Attenuation of slotted waveguide aerial parasitic side lobes - is achieved by plate filter installed in plane of emission

摘要

An attenuator is used to get rid of parasitic side lobes caused by interference in the output of slotted waveguides. The slots are alternated about the lengthways axis of symmetry of the guide. Attenuation is achieved by the use of a resistive filter (24) supported by end struts (25) from the slotted face of the waveguide. The plane of the filter is parallel to that of the short guide wall (21) and is positioned at least lambda o/4 away from the slotted face along the axis of symmetry (x-x'), where lambda o is the aerial operating wavelength. The filter plate having a depth of lambda o/2 may be laminated, the resistive component being a ferrite or some material having similar dielectric and resistive properties.