It is generally assumed that Ion Cyclotron Resonance Frequency (ICRF) antenna coupling is maximised when the shape of the plasma Last Closed Flux Surface (LCFS) matches the poloidal profile of the antenna. This is a relevant issue for plasmas at high triangularity, which are becoming more and more popular because of their favourable thermal confinement properties: in these configurations the LCFS is usually mismatched to the antenna curvature and the coupling could deteriorate, thereby limiting severely the ICRF power injection capability. While the dependence of the antenna coupling on the plasma-antenna distance in the equatorial plane of the tokamak is already well established for the JET A2 antennas, the effect of lower and upper triangularity could not yet be adequately assessed. Dedicated experiments have now been performed on JET with four different plasma configurations, characterized by large range of variation of lower lower and upper upper triangularity.