Analysis of On-Antenna Power Combining for Realization of Pattern-Reconfigurable Multifeed Microstrip Antennas
Sirous Bahrami, Dongseop Lee, Wonbin Hong, Ho-Jin Song
Abstract
This article explores an on-antenna power combining concept for multifeed microstrip antennas. We incorporated different radiation modes of multifeed antennas, thereby optimally exploiting the given space of a single radiator. The analytical cavity model is revisited to facilitate analysis of the on-antenna power combining mechanism in planar topologies. The analytical modeling is first aimed to apply to conventional patch structures and offers an in-depth design methodology. As the analytical method is facing limitations in irregular-shaped antennas we proposed a reliable and computationally cheap numerical method based on the eigenvalue analysis of the scattering matrix. The proposed method can be used to extract the optimum excitation and impedance of each port of resonant-type multifeed antennas. Due to the proposed numerical method, one can examine the excitation vector and the active impedance values for different radiation modes of multifeed antenna concurrently. Next, the reliability of the solutions of the proposed numerical method is evaluated against the analytical solutions through some examples. A multifeed structure not only can furnish on-antenna power combining but also assist with tailoring reconfigurable antennas. Finally, a practical planar radiator topology featuring multifeed excitations exhibiting a high-gain reconfigurable antenna with sum and difference patterns is devised.