A method for matching parasitic unidirectional electrically small array

General design guidelines for unidirectional electrically small parasitic array has been proposed by several researchers; however, the input resistance of these antennas is normally very low. In order to practically “convert” this high directivity into realized gain, an appropriate matching mechanism is necessary. This paper gives a simple matching method by adding an inductive stub close to the antenna feed, which can effectively increase the antenna input impedance to 50 Ω and keep the gain almost invariant. Besides, it could make the resonant frequency very close to the frequency where maximum gain occurs, thus a high realized gain can be achieved. Computed and measured examples are given to validate this method.