Patent Publication Number: US-6667671-B1

Title: Waveguide switch

Description:
BACKGROUND INFORMATION 
     German Patent No. 4 034 683 describes a waveguide switch having a stator with four waveguide terminal pairs and a rotor in which the waveguide paths are present, joining at least two waveguide terminal pairs. The signal paths are switched by the rotation of the rotor (thus also rotation of the waveguide paths in the rotor). 
     To achieve acceptable electric function (matching, isolation), a high precision is necessary in manufacture of the stator and rotor, and for the combination of these parts in particular, only a very narrow gap is allowed between the stator and rotor, so that a very complicated precision bearing is usually necessary. 
     SUMMARY OF THE INVENTION 
     The waveguide switch according to the present invention is composed of two partial shells, each having the halves of the waveguide structure, in particular symmetrically, preferably produced by the milling technique. The corresponding “switch path” is set by a simple, electrically conducting septum, for example, by rotation or displacement. 
     No complex rotor/stator geometry is necessary. Furthermore, other switch configurations are also possible. 
     A waveguide switch according to the present invention may be composed of parts that need not be produced with an extremely high precision, so that production costs are much lower than with switches according to the related art. In addition, short switching times can be achieved, because the masses to be moved in switching are very small. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1 a ,  1   b  and  1   c  show the basic design of an embodiment of the waveguide switch according to the present invention in three sectional diagrams. 
     FIGS. 2 a  and  2   b  show an open, three-dimensional diagram (like an exploded diagram) of the waveguide switch according to FIG. 1 for two different switch states. 
     FIGS. 3 a  and  3   b  show additional possible switch configurations. 
     FIGS. 4 a  and  4   b  show further possible switch configurations. 
    
    
     DETAILED DESCRIPTION 
     Parts that are essentially the same in different figures are labeled with the same reference numbers. The present invention is explained in greater detail below on the basis of two different embodiments. These embodiments represent only a fraction of the possibilities that can be achieved according to the principles of the present invention. 
     FIGS. 1 a ,  1   b  and  1   c  show three sectional diagrams through a symmetrical switch arrangement, section C—C usually representing the half-shell division of the complete arrangement, i.e., the stator half shell (not including the outer contour) with a movable element (shown here in the form of a rotor). The arrangement has four waveguide terminal pairs  1 ,  2 ,  3 ,  4 , where adjacent waveguide terminal pairs are arranged at right angles mutually. 
     Waveguide paths in the form of 90 degree E plane bends  12 ,  23 ,  34 ,  41  are inserted between adjacent waveguide terminal pairs in the stator in this arrangement, thus forming a branch at each waveguide terminal pair. Due to this arrangement, each stator half-shell has a solid area  5  at the center of the arrangement. In the complete branching area, i.e., within circle  6 , a gap  7  is provided between the stator half shells and an electrically conducting septum  8  is provided there. (Gap  7  only has an insignificant influence on the electric properties of the waveguide paths, because it is in the electrically neutral zone of the waveguide paths.) Septum  8  is shaped so that two opposing outer curvature contours  9 ,  10  almost emulate the contours of the two corresponding E plane bends. In other words, the E plane bends for desired waveguide paths  23 ,  41 are emulated by septum  8 . However, the partial areas of the other E plane bends are covered. In these covered areas  12 ,  34 , the waveguide paths are divided by septum  8  into two “partial waveguides” in the middle of their wide sides, so that the cut-off wavelength is much smaller in these areas than the wavelength of the useful frequency band and thus signal propagation is suppressed here. 
     A central rotatable placement of septum  8  in central solid area  5  permits very simple switching of the waveguide paths by rotating septum  8  by 90 degrees (see FIGS. 2 a  and  2   b ). 
     Septum  8  may be designed with sliding-action contacts, for example, but it is advantageous to arrange the septum in such a way that it is isolated from the waveguide area. 
     Furthermore, septum  8  may have a frequency-selective structure  13  (for example, elevations, ribs  16   c , recesses, grooves, holes, slots, material discontinuities) which compensate for disturbances due to the “partial waveguide openings” while also increasing the isolation between the “blocked” waveguide paths. 
     In addition, septum  8  may also be provided with markings  14 ,  15 , for example, in combination with a photoelectric barrier, for identification of the switch position. 
     Other switch configurations are also conceivable according to the principle described above. For example, FIGS. 3 a  and  3   b  show an arrangement where the switch function is implemented by displacement of a septum  16 . Septum  16  has two separate areas  16   a ,  16   b , one of which has the configuration of one of the switch positions. To permit displacement of these two areas jointly according to arrows  17 , a connecting part  18  which is inserted between areas  16   a ,  16   b  is located in a continuous waveguide path in one switch position (see FIG. 3 a ). 
     Either this connecting part  18  is designed to be electrically neutral (for example, lambda/4-transformation with transformation stages formed by projections  19  on connecting part  18 ) or the disturbance caused by the connecting part is compensated in the connecting part itself or in the corresponding waveguide path (through suitable discontinuities  20 ). 
     Specifically, the compensation of connecting part  18  may be designed as follows: 
     a) compensation by having the length of approximately a quarter wavelength, 
     b) connecting part  18  also has one transformer stage  19  for the adjacent waveguide sections, the dielectric being stepped or a dielectric having a different dielectric constant being used; the length of projections  19  on the connecting part which form the transformer stages corresponds to a quarter wavelength; 
     c) the septum has (additional) discontinuities which are displaced with the septum; for example, in FIG. 4 a : inductive discontinuity at the top, capacitive discontinuity at the bottom; 
     d) compensation by (additional) discontinuities/transformations (for example, a change in cross section of the waveguide in the area of connecting part  18 ) which are in the waveguide and are not displaced with it; this is possible if the discontinuities/transformations are in the parts of the waveguide that are operated together with connecting part  18  only in the conducting operating state. 
     In a manner similar to the above embodiments, the waveguide switch according to the present invention can be used in a plurality of different configurations, which also have more than four waveguide terminal pairs, for example, and with switching options having highly individual designs.