Stable phase‐centre horn antenna using 3D printed dielectric rod for aperture efficiency improvement of space‐fed antennas

Abstract

The design strategy to stabilise the phase centre (PC) of the conventional horn antenna using a shaped dielectric rod is presented for aperture efficiency improvement of space-fed antennas. In most practical horn antennas, PC location has significant variations with frequency leading to phase error loss and aperture efficiency reduction over the bandwidth of interest. To overcome this drawback, based on physical reasoning, shaped dielectric rods with appropriate excitation mode are designed and placed on the aperture of conventional rectangular and conical horn antennas. The simulation results show that using a shaped dielectric rod inside the horn antenna leads to a decrease in phase-centre variations versus frequency without disturbing the radiation pattern and reflection coefficient. To investigate the performance, a conical corrugated horn antenna loaded by a conical tapered dielectric rod is used as a feed of the transmitarray antenna. Using a shaped dielectric rod fabricated by 3D printing technology, the PC variations of the proposed horn decrease from 1.06 λ to 0.08 λ over the X-band (λ at 8 GHz). The measurement of the fabricated transmitarray antenna shows an improvement of maximum aperture efficiency from 55% to 64.7% at 10 GHz. The aperture efficiency bandwidth above 50% level is also increased from 1 to 2.2 GHz.