Multifunction RF systems which can operate with different RF functions like radar, communication and electronic warfare offer a variety of benefits beyond the well-known AESA (Active Electronically Steerable Antenna) features. To reach a sufficient technology maturity to start product development a series of challenges most stemming from the large required operation bandwidth have to be resolved. Dual-polarised low-loss apertures with array grids designed for a grating lobe and scan blindness free 60 conical Field of View (FoV) at the highest operational frequency have to be considered. The active components of the AESA and especially the T/R-M are required to be power efficient over the whole multifunction bandwidth and they shall be miniaturised to fit the array grid. RF functions like high speed datalink require linear high power amplification with low harmonics generation and interference suppression in receive is essential in order to maintain performance. Enablers for such broadband AESA are the GaN technology for T/R-M front-end components and SiCe BiCMOS technology for core chip and digital control of the T/R-M. The paper shows the state-of-the-art technology in Europe for multifunction RF Systems.