly suitable radiation properties are known from DE 22 60 648. However, the constructive form of the antennas shown there is too complex.

The same applies to DE 38 29 370. The solution described there requires a very complex mechanical construction. Furthermore, the radiation properties deteriorate due to the pathogen penetration. Therefore, the principle of the invention in DE 38 29 370 cannot be used for more than two radiators.

The object on which the invention is based, to arrange an antenna with suitable bundling properties so closely adjacent as an exciter in a mirror antenna that a sufficiently high overlap level is achieved is achieved by the invention characterized in the main claim.

Advantageous developments of the invention are characterized in the subclaims.

The advantages that can be achieved with the invention consist in particular in an extremely simple antenna structure.

An embodiment of the invention is shown in the drawing and will be described in more detail below.

Fig. 1

eine Seitenansicht der Antenne

Fig. 2

ein Richtdiagramm eines Strahlers aus Polystyrol (H-Ebene)

Fig. 3

ein Richtdiagramm eines Strahlers aus Polystyrol (E-Ebene)

Fig. 4

ein Richtdiagramm eines am Ende verjüngten Strahlers (H-Ebene)

Fig. 5

ein Richtdiagramm eines am Ende verjüngten Strahlers (E-Ebene)

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Fig. 1

a side view of the antenna

Fig. 2

a directional diagram of a radiator made of polystyrene (H level)

Fig. 3

a directional diagram of a radiator made of polystyrene (E level)

Fig. 4

a directional diagram of an emitter tapered at the end (H plane)

Fig. 5

a directional diagram of a tapered radiator at the end (E plane)

wobei Qep das Quadrat der um 1 vergrößerten relativen Dielektrizitätskonstanten ist.Fig. 1 shows the side view of an antenna according to the invention. It consists of a cylindrical dielectric body with the following relationship between the greatest length L and the greatest diameter D, in each case based on Lep, the wavelength of the homogeneously dielectric filled space,

$\text{L / Lep = ((D / Lep-0.6) · (DLep-0.6) + (1,3..2,7)) · 6 / Qep,}$

where Qep is the square of the relative dielectric constant increased by 1.

Part of this body is a transition area 1 with a length of (0.6 ... 0.8) · Lep. Here the body is fed by a dielectric filled waveguide 2 with a diameter of (0.7 ... 1) · Lep. At the dining point there is a cross-sectional jump 3 of the body to (1.1 ... 1.4) · Lep. The transition to the largest transverse dimension D of the emitter takes place here, depending on the diameter difference, either abruptly, stepwise or conically. Despite the simple shape and the small transverse dimensions, excellent radiation properties can be achieved with the dimensioning described. As an example, the directional diagrams measured in the X-band are one Emitter of polystyrene reproduced (Fig. 2 and 3). This is an emitter according to the above design rule with a length of one free space wavelength. The directional diagrams show an almost rotationally symmetrical course and an excellently designed phase center. FIGS. 4 and 5 show the directional diagrams of this radiator for the case where the diameter at the radiator end 4 (FIG. 1) has been reduced by 0.3 × Lep over a length of 0.1 × Lep. This measure results in an even lower side lobe level and leads to a further improvement in the diagram symmetry.

Claims (7)

Dielectric antenna, which is fed by a preferably single-wave hollow line,
characterized,
that the greatest length (L) of the antenna in the case of rotationally symmetrical antennas results from its greatest transverse dimension (D) or, correspondingly in the case of antennas with a square cross section, from its greatest side length according to the relationship

$\text{L / Lep = ((D / Lep-0.6) · (D / Lep-0.6) + (1.3 ... 2.7)) · 6 / Qep}$

where Qep is the square of the relative dielectric constant increased by one and Lep is the wavelength in the homogeneously dielectric filled space,
that from the feed waveguide (2) there is a cross-sectional jump (3) to a diameter or side length of (1.1 ... 1.4) · Lep and that from the cross-sectional jump (3) Transition area (1) of length (0.6 ... 0.8) · Lep extends to the largest transverse dimension (D). Dielectric antenna according to Claim 1, characterized in that the transition in the transition region (1) of the antenna to the largest transverse dimension (D) of the antenna takes place in a jump at the end of the transition region (1). Dielectric antenna according to Claim 1, characterized in that the transition which takes place in the transition region (1) of the antenna to the largest transverse dimension (D) of the antenna is graded in at least two steps. Dielectric antenna according to Claim 1, characterized in that the transition to the largest transverse dimension (D) of the antenna takes place in the transition region (1) of the antenna. Dielectric antenna according to one of Claims 1 to 4, characterized in that in the case of radiators with the largest transverse dimensions (D) above 1.5 · Lep, the transverse dimension in the end region of the radiator over a length (4) of (0.1 ... 0, 2) · Lep is reduced by (0.2 ... 0.4) · Lep. Dielectric antenna according to Claims 1 to 5, characterized in that the feed waveguide (2) carries hybrid modes. Dielectric antenna according to one of Claims 1 to 5, characterized in that the feed waveguide (2) is designed as a web waveguide.

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