University of Queensland researchers have developed and successfully tested the first Australian - and one of the world's first - slimline mobile satellite antenna systems.
Operating on a shoestring budget, researchers in the Computer Science and Electrical Engineering Department have produced the first fully-planar antenna system which allows access to the Optus Mobilesat network.
The new antenna will be useful for emergency services, defence force personnel, travelling business people and for managing large fleets of trucks and aircraft.
The system, developed by head of the Department's Wireless Communications Group Associate Professor Marek Bialkowski and PhD student Nemai Karmakar, uses an antenna that is only 4cm high - the critical dimension - and 45cm in diameter.
Dr Bialkowski said testing showed the antenna, which could be vehicle-mounted, worked very well.
'The flat satellite antenna is much slimmer than any previous model, and its beam can be controlled in three dimensional coverage,' he said.
Dr Bialkowski said other Australian groups had obtained significant funds to develop antenna systems suitable for the Australia Mobilesat. However, their designs were not planar and antenna structures developed by these groups were at least 12 cm in height.
'The University of Queensland phased array is comparable in performance with prototype antennas developed by giant research laboratories such as NASA Jet Propulsion Labs in the USA and Toyota Central Research Labs in Japan, using millions of dollars,' he said.
'This system is a a triumph of ingenuity in the absence of funding.'
The University of Queensland prototype design uses low cost components - for example diodes that cost only 10 cents each - so researchers are confident it can be manufactured and brought to the market at a reasonable cost to consumers. Prototype components cost less than $100.
Dr Bialkowski, who has authored a book on antennas and associated systems for mobile satellite communications to be published in March, 1998, is currently visiting Nanyang Technological University in Singapore.
He said only five percent of Australia was covered by commercial mobile communications networks. Cellular mobile telephones could be used only in range of the nearest repeater tower, generally located along the coast or near major cities whereas the Optus Mobilesate network could serve the Australian continent and 200km out to sea with identical forms of service.
Previously, remote area travellers relied on high-frequency (HF) radio links, which were highly affected by climatic conditions, sometimes failing completely during heavy rain or sun spot activity.
The vehicle-mounted system advances previous designs developed by departmental researchers. A vehicle-mounted antenna developed several years ago in the department worked quite well but was rather bulky (70cm in diameter, 12 cm high and 22kg in weight), more suitable for mounting on a track or a train. It had 14 antenna elements of which three facing the satellite were electronically activated.
The new antenna can be placed conformally on to the roof of a passenger car.
'This is a phased array antenna with 12 elements arranged in two circles. During its operation, all the elements are activated. However, they are suitably phased so the total beam produced by the antenna is pointed towards the Optus B satellite,' Dr Bialkowski said.
Dr Bialkowski and Mr Karmakar have also developed a number of other 'smart' antennas, including an eight-element switched beam array, a four-element briefcase antenna for the same purpose of accessing the Australian Mobilesat system, and a seven-element switched beam GPS array for mining applications.
A graduate of the Bangladesh University of Engineering and Technology in Dhaka, Mr Karmakar completed a masters in electrical engineering at the University of Saskatchewan in Canada before migrating to Australia in 1992. He worked with Brisbane company Mitec Ltd for three years to develop various antennas for the Mobilesat network.
The Wireless Communications Group includes four senior academics, 13 PhD and seven masters candidates, and 20 undergraduates.
Its special areas of expertise are mobile satellite antennas and personal wireless communications.
'Over the past five years the research group has produced many breakthroughs in wireless and satellite communications. They include an innovative briefcase satellite phone, a 14-element switched-beam mobile electronic tracking satellite antenna, and high efficiency fixed-beam array antenna systems for reception of Direct Broadcast Satellite TV programs,' Dr Bialkowski said.
'We have some of the best research and development facilities of any university in Australia for microwave and high frequency projects.
'Last year we developed a new testing range as part of an upgrading of our facilities to take on substantial new research in areas as diverse as digital mobile phones, global low earth orbital satellites for receiving mobile phone communications, and passive microwave security cards.'
For further information, contact Dr Bialkowski, email: EMEbialko@ntu.edu.sg or Mr Karmakar, telephone (O7) 3365 4278, email: karmakar@elec.uq.edu.au
