Compensation of Antenna Misalignment Using Selection Diversity for Maritime Communications

Communication is essential for coastal and rural areas, and providing an alternative method of communication for isolated coves through maritime communications is a way to cater that need. In order to create a reliable communication system, antenna misalignment attributed to wave motion of the sea must be accounted for because losses in transmission and reception occur. The scope of this study covers the angular variation of wave motion, particularly the roll angle tilting an antenna experiences. In this paper, improvements of using diversity techniques for a 2.4 GHz communication link in the maritime environment were investigated. In particular, spatial diversity, which uses independent multiple antennas to achieve a level of performance one antenna could not, was employed. The use of selection diversity, a type of spatial diversity that selects the antenna branch with the best signal strength, to compensate antenna misalignment is considered and analyzed. A transmitter and receiver front-end incorporating selection diversity were designed and implemented. Results prove that the use of the proposed scheme increase the overall gain of the communication link. There is an average of 1.35 dB and 5.3 dB increase for 2 and 3 antennas respectively, in using receive diversity compared to no diversity, and an average of 2.4 dB increase in using 3 antenna transmit diversity as opposed to no diversity, all of which were exposed to continuous tilting conditions. The presented plots exhibit a general trend showing that selection diversity reduces the received signal strength fluctuations to lower power, and minimizes the losses due to antenna misalignment.