the two embodiments shown in the figures represent a microwave component which forms a microwave circulator which may be designed to fulfil the function of a microwave isolator through a reflection - free closure of one of its three gates of its microwave guiding arrangement by means of a suitably dimensioned load impedance . this microwave component comprises a housing consisting of a substantially tub - shaped housing part 1 and a lid part 2 . the substantially tub - shaped housing part 1 comprises a bottom portion 3 of at least substantially square circumference and four wall portions 4 , 5 , 6 , 7 which follow the circumference of the bottom portion 3 . a first wall portions 4 forms the wall of the housing part 1 which is visible in fig3 ( view y ). a second wall portions 5 forms the part of the housing portion 1 which is visible in fig2 ( view x ), a third wall portion 6 forms the portion of the housing part 1 which is visible in fig4 ( view z ), and the fourth wall portion 7 forms the portion of the housing part 1 which is visible in a side elevation from the right , opposed to the view z . the housing part 1 with the bottom portion 3 and wall portions 4 to 7 is preferably made as an integral whole from a substantially planar , magnetically permeable material by a process without metal removal , for example is stamped and folded from a magnetically permeable metal plate . the lid part 2 is also manufactured in a similar manner . the wall portions 4 to 7 are shaped substantially rectangularly . at their edges facing away from the circumference of the bottom portion , they have stud - type projections 8 which will enter corresponding , mating cavities 9 in the lid part 2 when the housing part 1 and the lid part 2 are joined together . the housing part 1 and the lid part 2 may be joined to one another by gluing , welding , soldering , or flanging or bending of the stud - type projections 8 . any other connection method of the housing part 1 to the lid part 2 which leads to a similar result is also possible . the wall portions 4 to 7 do not continue to the corners of the substantially square circumference of the bottom portion , but have voids in the regions of these corners . in these comers , bores 10 are provided in the bottom portion 3 which serve as screw holes for fastening the microwave component in an appliance or the like in which the microwave component is utilized . these bores have circular circumferences ; alternatively , they may also be formed as slots . the housing 1 , 2 in the construction described above forms part of a magnetic circuit in which furthermore a number of substantially disc - shaped flat components is included which are arranged in a stack between the bottom portion 3 and the lid part 2 . in order of stacking , these are , starting with the component adjoining the lid part 2 : a first ferrite disc 11 , a planar inner conductor 12 , a second ferrite disc 13 , an intermediate element 14 , a circular permanent magnet 15 , a thermoflux disc 16 , and a strip 18 mounted with sliding possibility , separated by an air gap 17 in the arrangement shown . in this stack , the ferrite discs 11 , 13 ( ferromagnetic material ) together with the inner conductor 12 form the microwave guiding arrangement , for which the lid part 2 and the intermediate element 14 form the symmetrically spaced outer conductors in this example . the intermediate element 14 is made electrically conducting for this purpose . the intermediate element 14 is furthermore formed from a magnetically permeable material and thus at the same time forms a pole disc for distributing and homogenizing the magnetic field which is generated by the permanent magnet 15 and which permeates the microwave guiding arrangement 11 , 12 , 13 perpendicularly to the planar dimension of the inner conductor 12 . the intermediate element 14 is inserted with matching shape between the wall portions 4 to 7 . to avoid a magnetic short - circuit with these wall portions 4 to 7 , however , the intermediate element 14 is provided with recessed portions along its sides adjoining the wall portions 4 to 7 , so that the intermediate element 14 bears on the wall portions with narrow bridges 19 only . furthermore , the intermediate element 14 is preferably also manufactured from a magnetically permeable metal plate by a method without metal removal . instead of the intermediate element 14 described , a multiple intermediate element may be used , comprising an electrically conducting , foil - type part as the outer conductor for the microwave guiding arrangement 11 , 12 , 13 and an arrangement of magnetically permeable pole discs in a modification of the embodiment shown . the strip 18 in the embodiment shown comprises a flat , magnetically permeable metal plate and lies flat against the bottom portion 3 . the strip 18 together with the air gap 17 forms a magnetic tuning element which is geometrically changeable and which is present in the magnetic circuit . shifting of the strip 18 in a direction parallel to the line a -- a over the bottom portion 3 changes the contour , in particular the width , of the air gap 17 , and thus changes the magnetic permeance thereof . this changes the magnetic field strength in the entire magnetic circuit , and thus also in the region of the microwave guiding arrangement . a simple and accurate tuning of the microwave component is rendered possible in this manner . in the region of the bottom portion 3 where the strip is arranged with sliding possibility , an elongate opening 20 is provided in the bottom portion 3 , for example a stamped - out portion , which can be partly covered by the strip 18 and which extends substantially in the sliding direction of the strip 18 . the tuning properties of the magnetic tuning element can be influenced by the choice of contour of this opening 20 . openings 21 and 22 , through which a displacement of the strip 18 , and thus a tuning operation can still be easily carried out also , for example , when the microwave component is mounted in an appliance , are provided in the first and the second wall portion 4 , 5 , respectively , along the edges where these respective wall portions 4 , 5 lie against the circumference of the bottom portion 3 . a separate mechanical fastening of the strip 18 to the bottom portion 3 is not shown and may indeed be absent , because the two elements are retained in their mutual positions by magnetic attraction . in addition , however , this position of the strip 18 may also be ensured by means of a glue , a locking paint , or the like . the inner conductor 12 has three connection conductors 23 , 24 , 25 for forming the three gates of the microwave component . these are passed to the exterior from the housing 1 , 2 of the microwave component through suitably arranged recesses 26 , 27 , 28 in the first , third , and fourth wall portions 4 , 6 , 7 , respectively , such that an electrical insulation of the inner conductor 12 with respect to the housing 1 , 2 is safeguarded . the fixation of the assembly position of the substantially disc - shaped components 11 to 18 , wherein the air gap 17 results from the previously chosen assembly positions of the elements 11 to 16 and 18 , is provided by two support elements 29 , 30 which extend along the third and fourth wall portions 6 and 7 , respectively , with matching shapes ( and indeed with positive retention ) between the bottom portion 3 and the intermediate element 14 . these support elements 29 , 30 are electrically conducting , but magnetically non - permeable , and are preferably made from aluminum . they define the spatial position of the intermediate element 14 with respect to the bottom portion 3 , i . e . they define the interspacinig of these two elements . in addition , they represent the essential electrical connection between the housing part 1 and the intermediate element 14 . the support elements 29 , 30 here fill up part of the spatial region inside the microwave component which is bounded by the bottom portion 3 , the intermediate element 14 , and the wall portions 4 to 7 . this spatial region further contains the permanent magnet 15 and the thermoflux disc 16 , as well as the magnetic tuning element with the strip 18 and the air gap 17 which can be influenced thereby . a partial space 31 adjoining a sub - portion of the bottom portion 3 is left open by the components listed above inside the spatial region described . this partial space 31 is indicated with a bold broken line in fig4 and 5 . in this partial space 31 , which is immediately adjacent the bottom portion 3 and thus has a good electrical and especially thermal contact with the bottom portion 3 , it is preferable to position the load impedance mentioned above by means of which one of the connection conductors of the inner conductor 12 , preferably the first connection conductor 23 , can be connected free from reflection . the partial space 31 present here renders possible a load impedance arrangement which can be designed for high power losses in relation to the dimensions of the housing 1 , 2 of the microwave component . a microwave isolator of a high power class and having very compact dimensions can thus be constructed . a load impedance with a power dissipation in the range of between 50 and 200 w is envisaged in particular . this large load impedance can be accommodated inside the housing 1 , 2 without an increase in the dimensions of the bottom portion 3 . the arrangement of the load impedance adjacent the bottom portion 3 further safeguards a thermal uncoupling from the microwave guiding arrangement 11 to 13 . the strip 18 is first inserted into the housing part 1 during assembly . then the support elements 29 , 30 are inserted into the housing part 1 . the thermoflux disc 16 and the permanent magnet 15 are then positioned in the spatial region lying between the support elements 29 , 30 and the bottom portion 3 or the strip 18 , and this spatial region is covered with the intermediate element 14 . to ensure the air gap 17 being present , the height of the support elements 29 , 30 in the viewing direction of view w must be greater than the sum of the heights of the strip 18 , the thermoflux disc 16 , and the permanent magnet 15 . instead of the single thermoflux disc 16 shown for reasons of simplicity , an arrangement of several thermoflux discs may be used in practice . it is advantageous to fasten the permanent magnet 15 and the thermoflux disc 16 on the intermediate element 14 in a pre - assembly step , for example by gluing , and to place the subassembly 14 , 15 , 16 thus prepared with the permanent magnet 15 forward onto the support elements 29 , 30 , i . e . in the direction of the bottom portion 3 . the microwave guiding arrangement with the ferrite discs 11 , 13 and the inner conductor 12 is placed layer by layer on the intermediate element 14 , and is fastened in that the lid part 2 is provided and fixed to the housing part 1 . the assembly of the entire microwave component can be carried out stackwise in a mounting jig which , for example , comprises three pins which are threaded through corresponding holes in the bottom portion 3 , which are not shown in the embodiments , for assembly purposes and which define the positions of the individual , disc - shaped components 11 to 16 and 18 . after the lid part 2 has been fastened , the microwave element is taken off the pins . the permanent magnet 15 is incorporated in the fully magnetized state . the magnetic field necessary for the operation of the microwave component is tuned by means of the movable strip . the opening 20 in the bottom portion 3 may be used for mechanical access to this strip 18 as long as this opening is accessible , in dependence on the assembly position of the microwave component . the embodiments shown in the figures differ from one another as regards , the shape of the partial space 31 as a result of the shape chosen for the permanent magnet 15 each time . whereas in the first embodiment of fig1 to 7 the disc - shaped permanent magnet has a radial dimension which corresponds substantially to that of the ferrite discs 11 , 13 , the second embodiment of fig1 , and 8 to 12 shows a permanent magnet of smaller radial dimensions . to achieve a comparable volume for the permanent magnet 15 , the thickness of the disc - shaped permanent magnet 15 in the second embodiment ( fig1 ) is chosen to be greater than in the first embodiment . similarly , the partial space 31 in the first embodiment extends for a major portion in the intermediate space between the permanent magnet 15 and the strip 18 , i . e . in the air gap 17 . by contrast , the partial space 31 in the second embodiment lies to a much greater extent in a spatial region between the bottom portion 3 and the intermediate element 14 , bounded laterally by the first wall portion 4 at one side and by the permanent magnet 15 and the strip 18 at the other side ( fig1 ). the smaller radial dimension of the permanent magnet 15 in the second embodiment in addition renders possible an increase in the partial space 31 for the accommodation of a load impedance , as compared with the first embodiment .