DE3144319A1 - "HORN RADIATOR" - Google Patents

Description

German Federal Post 2451

The invention relates to a horn antenna in which the funnel-shaped widening inner wall of the horn is provided with grooves.

Grooved horns of this type are often used in the microwave range because of their favorable properties. If dimensioned appropriately, they have good adaptation of the feed waveguide in a broad frequency band and directional characteristics with high axial symmetry and low cross-polarization. To achieve these properties, the groove dimensions, especially their depth, must be measured precisely. For example, it is known (IEEE Transactions Vol. AP-26, No. 2, March 1978, pp. 367 to 372) that the groove depth between the aperture (groove depth Z one quarter of the wavelength) and the neck of the horn (groove depth £ one half a wavelength) should be changed continuously. Three different ways of making the grooves in the funnel wall are known from the literature.

These three known embodiments according to different references are for a better overview in a single one and consequently fictitious Fig. 1 summarized. The arrangement of the grooves perpendicular to the funnel wall (according to FIG. 1) is suitable for all funnel opening angles <* (DE-OS 28 36 869). The attachment perpendicular to the emitter axis (according to 2 in Fig. 1) is for small opening angles <A preferable (DE-OS 26 50 388, DE-OS 29 30 932, DE-OS 25 09 619, DE-AS 26 23 755, DE-AS 25 25 358) “The attachment in parallel to the radiator axis (according to 3 in Fig. 1), however, is for large Oil opening angle is preferable (NTG technical reports antennas, Volume 57, page 84, Fig. 5).

In very slender horns (FLL »0) the groove configuration of one 1 corresponds to that in Figure 2, in wide open horns (<9 & - · φΡή). To that of the third deep groove horns that have so compact dimensions that they made

German Federal Post 2451

a single block of metal can be made by turning, must when using groove arrangement 1 or 5 first the (cone, bell or bottle neck shaped) Funnel contour can be generated and only then can the grooves be pierced.

When using groove configuration 2, the previous generation of the funnel contour is sometimes omitted. in that the narrow webs between the grooves are not funnel-shaped, but rather as circular cylinder pieces with corresponding the funnel contour can be formed with a modified radius. However, the disadvantage of this groove arrangement is that the Excavation of the grooves in the immediate vicinity of the horn neck is made more difficult by the fact that the groove depth at this point of the horn is only slightly smaller than the radius of the Feeder waveguide.

The invention is based on the object of showing a grooved horn, during the manufacture of which the aforementioned Difficulties are easily circumvented.

This task is performed with a horn radiator in which the funnel-shaped widening inner wall of the horn is parallel to the radiator axis incised grooves is provided, according to the invention dadurch.gelöst that the end faces the partition walls remaining between the grooves each run perpendicular to the radiator axis and that the funnel contour is determined by the axial distance between these end faces (Fig. 2),

In addition to being easier to manufacture, the grooved horn radiators designed according to the invention also have the following advantages on:

(1) Leave to be due to the configuration of the radiator all geometric dimensions and the surface properties of grooves and

German Federal Post 2451

It is particularly easy to check partition walls.

(2) The design of the inner wall of the horn does not complicate the manufacturing process possible, not only conical, but also well-known specially curved funnel contours with bottle neck (e.g. DB-AS 26 23 755) or a bell shape. You have to make use of this option when using a grooved horn radiator with a large opening angle and short overall length, low cross-polarization is to be achieved.

(3) To improve the adaptation of the horn antenna you can individually as well as combined all known measures for dimensioning such as shaping the transition zone on the funnel neck and the grooves adjacent to the funnel neck, e.g.

- an adaptation zone between the feed waveguide and

the first groove in the form of a smooth-walled waveguide intermediate piece with a diameter larger than that of the feeder waveguide but smaller than that smallest diameter of the funnel-shaped widening groove structure (DE-OS 29 20 757),

- deeper (also narrower and closer together) grooves than in the rest of the horn (IEEE Transactions, Vol.AP-26, No. 2, March 1978, pp. 367 to 372),

- undercut grooves (IEEE Transactions, Vol.AP-24, Wo. 6, November 1976, pp. ₈ 786 to 792; DE-OS 28 36 869),

- Bottle neck-shaped contouring of the ends of the groove partitions (DE-AS 26 23 755; DE-OS 26 50 388).

German Federal Post 2451

3U4319

(4) Uur due to the simple geometry of the invention Grooved horns built up are their precise numerical calculation and optimization of the radiation properties of the horn taking into account 5

- the reflection and wave type conversion at the funnel neck and in the aperture,

- as well as a dielectric cover plate as weather protection

possible. A tolerance analysis can also be carried out in this same way.

(5) Due to the structure of the horn antenna, in addition to the Manufacturing by turning, other known technologies can also be used, e.g.

- Electroplating ( without losing the core!), 20

- Diecast,

- Cold deformation ('cold hobbing ¹ , Proc. 1975 IEEE-MTT-S Intern. Microwave Symp., Pp. 232 to 234),

which are suitable for the production of particularly precise emitters (with millimeter waves) or for larger quantities (in directional radio and for small ground stations with primary focus excitation).
30th

The invention is described in more detail with reference to FIGS. Show it

1 shows the representation of the embodiments according to the prior art, which has already been dealt with

German Federal Post 2451

2 shows the schematic structure of the one designed according to the invention Grooved horn radiator (in longitudinal section),

Fig. 3, as a first embodiment of the invention, a grooved horn radiator with a specially shaped funnel

contour,

Pig. 4 the directional diagrams (main polarization (CP) in the E and Η plane, cross polarization (XP) in the 45 ° plane) of the radiator according to Fig. 3 for 10 GHz,

Pig. 5 the frequency response of the reflection attenuation for the radiator according to FIG. 3,

3-dB,
Fig. 6 shows the frequency response of the V5-dB, 10-dB, 15-dB and

20 dB widths of the directional patterns of the main polarization in the E and Η plane for the radiator according to Fig. 3,

7 shows the frequency response of the maximum cross polarization (ΧΣ'ηιοτ) ^{in the} 45 ° plane for the radiator according to FIG. 3,

Pig. 8 as a second embodiment of the invention Grooved horn radiator with a larger waveguide diameter compared to FIG. 3

FIG. 9 shows the directional diagrams (main polarization (CP) in FIG

E and Η planes, cross polarization (XP) in the 45 ° plane) of the radiator according to FIG. 8 for 10 GHz.

In Fig. 2, a longitudinal section through a grooved horn radiator according to the invention is shown schematically. the The inner wall of the horn is formed by a larger number η of coaxially arranged grooves, the partitions of which are in end faces ends that are perpendicular to the longitudinal axis of the radiator.

German Federal Post 2451

In the basic representation of the Pig. 2 you are a constant depth and width of the grooves and a constant Thickness of the partitions assumed. The axial distance between the end faces is also constant. As a result the funnel contour is conical. In those shown later Embodiments, however, these dimensions are not necessarily constant.

In order to clearly define the dimensions given in table form for the other embodiments (FIGS. 3 and 8), Pig. 2 each of the η grooves, starting from the feed waveguide with the inner radius a _i , assigned an ordinal number 1 to η; aj is therefore the inner radius of the first groove, aJ 'its outer radius. The same applies to the radii of the outermost groove a _n and a _n ^f . a _& is the outermost radius of the grooved horn. The depth of the grooves is denoted by t 1 to t, the end faces are each axially spaced 1 ″ to 1 from one another.

ει η

The axial distance between these end faces determines the funnel contour, the course of which is not subject to any fundamental restriction. Technically interesting embodiments are characterized by compliance with the condition 1 ^ i O ₉ ks 1,2, ... η. An analysis method for simulating the electrical properties (radiation behavior, adaptation of the feed waveguide) has been developed for such grooved horns. 2 below indicated dielectric cover plate - based on known design practices - can be dimensioned in an iteration process. This gate approach is clearly superior to conventional empirical design in terms of time. The usefulness of the grooved horns designed according to the invention is to be demonstrated on the basis of two exemplary embodiments in which radiators were dimensioned for use in the X-band.

German Federal Post 2451

3U4319

10

Pig. 3 shows the true-to-scale longitudinal section of a grooved horn with a small aperture (diameter 79 mm = 2.63λ "at 10 GHz) and short overall length (ξ «^ = 21 mm £ 0.7 * at 10 GHz),

which was dimensioned for low cross polarization. For this purpose, it is necessary with such compact horns to profile the funnel contour. This is achieved using the dimensions shown in the following table (dimensions in mm). The first column of the table is Pig. 2 explained ordinal number of the groove, followed by the inner and outer groove radii, the depths of the grooves and the axial spacing of the end faces from one another. It is assumed that the number of grooves is η = 8, the feed waveguide radius a _A of 11.5 mm and the outer radius of the groove

horns of a.

41 mm.

k * k 15.0 \ ^X k 1 12.0 18.5 11 2 2 15.5 22.0 8th 2 3 19.0 25.5 7.5 3 4th 22.5 29.0 7.5 4th VJl 26.0 32.5 7.5 4th 6th 29.5 36.0 7.5 3 7th 33.0 39.5 7.5 2 8th 36.5 7.5 1

German Federal Post 2451

In Pig. 4 shows the radiation properties of this horn for the design frequency of 10 GHz; she are characterized by a good rotational symmetry of the directional characteristic for the main polarization as well as by high Polarization purity off. The frequency responses of the reflection «- Attenuation, the beam widths and the maximum false polarization are shown in FIGS. 5 to 7. The input reflection of the radiator (Fig. 5) was determined by using optimized deeper grooves on the horn neck; she is in the wgsejitliehen determined by the ratio a ./λ. For applications where better customization is needed, let's see Provide a larger waveguide diameter (see second embodiment in Fig. 8).

The directional diagrams show. that the Strähler broadband can be used is. The shape of the main lobe (Fig. 6) is up to the 15 dB point (typical value for the edge drop during illumination of a primary focus-fed parabolic mirror) in the H and Ε planes almost the same and hardly dependent on frequency.

Between 9 and 11 GHz, the maximum cross-polarization in the 45 ° plane (Fig. 7) is significantly better than -4-0 dB. Values of Cross polarization around - 45 dB and below are at the limit of the resolution of the measuring station used, then the posts through

- the anechoic measuring chamber,

- the waveguide components downstream of the pathogen,

- the wrong polarization of the transmitting antenna,

- Alignment errors of the transmitting antenna and the object to be measured

in the order of magnitude of the incorrect polarization of the investigated Spotlight. The phase center of the radiator is in the opening of the feed waveguide, it is in all directions (up to about the 15 dB point of the main lobe) and practically constant within the specified frequency band (- 10 ° maximum variation).

8 shows the construction to scale of a second exemplary embodiment the invention. This spotlight was also

German Federal Post 2451

if designed for low cross polarization. He has the same aperture size and a similar contour as the radiator according to FIG. 3, but a larger feed waveguide diameter. TJm in turn broadband low cross polarization To achieve this, primarily the groove depth had to be modified.

The following table shows the dimensioning (dimensions in mm) for a number of grooves of η = 7, a feeder waveguide radius of a, β 15 m and an outer radius one Grooved horn of a_ * 41.0 mm.

CL

k * k ^a k * k \ 1 15.5 18.5 8.8 5 CVJ 19.0 22.0 8.0 3 3 22.5 25.5 8.0 4th 4th 26.0 29.0 8.0 4th 5 29.5 32.5 7.5 3 6th 33.0 36.0 7.5 2 7th 36.5 39.5 7.5 1

German Federal Post 24-51

Because of the very good agreement between the measured and the properties of the grooved horns according to the invention, obtained by means of computer simulation, according to Pig, 3 (see. Fig. 4 "to 7) is for the radiator according to Pig. 8 on the Manufacture of a model has been omitted. The one in Pig. The data given in FIG. 9 are results of computer simulations. The main polarization of this radiator is obtained at the design frequency of 10 GHz according to Pig. 9 almost the same directional characteristic as with the spotlight according to F £ g. 3> but slightly higher mispolarization · As one of the following As can be seen in the table, the maximum cross-polarization for this radiator is less frequency-dependent. This Behavior also applies to the width of the club in the same way. Due to the larger diameter of the feed waveguide the reflection attenuation could be significantly improved.

Frequency (GHz) ^ max < ^dB > 9.0 10.0 11.0 Reflection
damping 23.6 30.0 35.7 3 dB 37.7 /
37.0 35.4 /
35.2 35.1 /
35.5 Club 5 dB
broad
j_ fr / -p ________ 4-9.5 /
48.5 46.7 /
46.6 46.9 /
47.6 Level 10 dB
(Degree) 73.7 /
72.3 70.9 /
71.3 72.3 /
73.3 15 dB 96.0 /
94.9 93.6 /
94.7 94.5 /
94.5 20 dB 118.2 /
117.9 115.5 /
116.2 115.4 /
113.0 - 42.8 - 48.1 - 44.9

31U319

Deutsche Bundespost 24.5I

The embodiments discussed assume a rotationally symmetrical one Structure of the horn antenna. However, embodiments are also possible without departing from the solution principle of the invention with elliptical or rectangular cross-section conceivable, live the in Pig. The dielectric cover shown in the aperture shown in Fig. 2 is also a dielectric filling the funnel Use applicable.

Claims (10)

Deutsche Bundespost 2451 horn radiator (10) claims 1. Horn radiator, in which the funnel-shaped widening inner wall of the horn is provided with grooves cut parallel to the radiator axis,
characterized in that the end faces of the remaining between the grooves Partition walls each run perpendicular to the emitter axis <■ * »> and that the funnel contour by the axial distance of these End faces is determined from each other (Fig.2). 2. Horn antenna according to claim 1, characterized in that that the depth and the width of the grooves and the strength of the partitions between the grooves and the axial distances of the end faces are kept constant from one another along the contour and, consequently, those by the end faces The contour of the horn defined by the partition walls is conical (Pig.2). 3. Horn antenna according to claim 1, characterized in that the depth and / or width of the grooves and / or the ^ 20 Thickness of the partitions between the grooves along the Contour according to the desired electrical properties of the radiator (directional diagram for main polarization, Size of the maximum Pehlpolarization, input reflection) are formed stepped. 4. Horn antenna according to claim 3, characterized in that that determined by the end faces of the partitions The contour of the horn is bell-shaped (Fig.3,8). 5. horn antenna according to claim 3, characterized in that the fixed by the end faces of the partitions Deutsche Bundespost 2451 3 I 4 4 O | placed contour of the horn is designed like a bottle neck. 6. horn radiator according to claim 1, characterized in that the horn has a circular cross-section (Pig. 2,3,8). 7. horn antenna according to claim 1, characterized in that that the horn has an elliptical cross-section. 8. horn antenna according to claim 1, characterized in that that the horn has a rectangular cross-section. 9. horn antenna according to claim 1, 2 or the following, characterized in that a dielectric in its aperture Cover is provided (Fig.2). 10. Horn antenna according to claim 1, characterized in that that a dielectric insert filling the funnel is provided.