In the paper, the authors describe a novel H-plane horn antenna for an experimental wireless link operating in frequency bands 71 to 76GHz and 81 to 86GHz. The horn antenna was designed considering a Substrate Integrated Waveguide (SIW) technology, the waveguide WR12 was used as a feeder. In order to improve transition between a thin-substrate SIW horn antenna and the air, they combined two approaches; a printed transition and a dielectric load. That way, a better impedance matching and better radiation properties were reached.