Kerans, Andrew, and Woods, Graham (2004) Observations of anomalous over the horizon microwave radio propagation inside the tropical maritime evaporation duct in North Queensland, Australia. Part One: normal ducting events. In: Proceedings of URSI Commission F Triennium Open Symposium 2004. pp. 1-6. From: URSI Commission F Triennium Open Symposium 2004, 1-4 June 2004, Cairns, QLD, Australia.

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Abstract

The evaporation duct forms over oceans due to rapidly changing humidity profiles immediately above the sea's surface. Evaporation ducts can trap propagating waves leading to increased radar ranges or an increase in interference from remote transmitters. 'Black holes' or areas of no target detection have also been observed in the presence of ducts and are predicted by simulation software. Much work is being undertaken on the characterisation of the evaporation duct above warm tropical oceans in Australia. This work is being carried out jointly by James Cook University JCU, Faculty of Engineering and the Australian Defence Science and Technology Organisation (DSTO).

Previous JCU work has established the average height of the duct and diurnal changes in the duct in various climatic conditions and seasons. Propagation at 10.6 GHz and 11.7 GHz over a 20-km path has been extensively measured in the past by the authors. This paper describes an experiment over a very long over the horizon path of 72.2 km at 10.7 GHz using a very low transmit antenna height (4 meters) and a receiving array ranging from 3.6 m AMSL to 11.7 m AMSL mounted on a platform 5.76 km out to sea at the end of a jetty.

In part one of this paper we present some results which verify results from theory and simulation packages used in this research, In part two we look at some different results for which we do not have a full explanation. In both cases an analysis of received signal strength along with general weather conditions is presented. Finally conclusions are drawn for the implications and applications of anomalous propagation within the evaporation duct.

Item ID:	27121
Item Type:	Conference Item (Research - E1)
ISBN:	978-0-646-43423-0
Keywords:	evaporation duct; radio propagation
Related URLs:	http://www.ursi.org/en/commission.asp
Date Deposited:	16 Aug 2017 04:01
FoR Codes:	10 TECHNOLOGY > 1005 Communications Technologies > 100599 Communications Technologies not elsewhere classified @ 70% 09 ENGINEERING > 0911 Maritime Engineering > 091199 Maritime Engineering not elsewhere classified @ 20% 09 ENGINEERING > 0906 Electrical and Electronic Engineering > 090699 Electrical and Electronic Engineering not elsewhere classified @ 10%
SEO Codes:	81 DEFENCE > 810108 Navy @ 51% 89 INFORMATION AND COMMUNICATION SERVICES > 8901 Communication Networks and Services > 890199 Communication Networks and Services not elsewhere classified @ 49%
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