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Industry News

Second Harmonic Clipping Contour and new Smith chart to be presented at the RF & microwave conference

October 7, 2013
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Radio frequency power amplifier design requires the correct termination of all harmonic frequencies. Tim Canning of Cardiff University will explain how the ‘Second Harmonic Clipping Contour' concept has been developed to visualise the impedance region that prevents the drain current falling to zero, and so enable an optimum design. He will explain the use of the tool as part of the PA design process at the forthcoming RF and Microwave conference. A 10 W GaN demonstrator gives measured CW power > 8.5 W, drain efficiency >60%, and better than -30 dB ACPR over a bandwidth of 1 to 2.9 GHz.

The Smith chart is 74 years old so a makeover is required according to Andrei Muller of Grupo de Aplicaciones de las Microondas. Does mapping the surface of the Smith chart to the Northern Hemisphere of a globe seem a good idea? Well yes, as it allows the Southern Hemisphere to represent reflection gain caused by active devices. Perfect unity reflection co-efficient is at the equator and the angle of reflection co-efficient corresponds to the latitude. Zero degrees longitude at the equator is an open circuit and for inductance go east. Andrei will explain the benefits of his 3D Smith chart at the RF and Microwave conference.

A paper from EMISENS will also address the very rapid detection of liquid explosives in sealed containers for use at airports. Norbert Klein will explain how the evanescent mode field of a multimode cavity can be used to observe the complex dielectric constant of liquids on a routine basis.

V-Band (50 to 75 GHz) and W-Band (75 to 110 GHz) receive attention from two authors. William Otter of Imperial College London will discuss photonic crystal devices and shows how very high Q structures can be created in monolithic integrated circuits in W-Band. Liam Devlin of Plextek RFI and TriQuint Semiconductor will describe a low cost GaAs PHEMT amplifier for the 54 to 67 GHz frequency band.

The ARMMS RF and Microwave conference is to be held over the two days of Monday 18th November to Tuesday 19th November 2013 at Wyboston Lakes, Wyboston, near Cambridge, UK. The associated exhibition provides facilities for demonstrations of microwave technology and has proved a very effective networking opportunity. To book a place, go to To present a paper contact the programme co-ordinator Stepan Lucyszyn of Imperial College, London

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