Planar Pyramidal Horn Antenna Without Any E-Plane Flaring for 5G Applications

This paper presents, for the first time, a planar implementation of a pyramidal horn antenna for 5G millimeter-wave (mmWave) applications. A substrate integrated waveguide (SIW) based planar H-plane horn antenna is designed and judiciously modified to eliminate flaring in the E-plane. This enables the antenna to achieve nearly symmetrical radiation patterns in both E- and H-planes, emulating the characteristics of a conventional 3D pyramidal horn in a compact, planar form. A flag-shaped copper strip, printed on the top surface of the lower substrate and fed by a coaxial probe, ensures uniform excitation. Additionally, two pairs of corrugated metallic strips are integrated (along the periphery of the horn) at the top and bottom surfaces of the lower and upper substrates, respectively to enhance aperture field uniformity. A trapezoidal dielectric loading is introduced at the aperture to improve gain. The fabricated prototype operates across two bands: 25.16–30.96 GHz (20.67%) covering key 5G bands (n257, n258, n261), and 31.54–33.44 GHz (5.85%). Peak measured gains of 12.66 dBi at 28.5 GHz and 13.78 dBi at 32.5 GHz are achieved. Good agreement between simulated and measured results confirms the effectiveness of the design for compact, high-gain 5G antenna systems.