Use this URL to cite or link to this record in EThOS:
Title: Underwater communication using electromagnetic waves
Author: Yip, Chun Keung
ISNI:       0000 0001 3575 3019
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2007
Availability of Full Text:
Access from EThOS:
Access from Institution:
This project was to investigate the EM waves for transmission in seawater with a varied frequency from about 1 MHz up to 40 MHz. Trials were carried out in the laboratory tank, the Albert Dock and the Loch Linnhe. Standalone transmitter and receiver units were constructed for performing the experimental trials. A receiver is used to pick up the signal from the transmitter and the signal was analysed using ,a spectrum analyser. Frequency can be varied outside the transmitter from a lap top by using an optical fiber. Different types of antennae were built and tried in the experiments. In the Albert Dock, the results have shown that EM waves in the range of 1 to 5 MHz is possible to propagate about 100m using a 30W power amplifier. A new antenna design was developed and investigated in the laboratory tank. Results have shown that there is about 30dB gained by implementing the new antenna design. The signal strength can be further improved by 10 dB when the antenna and the signal generator were matched at 10MHz. In the near field, EM waves suffer from high attenuation in seawater but have a low attenuation in the far field. This is due to the generation of EM waves by dipole oscillations of the water molecules within the antenna field which can be used to explain results obtained from trials.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral