Abstract: A re-entrant resonant cavity 12 includes three parts 18, 19 and 20 which may be manufactured as metallized plastic components. The three parts 18, 19 and 20 are soldered to a multilayer PCB 23 using surface mount technology. The re-entrant stub 16 is in two portions with dielectric material provided by the PCB 23 between them. The cylindrical wall 13 surrounding the stub 16 is also divided into two sections 21 and 22 by the PCB 23. Vias 24 and 25 electrically connect the parts separated by the PCB 23. The pattern of the vias 24 and 25 determines the inductance of the cavity, and hence its resonance frequency. This enables cavities with the same geometry to be operated at different resonance frequencies by using different configurations of through connects. One of the sets of vias may be omitted in some cavities.

Abstract: A re-entrant resonant cavity 12 includes a first metallized molded plastic component 18, which comprises a re-entrant stub 17, an end wall 14 and a cylindrical side wall 13. The component 18 is surface mount soldered to a metallized PCB substrate 19. A rostrum 24 is located facing the end face 21 of the stub 17 to define a capacitive gap 22 with it. The end face 21 of the stub 17 and the rostrum 24 are configured such that relative rotation between them changes the profile of the gap 22 and hence the gap capacitance. By suitably locating the two parts during manufacture, a particular capacitance may be chosen to give a desired resonance frequency from a selection available depending on the relative angular position of the stub 17 and rostrum 24. In another cavity, the rostrum is replaced by an etched metallization layer of a printed circuit board.

Abstract: A re-entrant microwave resonant cavity comprises a stub 6. A cylindrical wall 2, first end wall 3 and the stub 6 are integrally formed. A second end wall 4 is defined by a metallization layer 8 deposited on a printed circuit board substrate 9. The parts are joined using surface mount soldering processes. The end 11 of the stub 6 defines a gap 12. A rostrum 14 faces the end of the stub 6. The rostrum 14 is manufactured separately and then fixed to the substrate 9. A dielectric sphere 16 is located between the end 11 of the probe 6 and the rostrum 14. The dielectric sphere 16 maintains the gap size during use and aids in correct positioning of the parts during manufacture.

Abstract: An antenna (10) having an emitter element which is positioned in front of a conductive reflector (13) and has a three-dimensional cast part. The cast part is implemented as conductive and has a closed peripheral structure (11) having alternating constrictions and bulges. The peripheral structure (11) spans an imaginary surface (14) which is intersected by at least two planes of symmetry (15.1, 15.3) of the cast part. At least two fastening elements (12.1, 12.2) are provided, which extend essentially perpendicular to the imaginary surface (14) and support the peripheral structure (11) at two points which lie on one of the planes of symmetry (15.1; 15.3). At the lower ends (16), the fastening elements (12.1, 12.2) are connected to the reflector (13), the fastening elements (12.1, 12.2) also being used for electrical excitation of the emitter element.

Abstract: An antenna (10) having an emitter element which is positioned in front of a conductive reflector (13) and has a three-dimensional cast part. The cast part is implemented as conductive and has a closed peripheral structure (11) having alternating constrictions and bulges. The peripheral structure (11) spans an imaginary surface (14) which is intersected by at least two planes of symmetry (15.1, 15.3) of the cast part. At least two fastening elements (12.1, 12.2) are provided, which extend essentially perpendicular to the imaginary surface (14) and support the peripheral structure (11) at two points which lie on one of the planes of symmetry (15.1; 15.3). At the lower ends (16), the fastening elements (12.1, 12.2) are connected to the reflector (13), the fastening elements (12.1, 12.2) also being used for electrical excitation of the emitter element.