A Convex Optimization Approach for the Design of Supergain Electrically
Small Antenna and Rectenna Arrays Comprising Parasitic Reactively Loaded
AbstractA convex optimization formulation is provided for antenna arrays
comprising reactively loaded parasitic elements. The objective function
consists of maximizing the array gain, while constraints on the
admittance are provided in order to properly account for reactive loads.
Topologies with two and three electrically small dipole arrays
comprising one fed element and one or two parasitic elements
respectively are considered and the conditions for obtaining supergain
are investigated. The admittance constraints are formulated as linear
constraints for specific cases as well as more general, quadratic
constraints, which lead to the solution of an equivalent convex
relaxation formulation. A design example for an electrically small
superdirective rectenna is provided where an upper bound for the
rectifier efficiency is simulated.