Reducing and controlling the beamwidth of electrically small antenna arrays

As the size of wireless devices becomes smaller, there is a need for miniature arrays with narrow beamwidth. However these miniature arrays always have: (a) high reactive impedance, (b) strong inter-element coupling, and (c) wide beamwidth. In this work, we present an electrically small antenna array which is λ/10 at 400MHz that overcomes these challenges. Simulations show that a half power beamwidth (HPBW) of 28° is achieved. Our approach uses a reactive line for matching, and employs a parasitic element to reduce coupling between the array radiators. Concurrently, a biomimetic circuit is used to amplify the phase difference between adjacent elements (as close as λ/20 apart) to reduce beamwidth. Beamwidth control is also demonstrated by tuning the phase amplification circuit.