DE1193125B - Reelable waveguide - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

HOIb

German class: 21c -S / 03

Number: 1193 125

File number: T 24725 VIII d / 21 c

Filing date: September 18, 1963

Open date: May 20, 1965

The invention relates to a reelable waveguide for broadband transmission of linearly polarized waveguides electromagnetic waves emanating from a longitudinally welded, helically corrugated metal tube with an elliptical cross-section, the lowest frequency to be transmitted being the specified Band is about 20% greater than the cutoff frequency of the useful wave in the waveguide and the first occurring Interference frequency is above the highest band frequency, with a ratio of the mutually perpendicular standing, effective axes of the waveguide cross-section, which is smaller than 0.81.

For the transmission of electromagnetic waves of very high frequency, it is known to use waveguides with different To use cross-sectional shapes. The cross-sections of these waveguides generally have round or rectangular cross-section. They are already smooth waveguides with an oval cross-section known.

It is often used for special purposes (e.g. antenna feed lines for moving stations) required that you have a reelable waveguide that allows the proper transmission of linearly polarized electromagnetic waves. For this purpose it is more recent Time a reelable waveguide with an oval cross-section became known. It consists of a longitudinally welded, corrugated metal ear. A linearly polarized electromagnetic wave is used as the useful wave Transmit wave whose ^ -vector is perpendicular to the major axis of the oval cross-section. It has it has been shown that the first versions of this waveguide were not yet optimal with regard to Attenuation and freedom from reflection. The unwanted drum-type waveguide

Applicant:

Telefunken

Patent collecting society m. B. H.,

Ulm / Danube, Elisabethenstr. 3;

Hackethal wire and cable works

Corporation,

Langenhagen near Hanover

Named as inventor:

Dipl.-Ing. Wolfgang Krank, Backnang (Württemberg);

Dipl.-Ing. Günter Möhring,

Langenhagen near Hanover

Reflections are essentially caused by the profile shape of the waveguide. Also is the cushioning of the waveguide depends on its cross-sectional shape.

The aim of the invention is therefore, with a given frequency band for the above-mentioned waveguide to show an optimal dimensioning with regard to broadband transmission.

This object is achieved with the new waveguide in such a way that, according to the invention, the distance (S) between two successive corrugation peaks is between 0.1 and 0.25 of the wavelength and that the ratio of the effective axes of the waveguide cross-section satisfies the following condition:

0.8

with t _x tv t ₂ <0.2 O ₁ .

Here is

α _χ the major clear axis,

O ₁ the small clear axis,

a _{2 is} the maximum major axis caused by the corrugation,

b _s the maximum minor axis caused by the corrugation, a correction factor for determining the effective major (minor) axes, 4K ₁

which depends on the profile shape of the corrugation is and is between ± 0.65,

the wave depth in the direction of the major axis,

the wave depth in the direction of the minor axis.

With reference to the figures, the invention is intended in the following are explained in more detail.

509 570/354

bz - b.

I 193 125

3 4

In FIG. 1 is a helically corrugated reference to damping. To achieve optimal Waveguide shown in longitudinal section. Attenuation would have to be the ratio of the effective

_{Hollow axes} A _{CT 0} , _{4 should also be} selected for special applications, as this is due to the highly selected

Conceivable ladders with oval cross-sections without «»>

that the corrugation of the reelable waveguide 5-drawn vertical line A in FIG. 7 received

ben-shaped. In FIG. 2 is drawn in schematic. An optimal waveguide in terms of

Way, a longitudinal section through such a waveguide is attenuation and flexibility, as has been shown

shown. given when the ratio ™ is about 0.6 in the figure. 3 is a cross section of a drum a _w
bare corrugated waveguide with oval cross-section io, like the one indicated by the vertical line i? shown in the. Here U ₁ denotes the large clear F i g. 7 is shown.

Axis and a _% by the corrugation of the waveguide. If the required relative bandwidth Af is greater than

conditional maximum major axis of the oval transverse 10%, it can be seen from FIG. 7 in an analogous manner

cut With J ₁ is the small clear axis and with 6, _similar ratios of ^ - read off,

the maximum minor axis caused by the corrugation 15 a _w

designated. The corrugation of the waveguide can be designed in different ways. Preferably, the built waveguide can be made with regard to the flexibility, the corrugation, however, in such a way that it periodically attenuates and / or optimally advances the bandwidth. It then runs in such a way that the distance S is taken. 20 between two successive well mountains of the

In practical use, an oval corrugated pipe is required

waveguide below a ratio of 0.4 of the χ χ

H ■ - is O - "

effective axes - hardly used. Using the 10 ~~ ~ 4

Fig. 7 should "ι below the possible dimensioning a _{5 d as} * _{fe wofcei} ^ _χ ^ sation are explained. On the vertical axis *> ο ο ₅ ο
the F i g. 7 is the relative frequency bandwidth of the mean free space wavelength of the bear to be transmitted, while the frequency band is indicated on the horizontal axis. Advantageously, the ratio, formed from the effective minor axis b _{w, in} this case, the corrugation is made helically, and the effective major axis a _{w is} shown. If one considers the cross section of the waveguide according to where the lower limit of the bandwidth of the invention is, then for each slope S (cf. a distance of 20% (corresponding to the dashed Fi g. 4, 5 or 6) in the vertical On the level the Wireing line E) is assumed, while the function of a capacitive diaphragm and in the horizontal upper limit the first interference frequency level that of an inductive diaphragm. The frequency responses are assumed. This is shown in FIG. 7 through the 35 of these two elements are not exactly opposite, so curved solid line G is indicated. It means that a small residual reflection is added to each element according to the formula. But the slope will be in the order of magnitude

1 selected from - ^ -, the resulting value has the

- 0 11 [^ - V 1 + 14 (- ^w \ - 0 0234 ⁴ ° ^{au e man} of the following impurities f a minimum bezüg-

'\ cL \ o)' \ aw j ' borrowed the reflection factor of the waveguide. Will the

The slope S with respect to the wavelength λ is somewhat smaller

This curve can be used for eUipsen-like and oval j λ _{m id} j _{fa d reflection factor}

Waveguide can be modified somewhat, with only the one in 4 ^e '

Increase the constant value of 0.0234 45 given in the above formula somewhat, but it remains within tolerable limits, by a certain amount after plus or minus _dw λ _dj j; _H
is canceled. Appropriately, at the 10 ^{s 6}
practical sizing is not exactly based on the above steps. For dimensioning, this means approaching the limit (solid curved line G) _,, " Λ. ^ τ. ·· ι. ο -ι. ^ J ^ r * so ^that 50 ^{'when the high Gan} S ^{S zwlschen} Joe ^and T ^ ^1' arise acute boy with higher wave types, no reflection by the existing Restrefiexionen no sharp at Kritamungen of the waveguide over Verkopp-. It is preferable to choose a reflection peaks within the range to be transmitted of about 2 to 5% of the figure. 7 represents the frequency band occurring. For a perfect over-dashed curve F a distance of 2% from the transmission of a given frequency band must represent the first interference frequency that occurs Useful wave are applied, where lie. The above condition can of course also be converted to the hollow tube wavelength due to the dispersion behavior of the hollow tube. The specification for Leiters the attenuation at the lower end of the band but the limits of S are met when the gradient rises sharply. In the. F i g. 7, a value of 10% was applied for this angle of the corrugation (FIG. 1), which is favorable between 0 and 60 °. In the case of corrugated tube waveguides that have already been manufactured, including, represented by the dash-dotted par-oval cross-section, the angle of inclination in front of the parallel straight line D was . B. a bandwidth Af of preferably 10 °.

10 ° / ₀ to be transferred (see Fig. 7, vertically drawn out. For special purposes, the

Line C), a waveguide receives the largest corrugation and make it so that the slope

tn = «.; t,; i; + st f, - ~;“ \ τ ~ uu · “ ^δ ·» η ιι τ-ν angle <x continuously between two specified

flexibility for a ratio - from 0.73. This so " ₇ . , ^. * _n ,,, "" ..., JZ?,. ..

a "' values (e.g. -10 and +10) along the waveguide

dimensioned waveguide is not optimal in the longitudinal axis changes.

The formula described at the beginning, according to which the ratio, formed from the effective minor axis b _w and the effective major axis a _w , should be between the values 0.4 and 0.8, contains correction factors K ₁ and UT ₂ as well as the two quantities I. ₁ and t ₂ , which represent the wave depths. The correction factors JST ₁ and K ₂ in the waveguide according to the invention are between the values -0.65 and +0.65.

In general, the sizes ^ ₁ and t _{2 can be} different. For a rough calculation, however, one can assume that the wave depths I ₁ and t _{2 are} approximately the same. The following condition preferably applies to the wave depth:

h> h <0.2 O ₁ .

Based on the above prerequisites, three distinctive corrugated shapes can be distinguished will:

The in the F i g. 4 is designed so that the length Z _{1 of} a wave crest is equal to the a ° length Z _{2 of} a wave valley (S = Z ₁ + Z ₂ ), the correction factors K ₁ and K _{2 being} almost zero. In this figure, / denotes the wave depth defined above, while S represents the pitch. The sizes O ₁ , A ₁ , a ₂ and b ₂ represent the corresponding axes of the corrugated waveguide.

In FIG. 5 shows another special case of a possible corrugated shape. The length Z ₁ of a wave crest is greater than the length Z _{2 of} a wave valley, the correction factors K ₁ and K ₂ differing from zero and preferably having a value which is greater than zero. The size of the correction factor depends on the penetration of the field vector of the transmitted wave into the corrugation of the waveguide. This means that the correction factor K ₁ or K _{2 is} not only dependent on the dimensions Z ₁ , Z ₂ and t , but also on the shape of the curvature of the corrugation. In the case of the FIG. 5, the correction factors mentioned are positive.

In FIG. 6 is compared with that in FIG. 5, the reverse case is assumed. The length Z ₁ of a wave mountain is selected to be smaller than the length Z _{2 of} a wave valley. The correction factors K ₁ and K ₂ are also different from zero in this embodiment and are negative. If the curve of the corrugation deviates from that shown in FIG. 6 is selected, modifications are conceivable in which the correction factors are different from zero, but have a value which can be greater than zero.

Finally, a dimensioning example should be given in which the condition is set is that the relative bandwidth to be transmitted is 20%, with optimal flexibility requiring 5s

will. According to FIG. 7 there is a ratio for this -

U _w

of 0.676. It is assumed that the wave depth t _x of

the wave depth U is different and their ratio | -] -

Vi ₂ /

has the value 0.9, the correction factors K ₁ = 0.03 and K ₂ = 0.015 due to

of the selected profile the ratios - = 0.7 and

O ₁

^b f = 0.65.

Is z. If, for example, the major axis a _{x is} given, the dimensions of the waveguide can be calculated on the basis of the formula of claim 1. In the example carried out in practice, the pitch S

selected with -j- .

Claims (7)

Patent claims: 1. Reelable waveguide for broadband transmission of linearly polarized electromagnetic waves, which consists of a longitudinally welded, helically corrugated metal tube with an elliptical cross-section, whereby the smallest frequency to be transmitted of the given band is about 20% greater than the cutoff frequency of the useful wave in the waveguide and the first occurring interference frequency is above the highest band frequency, with a ratio of the mutually perpendicular effective axes of the waveguide cross-section which is less than 0.81, characterized in that the distance (S) between two successive corrugation peaks is between 0.1 and 0.25 of the wavelength and that the ratio of the effective axes of the waveguide cross-section satisfies the following condition: 4 K. CIw 1 + - ^ + 4K ₁ O ₁ ^ 0.8 with t _x «ai ₂ <0.2 O ₁ .
Here is a _x the major clear axis, O ₁ the minor clear axis, C ₂ the maximum major axis caused by the corrugation, b _{2 is} the maximum minor axis caused by the corrugation, K ₁ (K ₂ ) a correction factor for determining the effective major (minor) axes, which depends on the profile shape of the corrugation and is between ± 0.65, t _x = the wave depth in the direction of the major axis, t ₂ = - ^ r- ¹ - the wave depth in the direction of the minor ¹ axis. 2. Waveguide according to claim 1, characterized in that the pitch angle κ (of the corrugation) is between 0 and 60 ° and preferably has the value of about 10 ° (Fig. 1). 3. Waveguide according to claim 2, characterized in that the pitch angle continuously changes between two predetermined values along the waveguide. 4. Waveguide according to one of the preceding claims, characterized in that the correction factors (.RT ₁ or K ₂ ) meet the condition: - 0.65 < (K ₁ , K ₂ ) <+ 0.65 and that the wave depths (Z ₁ and ^ ₂ ) are approximately equal and satisfy the condition: i _l5 t ₂ <0.2 Ot ₁ (Figures 4, 5,6). 5. Waveguide according to claim 4, characterized in that the length (Z ₁ ) of a corrugated mountain is equal to the length (Z ₂ ) of a wave valley, the correction factors (Jf ₁ or Vf ₂ ) having the value zero (FIG. 4). 6. Waveguide according to claim 4, characterized in that the length (Z ₁ ) of a wave crest is greater than the length (Z ₂ ) of a wave valley, the correction factors (UT ₁ and Tf ₂ ) being ^{different from} zero and preferably one value that is greater than zero (Fig. 5). 7. Waveguide according to claim 4, characterized in that the length (Z ₁ ; of a corrugated mountain is smaller than the length (Z ₂ ) of a corrugated valley, the correction factors (Z ₁ or K ^ are different from zero and preferably have a value that is less than zero (Fig. 6). Considered publications:
Telefunkenzeitung, June 1962, no. 136, pp. 113 to 115. 1 sheet of drawings