A comparison between breast tumour detection with a traditional lossy coupling medium based system and a system without coupling medium is performed, by numerical modelling and experimentally. While a system with lossy coupling medium offers surface wave reduction and protection from surrounding sources and obstacles it also demands good permittivity matching of the coupling medium to the breast tissue under investigation, as well as a high performance measurement system with a dynamic range exceeding 100 dB. The system without coupling medium offers possible direct detection of inhomogeneities with transmission losses of about 50...60 dB. The proposed contacting antenna system however needs further development in order to reduce stray fields and adoption to realistic breast tissue properties.