Abstract. The miniaturization of devices and the increase of operating frequencies are two important issues for communication system development. This requires a high degree of integration, higher performance and lower cost. Isolator is an important non-reciprocal passive component for source protection. In most cases, the non-reciprocal effect is based on field displacement phenomenon induced by a magnetized ferrite material. In this paper we propose a new design of a coplanar isolator based on field displacement, composed of a non symmetrical coplanar transmission line, made from a ferrite layer and ground plane below.Simulations were performed using HFSS software. Measurements were made on a first 1000 µm-thick YIG film sample giving 1 dB of insertion losses and 17 dB isolation and on a second sample made from a 150 µm-thick YIG ferrite sample giving an insertion loss lower than 2 dB. Interesting applications of this isolator structure are considered.