Research Seminar - Institute for Infrastructure Engineering

Title of the seminar: Performance Enhancement of Antenna Arrays for Wireless Structural Health Monitoring

Abstract of the seminar: Wireless sensing and monitoring has emerged in recent years as a promising technology that impacts the field of structural heath monitoring. The aim is to screen the performance of the structure and evaluate its health state wirelessly within a network in real time. Microwave antennas have played important roles in on-structure sensing systems. One antenna is required for wireless data communication whereas the others may be used as sensors and antennas for simultaneous sensing and communicating. The antennas/sensors can be used as wireless strain sensors embedded in or mounted on concrete or steel structures. However, for these applications both antenna gain and impedance bandwidth will be reduced considerably owing to the attenuation and scattering of electromagnetic signals in environmental media. This poor performance is regarded as the loading effect of media such as concrete on the antennas, and in turn, the wireless system suffers from significant transmission loss in its communication channels. To tackle such low-gain and narrowband problem, one of the potential solutions is to increase the antenna aperture size that collects more elements in a form of sequential rotation array (SRA). In this presentation the results of investigation into SRAs that composed of wideband circularly polarized (CP) antennas are considered. By nature, CP antennas transmitting signals on all planes, thus they have advantages over the linearly polarized antennas in terms of polarization mismatching, link establishment and multipath effect, etc. For a given number of antenna elements in an array, higher gain can be achieved by using larger element-spacing within a wavelength. However, high element-spacing gives rise to high sidelobe levels in both the co- and cross-polarizations. On the contrary, smaller element-spacing is suggested by wider pattern bandwidth, however, closely packed elements will produce strong mutual coupling that not just affects impedance matching but also CP performance. This presentation focuses on the issues of mutual coupling between wideband CP antenna elements in 2-by-2 arrays. The results determine a compromise between the achievable gain and the possible widest operation bandwidth of wireless monitoring system.

For catering purposes, please RSVP to r.stoddart@uws.edu.au by COB Monday 18 March 2013. Please advise if you have any special dietary requirements.