PREDICTION OF SURFACE-WAVE RADIATION COUPLING ON MICROWAVE PLANAR CIRCUITS

A theoretical and experimental study is presented for spurious radiati on coupling induced by radiated surface waves on planar circuits, at f requencies up to 20 GHz. The radiation coupling phenomenon generated b y a planar line containing a discontinuity is modelled by an equivalen t E-field planar radiation pattern associated with the current wavefor m along this line in the presence of the discontinuity, It is observed that the direction of the main and side lobes of this pattern varies with frequency, The model is validated by measurements of radiation co upling obtained on microstrip configurations, up to 20 GHz. Theory and measurements agree very well, The model yields for instance the direc tions of maximum spurious radiation coupling on a planar line in the v icinity of a radiating line.