Measurement of wideband microstrip underwater antenna performance with buffer layer structure

Underwater wireless systems require optimized antennas to realize high data rate transmission. Conventional antennas performs poorly underwater since they are originally designed to radiate electromagnetic waves through the atmosphere. This paper presents a wideband underwater antenna utilizing buffer layer structure for performance enhancement. Optimization of the buffer layer parameters such as dielectric constant and size, improved the antenna return loss a wide bandwidth when operating underwater. Simulation results showed the best performance when using dielectric constant value calculated by the geometric average among air and the transmission medium, and buffer layer size equals to the radiating near field region of the antenna. This design concept was verified through actual measurement using an in-house synthesized buffer layer material, in an indoor laboratory water tank. The measured fractional bandwidth is 79 % (250 to 645 MHz), which is notably attractive for high data rate underwater applications.