- Buyers Guide
The recent Roke Manor sponsored November ARMMS Conference in Corby UK, attempted and succeeded in breaking new ground at a juncture that the ARMMS chairman, Roger Hopper, described as, “interesting times”. To stimulate debate and attract a wider and more inclusive audience the program coordinator, Dominic FitzPatrick of Cardiff University, encouraged a greater mix of academic and practical papers and participation from younger members of the RF and microwaves community, with a number of students offering presentations.
The spectrum of papers was particularly wide and as always the delegates voted for the best paper presented over the two days. The accolade went to Keith Clark of Surrey Satellite Technology who showed photographs of small imaging satellites being launched from cold war silos by Russian ICBMs. These satellites produce very detailed images of the Earth’s surface, which necessitates a very high bandwidth downlink. He discussed the design of the 10 GHz power amplifier in detail, specifically the difficulties of non-linear modeling at X-band.
Even before receiving the best paper award Clark declared himself a fan of ARMMS, which is a voluntary, non-profit making organization that organizes two conferences a year. He said, "This has got to be the best value conference there is. You always walk away with a useful nugget of information or a good contact".
Other papers of note included one highlighting the WiFi activity in the 2.4 GHz license exempt band, which was presented by Adrian Wagstaff of MASS Consultants, who stated that preliminary results appear to show that congestion in the 2.4 GHz band can be successfully measured in a scientific manner by the use of portable monitoring equipment in the form of an ‘Internet Tablet’. He showed that on average utilization stood at around 10 percent, but that at some locations, such as Liverpool Street Station in London, the traffic was much higher. Analysis of the WiFi packet contents shows that at times 95 percent of packets are purely network ‘housekeeping’ packets, leaving only 5 percent for user data.
ZigBee, also operating in the 2.4 GHz band, was considered by Jonathan Harros of TRAC-KTL. As chairman of the ZigBee Qualification Group he was well placed to describe the detail of the system and in particular security aspects. The design of microwave components was addressed by a number of presenters. Liam Devlin of Plextek and John Birkbeck of Roke Manor looked at microwave mixers; Steve Cripps (Hywave Associates) analyzed the Doherty amplifier and Chris Roff (Cardiff University) the phenomenon of current collapse in GaN HFET transistors.
The design of a very low phase noise source was presented by Michel Chomiki of Temex who showed that, in the offset frequency range from 10k Hz to 1 MHz, the quietest source could be made from a SAW resonator. The significance of this frequency range was explained by the fact that radar systems are limited in their detection of objects by noise in that specific range.
The conference program was organized to enable the most effective interaction between speakers and delegates. There was also a technical exhibition that provided the opportunity for delegates to get hands on experience as well as the ARMMS dinner on the first evening, which provided a convivial and enjoyable networking environment.
To read detailed abstracts of the papers and to view details of the 2009 conferences visit: www.armms.org.