A Circular Beam-Steering Antenna With Parasitic Water Reflectors

In this letter, a salty water antenna with beam-steering characteristics is proposed. The antenna combines the idea of the electronically steerable parasitic array radiator (ESPAR) antenna and the water antenna to realize a 360° beam steering. The unique features of water antennas, such as transparency, reconfigurability, and liquidity, are fully utilized. Both the computer simulations and measurements are conducted to validate the performance. The proposed design has a frequency range from 334 to 488 MHz (S11 <; -10 dB), high radiation efficiency (>60%), 13 different working states, and a maximum gain of 5.8 dB. Compared with existing pattern-reconfigurable liquid antennas, this new antenna has a wider bandwidth, more working states, and better invisible ability. It is, therefore, a promising candidate for a range of very high-frequency or ultrahigh-frequency applications, such as Internet of Things and maritime applications.