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Military Microwaves Supplement
Recent Advances in Radar Technology
Using Calibration to Optimize Performance in Crucial Measurements
Micro-particles, Differential Evolution (DE) and developments in Gallium Nitride (GaN) technology were the highlights of the APC Novacom sponsored November ARMMS conference, which was held in Corby, UK, on 22 and 23 November. Of the 14 papers that were presented, the one titled, Improved infrared temperature measurement of RF devices, given by Dr. Richard Hopper of De Montfort University, Leicester, UK, gained the attention and the votes of the attendees to earn him the Steve Evans-Pughe Prize for best speaker.
Hopper illustrated how the standard methods of assessing temperature in AlGaN/GaN high electron mobility transistors could be in error. Infrared thermography has advanced to be capable of 3 μm resolution, but can give misleading results due to emissive and transparency issues. The presentation set out how this defect is resolved by the use of a 3 μm amorphous carbon micro-particle placed on the gate region. The thermal image of the particle indicates the correct temperature of the underlying channel.
Alex Scarbro of Linwave Technology focused on Differential Evolution – a newly developed optimization technique, which has been applied to multi-octave amplifiers. He described the use of the DE algorithm to effectively find the optimum set of fundamental power and injected second harmonic amplitude and phase, for best power efficiency. The algorithm is well suited to simple computation and Scarbro described an automated test equipment system based on this technique.
GaN technology was covered by a number of speakers. David Seymour of EADS Astrium described reliability testing studies on solid state power amplifiers for satellite application including Heavy Ion testing. Chris Harris of Cree Inc. showed how very wideband amplifiers maintained very good noise figures when fabricated in GaN.
Terahertz wave measurement was discussed by Mira Naftaly of NPL. She described the use of the ‘etalon’ to calibrate terahertz frequency in free space. The etalon is made of a polished undoped silicon wafer, and produces a transmission spectrum of regularly spaced peaks and troughs useful for calibration of both frequency and amplitude.
The varied conference program, which was compiled by Keith Clark of Surrey Satellite Technology, attracted 61 delegates, an increase on the last meeting in April 2010. It was supported by a table top exhibition, where Agilent Technologies, Anritsu, APC-Novacom, Atlantic Microwave, AWR, Flann Microwave, Libra Design, Linwave Technology, Livingston Hire, NTK Technical Ceramics, Microwave Marketing, PoweRFul Microwave and SJ Technologie not only showcased their products, but also provided a platform for networking.
As well as a vehicle for finding out about the latest technology and networking, the ARMMS Conference is also a social event, with a dinner on the first night offering delegates, presenters and exhibitors the opportunity to mix business with pleasure. Wide ranging discussions continued until late in the evening and were not strictly limited to technical topics.
Guy Purchon of Anritsu, Treasurer of ARMMS, closed the conference by thanking the speakers and reminded the delegates that the next meeting will be in Oxford, UK, on Monday 4th and Tuesday 5th of April 2011. The program coordinator will be Alistair Frier of Teledyne Labtech. Those interested should visit www.armms.org to offer a paper and book a place.
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