Investigations into a wideband spatial beamformer employing a rectangular array of planar monopoles

This paper presents a rectangular array antenna with a suitable signal-processing algorithm that is able to steer the beam in azimuth over a wide frequency band. In the previous approach, which was reported in the literature, an inverse discrete Fourier transform technique was proposed for obtaining the signal weighting coefficients. This approach was demonstrated for large arrays in which the physical parameters of the antenna elements were not considered. In this paper, a modified signal-weighting algorithm that works for arbitrary-size arrays is described. Its validity is demonstrated in examples of moderate-size arrays with real antenna elements. It is shown that in some cases, the original beam-forming algorithm fails, while the new algorithm is able to form the desired radiation pattern over a wide frequency band. The performance of the new algorithm is assessed for two cases when the mutual coupling between array elements is both neglected and taken into account.

Enacting cultural diversity through multicultural radio in Australia

Australia is second only to Israel in being the world’s most culturally diverse nation, based largely on high levels of immigration in the second part of the 20th century. From the 1970s onwards, Australia formally recognized the massive social changes brought about by postwar immigration, and provided legislation to incorporate cultural diversity into everyday lives. One such ‘legislative’ enactment saw the establishment of multicultural broadcasting in Australia, as arguably a world-first, both in its comprehensiveness and diversity. Today, Australia has a public sector corporation, the Special Broadcasting Service, administering five radio services in 68 languages. Also, the Community Radio sector produces multicultural programming in 100 languages through a number of its 330 broadcast and 207 narrowcast stations. This article examines the relationship between radio and its communities. It argues that despite the ‘profile’ of SBS television, radio is much closer to its constituent communities, and therefore plays a greater role in enabling those communities to speak their own histories, beyond the confines of a consensual Anglophile paradigm.

Performance analysis of multi-radio AODV in hybrid wireless mesh networks

Wireless Mesh Networks (WMNs), based on commodity hardware, present a promising technology for a wide range of applications due to their self-configuring and self-healing capabilities, as well as their low equipment and deployment costs. One of the key challenges that WMN technology faces is the limited capacity and scalability due to co-channel interference, which is typical for multi-hop wireless networks. A simple and relatively low-cost approach to address this problem is the use of multiple wireless network interfaces (radios) per node. Operating the radios on distinct orthogonal channels permits effective use of the frequency spectrum, thereby, reducing interference and contention. In this paper, we evaluate the performance of the multi-radio Ad-hoc On-demand Distance Vector (AODV) routing protocol with a specific focus on hybrid WMNs. Our simulation results show that under high mobility and traffic load conditions, multi-radio AODV offers superior performance as compared to its single-radio counterpart. We believe that multi-radio AODV is a promising candidate for WMNs, which need to service a large number of mobile clients with low latency and high bandwidth requirements.