A Novel Beam-Switching Array Antenna Using Series-Fed Slots With PIN Diodes

A novel slot array is proposed for uses on femtocells of mobile services. The array contains multiple sets of equally spaced slots connected in series on a coplanar waveguide. A diode-loaded shorting strip is mounted across each slot to enable or disable radiation so that switchable beams of different tilting angles can be provided. The proposed design comes as a flat panel hanging on the wall. The beam direction of this base station antenna can be set to yield an appropriate coverage depending on user equipment locations. A two-state prototype was fabricated to demonstrate the feasibility of this approach. Measured down-tilt angles are 13° and 32°, respectively. The 3-dB beamwidths are approximately 25°. The proposed structure can be configured to achieve versatile performance features. A design of low sidelobe levels as well as a three-state design is devised. Discussions about slot excitation, line termination, and diode biasing circuitry are also provided.