Co-Design of Dielectric Resonator Antenna and T-Shaped Microstrip Feeding Network for Back-Radiation Suppression

In practice, the broadband feeding network on the back side of an antenna can have a nonnegligible effect on the antenna's back radiation due to the feeding network's radiation contribution. Thus, a back-radiation cancellation scheme is proposed by co-designing the antenna and its feeding network to solve this problem. The antenna and its feeding network can be viewed as a two-element array. Their radiation toward the antenna's backward direction can cancel each other when both have equal amplitude and opposite phases along the back direction. A differential fed dielectric resonator antenna (DRA) through a rat-race coupler (<inline-formula><tex-math notation="LaTeX">${180}^\circ $</tex-math></inline-formula> hybrid coupler) and a T-shaped broadband differential feeding network are compared and analyzed to verify the proposed scheme. In addition, a <inline-formula><tex-math notation="LaTeX">$1\!\times\!4$</tex-math></inline-formula> DRA array with a T-shaped broadband differential feeding network in a previous work (where the feeding network's radiation effect on the back side was overlooked) is used for experimental validation of the proposed scheme. Simulations and measurements demonstrate significant back-radiation suppression than the ideal differential feeding network.