Armms RF and Microwave Society
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Conferences

Monday 24th April to Tuesday 25th April 2006 at Milton Hill House, Steventon

Review of the ARMMS RF and Microwave Society conference held on Monday 24th April to Tuesday 25th April 2006 at Milton Hill House, Steventon near Oxford in the United Kingdom. Chairman George Hjipieris of NERA Networks AS opened the conference by encouraging a discussion on the merits of and applications for ?on-chip? RF prototyping. A technique for the ?on-chip? wiring up of very high performance vertical MOSFET RF devices was presented by Alec Reader of Innos, which did indeed lead to a lively discussion. The prospect of very high Q resonators created by electron beam wiring, leading to very good phase noise oscillators was noted. Precision measurements in the 75GHz to 110GHz frequency range were presented by Jimmy Yip of the UK?s National Physical Laboratory. He showed that the random errors that result from the repeated physical connection of wave-guides was substantionally less for dielectric wave-guides based on polypropylene when compared to metal wave-guide. More accurate calibration of return loss in the range to 325GHz is ultimately expected as a result of this work. Sources of galactic noise were explained by David Farm of the British Astronomical Association?s Radio Astronomy Group. In particular it was explained that Doppler shifts of the order of 5kHz can be observed in the weak, but readily detectable radiation originating in the adjacent spiral arms of our home galaxy. The design of a receiver for the 1.42GHz hydrogen line was illustrated and the integration of this receiver into an Internet based array of receivers called ?The Starbase Plug and Play Observatory? explained. Ben Allan of Oxford University provided a very clear picture of the current state of Ultra Wide Band (UWB) technology. He went on the explain how the characteristics of antennas such as the ?disk cone? may have very broadband match characteristics but vary widely in radiation pattern over the 3GHz to 10GHz UWB range. The propagation characteristics of these antennas in a room, were presented in animated form which impressed the delegates, and resulted in Ben winning the Best Paper prize. The secrets of the manufacture of wave-guide filters that require no tuning through to 50GHz, were presented by Eric Wheatley of NERA. Methods of obtaining high efficiency and good linearity in power amplifiers were explained by Steve Cripps of Hywave Associates. Intrigued ? Papers presented at the conference are available on the web at www.armms.org ? or even better attend the next conference, which will be held in the UK in November. Many opportunities for informal discussions arose at the ARMMS RF and Microwave Society dinner, which was held on Monday evening. The Milton Hill House conference centre provided accommodation and informal chat on many matters continued until the early hours. Steve Maas of Applied Wave Research began the Tuesday programme by explaining the effect of adding resistance to the base or emitter of individual HBTs in a parallel array, to obtain thermal stability and avoid current ?hogging?. A very detailed analysis showed that the optimum solution could depend on the type of modulation to be amplified. Papers by Micah Li of Flowmerics and Mohan Jayawadene of CST looked in detail at E-M modelling of a variety of structures including complete ships and frequency selective surfaces (FSS). A new short name for FSS appears to have been coined: ?Stealthy wallpaper?. The topic of behavioural modelling of complete radio systems was addressed by Graham Reith of MathWorks who also coined the term ?Model-Based Design?. He explained that the partitioning of the various technologies in a radio system: RF, analogue, FPGA and executable code; can be optimised by these techniques. The effect of spectacles and jewellery on specific absorption rates (SAR) by RF energy from mobile phones, was considered by Rob Edwards of Loughborough University. He showed, by both experimental methods and EM simulation, that these metallic objects do have some effect on SARs although he declined to provide guidance on the most fashionable style of jewellery to be worn. The calibration of static magnetic fields as produced by the permanent magnets within isolators and circulators was addressed by John Dudding of Hirst Magnetic Instruments Ltd. In a very clear lecture he explained how the automatic reduction in magnetisation from saturation is achieved, leading to higher quality products. Instrumentation was not neglected by the conference; Gary Swinton of Tektronix explained how Real-Time Spectrum Analysers (RTSA) provide a real advance in the display of modern complex signals. Neil Thomas of Aeroflex presented detailed information on the design of a PXI based broadband down-convertor and digitiser to 6GHz. In a ground-breaking paper, Nick Long of Great Circle Design described a standardised method of measuring radio system immunity to interference. The method automates a process that would otherwise take many days, and displays the results in a form of a ?well diagram?. This diagram captures a huge amount of information and characterises the ability of a receiver to operate in the presence of interfering signals. As the radio spectrum becomes yet more congested this work is likely to become yet more relevant. The conference concluded with George thanking Tony Chapman Electronics who provided sponsorship, and JJ Heath-Caldwell who is stepping down from the position of Marketing Co-ordinator for ARMMS after six years of successful efforts. Duncan McIntosh has agreed to take this role for the next conference which takes place on 6th and 7th of November 2006. The society thanks Simon W Day of Phasor Design ? www.phasor-design.uk.com for his efforts in co-ordinating this very succesful meeting. 26th April 2006

VENUE

Milton Hill House
Milton Hill
Steventon
Oxfordshire
OX13 6AF

Tel01235 831 474
Fax01235 825 796
Emailmiltonhill@initialstyle.co.uk
Webwww.initialstyle.co.uk

PROGRAMME CO-ORDINATOR

Simon W Day
Phasor Design
4 Malborough Way
Market Harborough
Leicestershire
LE16 7LW
United Kingdom
web: www.phasor-design.uk.com

Tel+44(0)1858 432148
Emailswd@phasor-design.uk.com

PAPERS

3-D EM Simulation of Infinite Periodic Arrays and Finite Frequency Selective Horns

Mohan Jayawardene & Yiannis Vardaxoglou
CST & Loughborough University
Frequency Selective Surfaces (FSS) are predominantly passive electromagnetic filters formed by thin conducting elements on a dielectric substrate or periodic aperture elements in a conducting sheet. Depending on the type of elements (conducting or apertures), they exhibit bandstop or bandpass properties when excited with an incident electromagnetic wave. These filtering properties of FSS have been successfully utilised in curved FSS antenna systems as FSS sub?reflectors, radomes, Frequency Selective Guides (FSG) and Frequency Selective Horns (FSH). The most common analysis is the unit cell based approach using the Floquet modes, well suited for infinite planar arrays. However, arbitrarily curved or finite surfaces present greater problems because of the numerical complexities and the intricacies in modeling 3-D structures. In a curved array, it becomes necessary to perform the computations for groups of elements or individual elements conformed to the profile of the full 3-D structure. In this paper a finite conical FSH antenna consisting of conducting elements on a dielectric substrate modelled using the CST MICROWAVE STUDIO? (MWS) is presented. The full 3-D EM simulation tool is based on the Finite Integration Technique (FIT). The versatility of FIT allows for problems to be formulated on a Cartesian (Hexahedral) or general non-orthogonal (Tetrahedral) grids both in the time domain as well as the frequency domain. Initially, the frequency domain solver using the full Floquet modal expansion and periodic boundaries was used to calculate the resonant frequency of the unit cell. The time domain solver using the hexahedral mesh with a finite conductor thickness and the frequency domain solver with a tetrahedral mesh with zero thickness metal was used to model a conical FSH for comparison.
3-D EM Simulation of Infinite Periodic Arrays and Finite Frequency Selective Horns

A Low-Budget Harmonic Load-pull System for High Power Amplifier Design

Steve Cripps
Hywave Associates
Empirical techniques continue to play a much bigger role in RF design than most care to admit. The PA community however still embrace measurement-based characterisation and design, especially when the power becomes ?high?, which above 2GHz means anything above a few watts. This paper will review the various load-pull techniques, including both active and passive approaches, for the design of efficient, linear RF PAs. A low cost system will be described which enables real-time, independent impedance control at fundamental and harmonic frequencies, something which commercial manufacturers have struggled to achieve. Some measurement results will also be presented.
A Low-Budget Harmonic Load-pull System for High Power Amplifier Design

Automatic magnetic calibration of microwave isolators and circulators

John Dudding
Hirst Magnetics
Many areas of manufacturing in Microwave devices have seen significant improvements and increased efficiencies in production, yet the magnetic calibration ( also know as Demagnetisation, Setting or Treating) has remained a manual operation based upon low capital cost magnetic equipment. The talk will cover the basics of magnetics, magnetic calibration and the dramatic improvements in production rates, quality and economics that can be achieved with modern automatic magnetic calibration* equipment. (* also known as Setters, Demagnetizers or Treaters ).
Automatic magnetic calibration of microwave isolators and circulators

Ballasting of HBTs For Wireless Power Amplifier Operation

Steve Maas
AWR
This paper describes ongoing work to evaluate conditions for bias stability in large power devices, with particular emphasis on the interplay between thermal stability and electrical performance. We begin by reviewing the need for ballast resistance in power devices, and show how current instabilities occur. We then show that the conventional wisdom concerning base ballast in HBTs is correct; that is, it generally provides good thermal stability, but only if appropriate levels of ballast resistance are used. Conversely, we show that emitter ballast, while providing less robust thermal stability, provides better RF performance and thus may be preferable for many applications. The values of base and emitter ballast resistance required for good RF performance are surprisingly high.
Ballasting of HBTs For Wireless Power Amplifier Operation

Design and Production of Low-Cost Metallized Polymer mm-wave Components

Eric Wheatley
NERA
The design and production of high precision, mm-wave waveguide components using injection molded and metallized polymers have been investigated as a possible way to reduce the cost of high volume consumer satellite terminals operating in the 20-30GHz range. Based on this experience, the issues of electrical design for molding, polymer selection, molding, and metallization are discussed as they relate to tolerances and yield, surface quality, thermal stability, and overall electrical performance of feedhorns, OMT, and filters. The accuracy and cost limits for this approach are briefly discussed.
Design and Production of Low-Cost Metallized Polymer mm-wave Components

Design of a Broadband Downconverter / Digitiser in a PXI Module

Neil Thomas
Aeroflex Test Solutions
This paper describes the design and implementation of a 6GHz extension to a 3GHz RF digitiser in PXI technology. The features of the PXI format that affect the design are considered. The available RF design options are discussed, and the final design solution is presented, with results.
Design of a Broadband Downconverter / Digitiser in a PXI Module

Fabrication and characterisation of vertical MOSFETs & RF CMOS

Alec Reader
Innos
This presentation will address some methods of manufacturing high performance but low cost transistors and integrated circuits (ICs). The presentation will focus on RF-CMOS ICs. Conventional Transistor and IC fabrication is heavily dependent on very many sequential precision manufacturing steps which consequentially lead to long manufacturing cycle times. Additionally equipment and infrastructure costs make IC manufacture very expensive. New ICs are developed from original circuit designs. From the circuit design to a working product requires a number of iterative manufacture steps during which prototype circuits are manufactured and tested. Failure of a prototype followed by identification of the failure mode leads to an improved circuit design and the requirement for the manufacture of further prototypes. This whole reiterative process for prototype manufacture can frequently take more than one year, which can make the original design out dated. Methods will be discussed which drastically decrease this fabrication time, and thus cost, particularly for prototype production.
Fabrication and characterisation of vertical MOSFETs & RF CMOS

Immunity From Airborne Agents

Nick Long
Great Circle Designs
Any radio system can be disrupted by interference. The end user naturally expects a reasonable degree of interference immunity in the design. In many cases, though, there is no definition of what is reasonable and no agreement on test methods. The interference performance of radio equipment sold to non expert customers can range from downright negligent to surprisingly good. This paper reports on development of standardised and automated test methods for short range telemetry links. Results obtained from several commercially available devices are presented, showing a wide variation in the ability to reject interference.
Immunity From Airborne Agents

Measurement of Ultra Wide Band Wireless Channels

W.Q Malik, B Allen, D.J Edwards
Department of Engineering Science, University of Oxford
Ultra-wideband (UWB) wireless systems are currently touted as a wire replacement technology and sensor network solution. Fundamental differences exist between the behaviour of conventional and UWB antennas and propagation channels. This paper presents a measurement technique for obtaining UWB antenna element and propagation channel characteristics. A selection of results are also presented and features that differentiate these from those of conventional wireless systems are shown.
Measurement of Ultra Wide Band Wireless Channels

On the question of whether to model or measure the levels of RF energy from mobile phones into the head

Dr Rob Edwards
Centre for Mobile Communication Research, Dept. EEE, Loughborough University
In recent years antenna engineers have brought their inventions ever closer to the human head. As a result concerns have surfaced about what effect radio frequency energy at the levels produced by mobile phones might or might have on the human brain. Since these devices are very popular, the subject can emotive and is its study is complex since it is extremely difficult to measure anything within a living head. Our work at Loughborough University seeks to establish the relative RF energy levels in parts of the head, particularly the eyes, due to mobile phones, spectacles and jewellery. This paper discusses and contrasts the two major disciplines in this area of research, namely measurement of representative physical phantoms (solution filled heads), and analysis of complex mathematical data based upon MRI and other useful sources in modelling.
On the question of whether to model or measure the levels of RF energy from mobile phones into the head

Simplified radar measurements with real time spectrum analysis

Gary Swinton
Tektronix
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Simplified radar measurements with real time spectrum analysis

Starbase and the Plug and Play Observatory Project

David Farn
BAA RAG
The British Astronomical Association Radio Astronomy Group exists to encourage and give practical assistance to amateur radio astronomers in the study of astronomical phenomena at the lower end of the electromagnetic spectrum. Starbase is a proposal to provide a common platform for group observing programmes and sharing of resulting data via the Internet. The group is developing software to manage a central data repository and to provide remote display of the output from on-line radio telescopes operated by its members. The Plug and Play Observatory project seeks to make hardware and software available to those wishing to build and operate a radio telescope that can then become part of the Starbase network. Current projects include receivers operating between 20KHz and 2.7GHz and linkage to a Starbase enabled 151MHz receiving array, operated at the Mullard Radio Astronomy Observatory (MRAO), Cambridge. The main challenge for the group is the development of viable designs that can be manufactured in limited quantities.
Starbase and the Plug and Play Observatory Project

The efficient EM modelling of electrically large strutures

Micah Li
Flomerics
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The efficient EM modelling of electrically large strutures

Towards a New Form of National Impedance Standard for Millimetre Wavelengths using Dielectric Waveguide

Jimmy G. M. Yip(1), M-H John Lee(2), Nick M. Ridler(1), and Richard J. Collier(2)
(1) National Physical Laboratory, Teddington. (2) Microelectronics Research Centre, Cavendish Laboratory, University of Cambridge.
For RF and microwave measurements, UK national impedance standards are currently available using coaxial lines to 50 GHz and metallic rectangular waveguide to 110 GHz. At present, no standards exist above these frequencies. Therefore, a new form of impedance standard (utilising dielectric waveguide) is currently being investigated for precision metrology applications across the entire millimetre-wave band (i.e.extending to at least 300 GHz, and perhaps beyond). This paper reports on the progress to date with this work.
Towards a New Form of National Impedance Standard for Millimetre Wavelengths using Dielectric Waveguide

Using Behavioural Models to Drive RF Design and Verify System Performance

Graham Reith
MathWorks
A new generation of software tools for Model-Based Design is enabling the creation of system-level models that system architects can use to evaluate the RF design specification. Before, during, and after the design of the circuitry for the components and modules, the same system-level model can incorporate ever more refined performance information in order to determine the impact on system-level performance. This new approach makes it possible to find and fix system-level problems much earlier in the design cycle, when they can be quickly and inexpensively corrected. It also lets engineers evaluate a wide range of alternative designs to optimize performance, cost, and power consumption.
Using Behavioural Models to Drive RF Design and Verify System Performance


CALL FOR PAPERS

Contributions are invited with an emphasis on RF and microwave design, research, testing and associated subjects. An oral presentation will be made at the meeting and a written paper will be required for publication in the society digest, which is distributed to delegates at the meeting. Prospective speakers are requested to submit a title and a short abstract to the technical coordinator (see above) as soon as possible.

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