Channel characterization of EM waves propagation at MHz frequency through seawater

摘要

Electromagnetic (EM) communication is considered as a suitable physical layer choice for SeaWater. SeaWater EM communication presents advantages over acoustic and optical in shallow water and deep oceans. Theoretical analysis of EM wave propagation in SeaWater helps us to estimate maximum distance covered in SeaWater at multiple depth points up to 5500 m. Mathematics of EM propagation in SeaWater (conducting medium) shows dependence on f (Hz), is an element of (F/m), and sigma(S/m) of transmission medium. This paper presents channel characteristics of EM waves propagation at 1 to 20 MHz frequency through SeaWater based on real time data of SeaWater T(C degrees) and S(ppt) for averaged decades from 1955 to 2012 up to 5500 m. We estimated SeaWater sigma(S/m), is an element of(r) (F/m) (using Stogryns model), alpha (Np/m) (using Helmholtz model), Z(ohms), f(T)(Hz), v(p)(m/second), tau(second), and P-r(dBm) (using Maxwell equations and Friis law). Analysis of these parameters against multiple depths of SeaWater and frequencies shows that we can not assume constant sigma(S/m) (4), is an element of(r)(F/m) (81), f(T)(Hz) (888 MHz),v(p)(m/second) (3.3*10(7)), and tau(second) (8.2*10(-12)) for SeaWater. Estimated P-r(dBm) helped us to analyze that for lower transmission frequencies (means higher is an element of r) and for lower sigma(S/m), P-r(dBm) decays linearly. While for higher frequencies (means lower is an element of r) and for higher sigma(S/m), P-r(dBm) faces sudden exponential decay. That negates sudden exponential delay (in general) of P-r(dBm) in SeaWater; it was only possible by assuming constant SeaWater is an element of(r) (F/m) and sigma(S/m). Our paper illustrates radio frequency communication for SeaWater in 1 to 20 MHz range and also provides comprehensive performance analysis using MATLAB simulation tool.