DE2348988C3 - Waveguide filter and harmonic filter arrangement - Google Patents

Description

measurement are chosen so that the fundamental wave and
whose harmonics of any TE _m "mode io
pass through the waveguide without substantial attenuation, while all other modes by the The invention relates em waveguide filter, best-slits are coupled out, which is provided with an approach from a piece of a rectangular waveguide, order, which the decoupled in the narrow wall Absorbs undesired modes essentially parallel to the minor axis of the waveguide cross-section, denoting that the absorption has continuous wall slits, the spacing and desired modes of which are selected by a dimension on the outside so that the fundamental wave and the waveguide (1 ) densely applied micro- whose harmonics of any TE _n , "mode the wave absorption material (S) is achieved. Pass through waveguides without significant attenuation,

2. Waveguide filter according to claim 1, characterized 20 while all other modes are characterized by the slots, that the width of each slot * (4) are coupled with an array less as twice the strength of the see which the uncoupled undesired

] Waveguide (1) forming material. Fashions absorbed.

3. Waveguide filter according to one of the preceding- As such filters are the waves to be suppressed the claims, characterized in that the as absorb instead of reflecting, they are suitable Distance between two adjacent slots (4) especially for insertion between a power two Slot widths. power transmitter and a consumer. Most

4. Waveguide filters after one of the previous high-power transmitters are extraordinary the claims, characterized, üaß sensitive to reflected power, as sol everyone Slot (4) extends over the full width of the 3 ° before power to considerable damage to the end narrow Wall (3) of the waveguide extends. tubes can lead. Waveguide filter of the input

5. Waveguide filters of one of the types described above have been known for many years the claims, characterized in that (compare e.g. "Proc. of the IRE", October 1959, both narrow walls (3) with slits (4) and to p. 1762 to 1769, and »1959 IRE Wescon Conven belonging Microweilen Absorp.'ionsmaterial (5) 35 tion Record ", Vol. 3, Part I, pp. 112 to 118). are provided. The first step was to deal with those undesirable

6. To eliminate waveguide filter according to one of the preceding modes, which can be passed through transverse slots according to the claims, characterized in that the microwave absorption material (5) in the wide wall of the rectangular waveguide can be extracted from a pein. However, such slots not only couple a single layer of ferrite-loaded silicone rubber 4 ° modes of the harmonic frequency, but also the chuks that are made to the associated narrow r £ ₁₀ fundamental wave. In order to prevent this, wall (3) had to be laid and connected to it in such a way that the modes coupled out on the wide wall were completely inserted into a secondary waveguide through the slots (4) in the wall (3). E _1n covered. Mode of the fundamental frequency can not lead

7. Waveguide harmonic filter arrangement with 45 adapted loading of the secondary waveguide, a plurality of waveguide filters according to one was achieved that the undesired modes absorder the preceding claims, were thereby marked. This absorption method underscores the fact that the filters (6, 7, 8) are connected to one another with the help of a separate secondary hollow tube that at each intermediate surface, when one went on, additional modes desired between two successive filters (6, 7; 5 °) were adopted Via transverse slots in FIGS. 7, 8) a fraction of the energy of waves that decouple in the narrow wall of the waveguide and eliminate any TE _m "mode at any one.

gene harmonic frequency progress in a These known absorption filters have besides

other mode or several other modes caused by the secondary waveguide

transformed wildly, the disadvantage of the following figure 55 high space and material requirements

ter be dampened. they are expensive and difficult to manufacture. It must

8. Waveguide-harmonic filter arrangement after ensuring that the load of the sekun-claim 7, characterized in that the hollow conductor is precisely adapted. In addition, longitudinal axes must be the filters (6,7,8) curse each other at the coupling slots exactly prescribed th and the filters are connected to one another, 60 dimensions and distances are maintained that each filter compared to the previous one with them at the frequencies to be suppressed Filter in the same predetermined direction around its resonance lead to an effective coupling in the Is rotated longitudinal axis. secondary waveguide. This will

9. Waveguide harmonic filter arrangement after the manufacture of such filters is expensive.

Claim 8, characterized in that the object of the present invention is 65

Degree of twist of a filter (6, 7, 8) in the creation of the undesired modes off

to the next is between 20 and 40 °. sorting waveguide filter with less

10. Waveguide harmonic filter arrangement after wall than before. In the case of a waveguide filter

Eighth fashions by an at £ S of the π5 that ie, To ™ " » ^? "" * ' ^Ve * ^unden

Waveguide densely applied microwave absom F ₁ Sr hf ^] ?? ™ ^{¥ ύ} * ^τ && ™ * π the previous one

üonsmaterial is achieved. uen Absorp Filter in the same predetermined direction around seme

According to the invention, all v «nr _E Z'S ^§ τ'ΐ t" _Λ ""

Mode (with in any whole tooth abwri λ / ^ ^Ta ^ henbuch der Hochfrequenztechn.k «

Corresponding vibration types gSdHnfpS7 _nde Jί edigTich un3 29 «ί Il a ™? l \ ° V ^ ΐ ^ 'J" T

• A _Pr srhmalen wall H ^ Hr.hiit.-L n> "'S. ⁿ una ZViS) it is known per se, several rectangular

will ihen ^m by εΐ H ^Q f ^r _R ^SChhtZe waveguide sections iers applied Mil ™ ΐι S "* ¹ *" ^{DiCSe measures} ™ twisted behind the other to arrange, is used in the known case only

äfübdfk are n £ Tr, ^? " ^{as the means for} polarization rotation of the TE ₁₀ wave

ÄLSi: £££ S

a simple absorbent covering on the m PrölVr _a k η

iSSiSSfJS ₁ SAr ^ «- HS

In the filter designed according to the invention has

requires less material, and the dimensions are excepted for the purposes of harmonic filtering

that the Svhlitzbreite below a certain maximum conductor required in order to positively measure mitausgekoppelte harbors, so that no extraction of the ground takes place 35 TE ₁₀ -WeIIe of the absorption unlock Wähwelle. In a preferred embodiment, a single filter according to the invention acts as a "moderate invention, st d, e frying of each slot less the filter" for attenuating all "narrow wall modes" than twice the strength of the waveguide, regardless of the frequency and thus also the material . The distance is preferably a large part of the harmonic energy destroyed between two adjacent ones. Slitting two slotted 40 can be the aforementioned arrangement of several such

^bre ' ^te "· .... · jo, ^{Fliler as a full} harmonic filter to attenuate everyone

It can be beneficial if each slot is served by harmonics of the fundamental frequency

the full width of the narrow wall of the waveguide. Preferably, the amount of twist is from

extends. Advantageously, both narrow filters can be between 20 and 40 ° to the next

walls with protection and associated microwave 45 the best adaptation to the fundamental frequency between

Be provided adsorption material. In an advantageous way to achieve individual filters, the length

Adhesive embodiment of the invention, the ab- each filter is preferably equal to a quarter or

sorption ratio from a single layer of an odd multiple of a quarter of the

distant-weighted silicone rubber, which is to be the length of the fundamental frequency

associated narrow wall of the waveguide and so 50 The invention is described below in terms of execution

connected with it is that it explains the slots in the examples with reference to drawings

Wall completely covered. F i g. 1 is a schematic view of an invented

In some cases it is desirable to also use the waveguide filters designed in this way.

FIG. 2, which is transmitted by the filter according to the invention, shows schematically the arrangement of several

re " ₀ -modes of higher order (ie the modes 55 waveguide filter to a harmonic filter arrangement ·

with m greater than 1) and only Fig. 3 shows in a diagram the introduction

r £ ₁₀ mode. This task is attenuated, depending on the frequency for an on

Send further development of the invention consists of an opening according to FIG. 2.

Arrangement with several hollow according to Fig. 1, the drawn filter has a piece of ladder filters, which is characterized in that the 60 waveguides 1 of rectangular cross-section with a pulp filter are connected to each other that on each th wall 2 and a narrow wall 3 on. The interface between each two successive dimensions of wall 2 and wall 3 are gefolgenden filtering selects a fraction of the energy of WEI, that the waveguide 1 the ΓΕ ,, -. Len mode at which in any TE _m "mode at a required basic working frequency,
any harmonic frequency progresses into a 6 _5. In each narrow wall 3 a number of slots 4 are cut with mutual modification or several other modes, and each is converted by the following filter Waveguides are attenuated. This arrangement is preferably of a width corresponding to the wall material thus forming

runs parallel to the minor axis of the hollow TE _n , "-mode not attenuated, but the conductor cross-section, ie perpendicular to the wide filter 6 T £ _m " -modes with η φ 0 independent of the wall 2. The exact number of Slots is not in frequency. Particularly important at the interface between the fiI -s, and the slits need not be arranged with tern 6 and 7 looking in some "TE _n " mode equidistant from one another, 5 advancing waves whose electric field direction, although it is generally more favorable, if the distances parallel to the minor axis of the waveguide are equal to each other. Preferably (and therefore runs to the slots in the wall), the distance between the slots is equal to that through the intermediate surface with the same electrical slot width. Purpose and application of the field direction to continue Because of the relative rotation slots are described further below: Each hole of the filter 7 is now a component slot group is covered with a layer 5 of ferritic electrical field now in a direction parallel to the silicon rubber, which is micro to the large Axis of the waveguide of the filter 7. wave-absorbing material acts rten: An energy component is converted into one or the other T £ _mn mode with η φ 0 during operation through the waveguide 1, propagating waves are known to generate a current 15 when the waves cross the interface between the waves in the walls of the waveguide 1 running through filters 6 and 7. Waves traveling in any TE _n "mode - where m is an interface between filters 6 and 7 in any integer - carry a current flow T £ _mn modes (with η φ 0) are converted in one direction parallel to the longitudinal direction of the naturally von cm filter 7 in the above-described slot 4, while in another mode 20 attenuated, while the waves running in the TE ,,, "mode generate current flow, the transversely remaining energy continues unattenuated. A similar width direction of the slot runs. The licher process takes place at the interface between two slots, the width of which is roughly equal to the material thickness, see filters 7 and 8, where additional energy is in, have practically no influence on waves in 7 "E _mn modes (with η φ 0 ) and thus some TE _m "mode, because these waves, the 25 of which is attenuated. Such mode transformations are induced current flow parallel to the longitudinal direction which, however, only runs at harmonic frequencies of the fundamental frequency slots 4, through the slots not coupled frequency instead. The waveguide section of each filter is and therefore continue to run in the longitudinal direction of the waveguide 1 without being attenuated by the layer 5 for forwarding the fundamental frequency in the 7 "E _{1" mode.} Since the wall currents do not determine or allow any other modes to propagate, however, the wall currents transversely to the planting with the fundamental frequency. With other slots flowing, a certain energy breakdown is used: higher modes at the fundamental frequency are partially coupled through the slots and "cut off" in the ferrite end. Therefore, the _{microwave absorption layer 5 made of Si, which is difficult in the TE 10} mode, passes through the filter 6 with the fundamental frequency bewelikonkautsch.uk absorbed. The hollow energy described, unaffected by the relative non-rotating filter, thus acts as a selective mode filter, which continues into the filters 7 and 8. In fact, the TE _{follows n} , "-mode without significant attenuation and allows the electric field to pass through the rotation of the waveguide. Energy and other fashions attenuate. of harmonic frequencies in any TE _n , “-Preferably sol! The width of the slots in two modes will, however, be _{equal to the thickness of the waveguide material in TE m} "modes (with η φ G) , but will be converted and then attenuated. The overall requirement that this condition is not necessarily complied with. The 4 ° order thus acts as a harmonic filter arrangement. and wider slots are also useful - but lets the fundamental frequency pass without attenuation, bar, only no TE _n , "modes are allowed to be coupled through. It can easily be seen that the attenuation of the pelts is. Accordingly, the greater the number of slots, the greater the spacing and harmonic frequencies are selected so that the required number of attenuation of the modes to be attenuated as shown in FIG. 2 is achieved, 45 is filter.

while TE _m "modes remain undamped. Although a 30 ° rotation is preferred at each intermediate The filter described so far can TE ₁₀ -mode surface, but the exact angular amount at the fundamental frequency for which it is designed, and not essential. The greater the angle of rotation, so as to pass through the TE _n “modes in the case of harmonics. Some more energy is converted into TE _mn modes, such filters can now be a Filteranord- 50 but if the rotation is too large, look for energy planning combine that without damping only in the fundamental mode TE _1n in the mode TE _ai überzurE ₁₀ Mode at the base frequency and all go, which does not attenuate other frequencies due to the construction of the waveguide. Such a hollow is let through. In contrast, if the rotation is too small, the conductor-harmonic filter arrangement is shown in FIG. 2 only shows a small amount of energy in the higher one. The harmonic filter shown in Fig.2 is converted into 55 modes. The best results have the order consists of three waveguide filters a 6, 7 and 8 at angles of rotation between 20 and 40 ° result in connection with FIG. 1 described for the length of the filters 6, 7 and 8 is a fourth version, and these filters are set against each other in such a way that their longitudinal axes are aligned with the wavelength of the fundamental frequency. In addition, a multiple of this quarter wavelength in front of the filter 7 has been rotated around its longitudinal axis so far that 60 has been struck. In this arrangement, its wide wall forms an angle of 30 ° with a good match between successive fiI of the wide wall of the filter 6. Likewise tern guaranteed, and each at intermediate surfaces re the filter 8 is rotated by 30 ° relative to the filter 7. Inflected energy is destructive. All reflections The length of each filter 6, 7 or 8 is equal to one of harmonic frequencies are attenuated below a quarter-wave length or an odd multiple of the filter and do not bring a quarter-wave length of the fundamental frequency, for the difficulty.

the harmonic filter is designed. F i g. 3 is a diagram showing the insertion

In operation, the filter 6 has continuous attenuation as a function of the frequency at the filter

arrangement according to Fig.2 shows. You can see that the The fundamental frequency is not attenuated, while the second harmonic is attenuated by more than 5 dB becomes and the higher harmonics by only a little less. These numbers meet the requirements of a harmonic attenuator, while the

overall dimensions of the Filtcranordnung are only very larger than the dimensions of the hollow itself. The filter arrangement is therefore well suited for subsequent installation in the system where no filtering is initially provided \ especially where the available space is often very small

1 sheet of drawings

50 '

Claims (1)

One of claims 7 to 9, characterized in that the patent claims: characterized in that the length of each filter (6, 7, 8) is equal to a quarter or an odd number. 1. Waveguide filter, consisting of a piece multiples of a quarter of the wavelength of the a rectangular waveguide, which is in the narrow fundamental frequency. len wall essentially parallel to the small one
Axis of the waveguide cross-section extending Has wall slots, the distance and distance of which