A Ka-Band Splash Hat-Fed Reflector Antenna With Ultrawideband and ETSI Class IV Radiation Patterns for 5G Backhaul

Wide bandwidth and high sidelobe suppression are critical for the application of 5G backhaul networks. However, the reported hat-fed reflector antennas show limitations in these performance aspects. In this communication, several techniques are incorporated into a Ka-band splash hat-fed reflector antenna to achieve ultra-wideband and ETSI Class IV radiation patterns for 5G backhaul application. To suppress edge diffraction and obtain wide impedance matching, a novel splash hat feed, consisting of an upward-tilted corrugated brim, a zigzag-shaped sub-reflector, a multi-step dielectric head and a multi-step dielectric rod, is proposed. The proposed multi-step dielectric rod functions not only as an impedance matching device, but also as a TE11-HE11mode converter to improve radiation performance. To further suppress far-out sidelobes, a metal cylinder with a foam absorber covering its inner surface is proposed for the reflector. Moreover, a self-developed Visual Basic (VB) code is designed to convert sub-efficiencies and additional specific criteria into optimization objectives, which helps to suppress the far-out sidelobes while ensuring high antenna efficiency within a wideband. A prototype was fabricated and measured. The measured relative impedance bandwidth (|S11|E-andH-planes compliant with the strictest ETSI envelopes, Class IV.