Substrate integrated hard horn antenna

The horn antennas are probably the simplest and widely used microwave antennas. They are basically a device which provides a transition between waves propagating in a transmission line and wave disseminating in an unbounded medium such as free space. The bulky geometry of traditional horns has always been a limitation for these antennas to be used in compact form at high frequencies. In recent years, the invention of substrate integrated waveguide (SIW) technology has revolutionized the employment of planar horn antennas integrated into microwave and millimeter-wave circuits.