Abstract:
An R switch with a stator and a rotor with three paths wherein a central, straight interconnection is constructed as step transformers and formed bar-like by recesses incorporated laterally in the in the steps of the transformers in order to lower the low frequency limit of the HF signals which can be transmitted.

Description:
BACKGROUND OF THE INVENTION 
   The invention provides an R switch for switching connections between microwave waveguides on and off which has a structure which widens bandwidth by lowering the resonance frequencies of interconnections not in use thereby reducing coupling. 
   The European patent 0 276 582 discloses such an R switch with a stator, a rotor and three interconnections constructed as step transformers. In designing the R switches known from the art, it was totally disregarded that the non-active interconnections of these switches formed short-circuited cavities, which act as cavity resonators at certain frequencies. At these frequencies, the active paths, are affected so strongly that there is practically no longer any insulation between microwave waveguide, which is not connected, nor, with that, is there an error-free signal transmission. A resonance frequency of the non-active, curved paths is greater here than that of the nonactive straight interconnections, so that these two resonance frequencies limit a bandwidth of HF signals, which can be transmitted error-free by the R switches and, with that, limit the HF signals, which can be switched through. 
   SUMMARY OF THE INVENTION 
   In accordance with an embodiment of the present invention there is provided an R switch for switching connections between microwave waveguides on and off which has a parallelepiped stator having four side surfaces of which each have a central opening for connecting to a microwave waveguide. A rotor is disposed in an interior of a stator with its axis of rotation coaxial with a longitudinal axis of the stator and has a centrally disposed straight interconnection and two curved paths, i.e., interconnections, on either side thereof. Openings of the straight interconnection and curved paths are disposed in such a manner that, depending on a rotational position of a rotor, each opening can be connected using the straight interconnection or using one of the curved paths to each of the other three openings. The straight interconnection is constructed as a step transformer, and the step transformer of the straight interconnection is formed bar-like by recesses incorporated in the steps. 
   According to a feature of the present invention, the above-described R switch or the present invention, has an easily realized bar-like construction of a straight interconnection, constructed as a step transformer, that is constructed multi-stepped and that recesses are incorporated on either side of the last step of a step transformer. The invention objective of expanding bandwidth is easily carried out in production and can be realized inexpensively using a milling machine. In an embodiment of the invention the recesses are constructed on both sides of the last step. 
   The present invention includes an embodiment wherein the recesses are constructed on one side or the last step. Optionally, the invention provides a preferred embodiment wherein the recesses are constructed on both sides of the last step. 
   According to a further, advantageous development of the present invention, recesses are incorporated on either side of all steps in the step transformer of the straight interconnection, as a result of which a further lowering of a low-frequency limit of the R switch is possible. 
   According to a further advantageous development of the present invention, multi-step, bar-like constructions are formed as step transformers in curved paths and recesses are incorporated on either side of a last step of the step transformers of the curved recesses. 
   The present invention enlarges the bandwidth and is easily carried out in production and can be realized inexpensively using a milling machine. 
   According to a further, advantageous development of the present invention, recesses are incorporated on either side of all steps in the step transformer of the curved paths, as a result of which a further additional lowering of a low-frequency limit of the R switch is possible. 
   According to a further advantageous development of the present invention, a straight interconnection is constructed as a step transformer, in order to save material and weight, by omitting the step transformers in the curved paths, to the extent to which this is permitted by uncoupling. 
   Further advantages and advantageous developments of the present invention can be realized from the following description, the drawings and the claims. 
   Some examples of the invention are described in greater detail in the following and shown in the drawings 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a sectional representation along the line I—I in  FIG. 2  through an R switch of the present invention with a first bar-like configuration of a step transformer in a straight interconnection of a rotor, 
       FIG. 2  shows a front view of the straight interconnection of the rotor of  FIG. 1  in the direction II, 
       FIG. 3  shows a cross-section along the line III—III of  FIG. 4  through an R switch with a second bar-like configuration of the step transformer in the straight interconnection, 
       FIG. 4  shows a front view of the straight interconnection of the rotor of  FIG. 3  in the direction IV 
       FIG. 5  shows a sectional representation along the line V—V in  FIG. 6  through an R switch with a first bar-like configuration of a step transformer in straight interconnection and/or the curved path of a rotor, 
       FIG. 6  shows a front view of the straight interconnection or the curved path of the rotor of  FIG. 5  in the direction VI, 
       FIG. 7  shows a cross-section along the line VII—VII in  FIG. 8  through an R switch with a second bar-like configuration of the step transformer in the straight interconnection and/or curved paths, 
       FIG. 8  shows a front view of the straight interconnection or the curved paths of the rotor of  FIG. 7  in the direction VIII, and 
       FIG. 9  shows a sectional representation along the line I—I in  FIG. 2  through an R switch of the present invention with a first bar-like configuration of a step transformer in the straight interconnection of the rotor. 
   

   DESCRIPTION OF THE PROFFERED EMBODIMENTS 
     FIG. 1  shows the transverse sectional representation of an R switch  1 , which has of a stator  2  with end openings  3  to  6  for connecting waveguides, which are not shown in the Figure, and of a rotor  7 , which is disposed rotatably in stator  2 , with a central straight interconnection  8  and, on either side thereof, “curved” paths, i.e. interconnections,  9  and  10 , ends of which are parallel to axes  11  and  12 , which are at right angles to one another. The axes  11  and  12  also represent orientations of the waveguides adjoining the R switch  1 . Depending on a position of the rotor  7 , different waveguides, attached to the openings  3  to  6  of the stator  2 , are connected through. In the case of the position of the rotor  7 , shown in  FIG. 1 , the openings  4  and  5  and the openings  3  and  6  are connected with one another. Rotating the rotor  7  clockwise through 45° connects the openings  3  and  5  with one another. If the rotor  7  is rotated clockwise by a further 45°, the waveguides, connected to the openings  5  and  6  and the waveguides, connected to the openings  3  a  4 , are connected through. If the rotor  7  is rotated once again clockwise through 45°, an interconnection is created between the openings  4  and  6 . If the rotor  7  is rotated further clockwise by 45°, the arrangement of  FIG. 1  is obtained once again. 
   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   As far as dimensioning of the R switch  1  perpendicularly to a plane of the drawing is concerned, the stator  2  has essentially the shape of a parallelepiped and the rotor  7  has the shape of a cylinder. In order to reduce the external dimensions of the R switch  1  as far as possible for use in satellites and space vehicles, the interconnection  8  and the interconnects  9  and  10  are constructed as step transformers  13 ,  14 ,  15 , as a result of which especially space required by central parts of the interconnection  8  and the interconnects  9  and  10  is reduced. 
   As indicated in  FIG. 2 , the interconnection  8  as well as the interconnects  9  and  10  have a rectangular cross-section, so that the side walls of the step transformers  13 ,  14 ,  15  have a shape of stairsteps. A front view of the straight interconnection  8  in the direction A of  FIG. 2  consequently shows the front surfaces of the steps  16  to  19  of the step transformer  14 . 
   According to the example of the present invention, shown in  FIGS. 1 and 2 , the upper steps  17  and  18  of the step transformer  14  have the shape of narrow bars, which can be achieved because recesses  20  to  23 , which are drawn in  FIG. 1  by broken lines  24  and  25  as undercuts, are milled on either side of the steps  17  and  18  to form recess spaces between the  17  and  18  and walls of the interconnection. 
   In principle, a rotor switch has the disadvantage that the interconnection or path, which does not connect any stator openings with one another, acts as a cavity resonator, which is supplied with energy over the unavoidable gap between the rotor  7  and the stator  2 . Accordingly, for the rotor position of  FIG. 1 , the straight interconnection  8  acts as a cavity resonator. Since it is brought about by these means that signals nevertheless are transmitted between the interconnects, which are not connected through, such as between the interconnects  3  and  4  or the interconnects  5  and  6  of the present example, the bandwidth of the signals, which can be switched through error-free by an R switch, is limited by these resonance frequencies. The lower limiting frequency is formed here by a resonance frequency of the straight interconnection  8  and a resonance frequency of the curved interconnects  9  and  10  (here, for example, by rotating the rotor  7  clockwise through 45°, when the interconnects  9  and  10  are not active). 
   Extensive experiments have now shown that the resonance frequency of the straight interconnection  8 , acting as a lower limiting frequency of the R switch  1 , can very easily be decreased appreciably in order to enlarge the bandwidth of the signals, which can be transmitted error-free by the R switch  1 , by forming the step transformer  14 , as shown in  FIGS. 1 and 2 , at least partially bar-shaped by milling recesses  20  to  23  at the side of the steps  17  and  18 . 
   For example, in the case of a particular R switch with the name WR51 switch, which had a bandwidth of 19 to 22 GHz without the bar-like construction of the step transformer, is was possible to expand the bandwidth to 17.7 to 22 GHz in this way. This is of advantage particularly because the satellite band extends from 17.7 to 22 GHz, so that the WR51 switch, after being modified pursuant to the present invention, can be used without problems for switching signals lying within the satellite band. 
   A development of the present invention for expanding the bandwidth of an R switch is shown in  FIG. 3  in section along the line III—III drawn in  FIG. 4  and in  FIG. 4  as a plan view in the direction IV of the sectional representation shown in  FIG. 3 . In particular,  FIG. 4  shows that, contrary to  FIG. 2 , recesses  26  to  29  are milled not only at the sides of steps  17  and  18 , but also at the sides of steps  16  and  19  from the step transformer  32 . In the sectional representation of  FIG. 3 , this is indicated by means of broken lines  30  and  31 . The advantage of this is a further lowering of the resonance frequency of the straight interconnection  33 , which is inactive and acting as a cavity resonator, for example, as in  FIG. 3 , and, with that, a further lowering of the lower limiting frequency of the R switch  34 . In other respects, the construction and mode of action of the R switch, shown in  FIGS. 3 and 4 , is identical with the construction and mode of action of the R switch, shown in  FIGS. 1 and 2 , so that these do not have to be described again. 
   Further developments of the present invention for expanding the bandwidth of an R switch are shown in  FIGS. 5 to 8 . The advantage of this development is the fact that the low resonance frequency of the curved interconnects is lowered, when these are switched inactive by a rotation of the rotor and accordingly act as cavity resonators. The construction and mode of action of the R switch, in other respects, are identical with those of the R switch of  FIGS. 1 to 4 . 
     FIG. 5  corresponds to  FIG. 1  and, additionally, has recesses  51 ,  52 ,  53 ,  54 , as shown in  FIG. 6 , in the steps  48 ,  49  in the step transformers  13 ,  15  in the curved interconnects  9 ,  10 , which are represented in  FIG. 5  by means of broken lines  39 ,  40 ,  41  and  42  as undercuts. 
     FIG. 7  corresponds to  FIG. 3  and, additionally, has recesses  55 ,  56 ,  57 ,  58  as shown in  FIG. 8  in the steps  47 ,  48 ,  49 ,  50  in the step transformers  35 ,  36  in the curved interconnects  37 ,  38 , which are shown in  FIG. 7  by means of broken lines  43 ,  44 ,  45  and  46  as undercuts. 
     FIG. 9  corresponds to  FIG. 1 ; however, the curved interconnects  9 ,  10  do not contain any step transformers. 
   All distinguishing features, shown in the specification, the claims below and in the drawings, are inventive individually as well as in any combination with one another.