Dual-band circulators are a new literature topic and so far, they have always been realized in stripline technology, therefore with bulky boxes. Changing to microstrip allows to reduce the size of the device while keeping similar performances. Furthermore it enables better integration into antenna systems. This paper presents the first design of a ferrite dual-band circulator in planar technology, operating simultaneously on two chosen frequency bands. The isolation of the device is better than 20 dB at 5 and 10 GHz.