Radiation Field Distribution above Sea Surface of Underwater Microstrip Antenna Array

Microstrip antenna has attracted extensive attention in the field of seafloor detection and underwater radar due to its stable structure and strong beam directivity. In this letter, the total-field scattered-field source finite-difference time-domain (TSS-FDTD) method with a simplified calculation method is considered to analyze the electromagnetic wave propagation generated by an underwater microstrip antenna (UMA). We analyze the field distributions of UMA, reduced-scale antenna and the two-element array composed of two UMAs. Meanwhile, the effects of element spacing and seawater conductivity on the radiation field distribution generated by the array are specifically studied, respectively. In addition, the scattering field of a metallic ellipsoidal target is analyzed. The simulations show that seawater can be used as the medium layer of the UMA in order to generate energy distribution in a near region similar to that of the conventional microstrip antenna. Furthermore, the element spacing for the underwater array should be adjusted based on the practical application.