Pattern-Reconfigurable Water Horn Antenna

A novel horn antenna realized by replacing the metallic walls with water walls is described in this paper. Through controlling the water flow in different layers, the proposed horn antenna based on a rectangular waveguide made of water walls can switch between its H-plane horn state and leaky-wave mode, which indicates reconfigurable radiation patterns. The energy bounding effects of a water layer are studied for choosing the suitable thickness and dielectric constant of the water walls. EHmn modes are excited and can propagate along the water waveguide. The E-field and H–field distributions of the EHmn modes are similar to the TE and TM modes excited in a metallic rectangular waveguide. Propagation constants of the EHmn modes have been extracted from simulation results and it is found that a leaky wave can be excited. Measured results show that the proposed water horn antenna has an impedance bandwidth (|S11| < -10 dB) from 2.5 GHz to 5.2 GHz (70.1% fractional bandwidth) for the H-plane horn state and from 2.6 GHz to 5.7 GHz (74.7% fractional bandwidth) for the leaky-wave state. Maximum gain of 11.8 dBi for the H-plane horn and 7.7 dBi for leaky-wave antenna are obtained. Due to the low cost, good radiation performances, transparent characteristic, and reconfigurability, this novel horn antenna may be potentially useful in future communication applications.