Three new improvements have recently been made to the JET Ion Cyclotron Resonance Frequency (ICRF) antennae to increase coupled power density and to match through rapid coupling variations during Edge Localised Modes (ELM's); both of which are key developments for the future design of the ITER ICRF antenna. Firstly, 3dB couplers were fitted to two antennae in 2004/5. Secondly, an Externally-mounted Conjugate-T (ECT) system has been installed on two antennae during 2007. Thirdly, a major new ITER-Like Antenna (ILA) was installed during 2007 to couple an ITER-relevant power density using a close-packed array of straps, with ELM tolerance incorporated using an internal (in-vacuum) conjugate-T junction with each strap fed through in vessel matching capacitors from a common vacuum transmission line. The results achieved to date on all three systems and the implications for the ITER antenna design are discussed.