viernes, 28 de mayo de 2010

Christopher Bartram RF Design

Chris Bartram has a lifetime's experience of radiofrequency circuit design, gained largely while working as an independent consultant. This breadth of experience allows him to look creatively at engineering problems, and provide novel and cost-effective solutions.




  • Skillset
Chris is fundamentally a circuit designer, although he sometimes finds it difficult to draw a line between systems and circuits! In recent years, much of his energy has been directed into a number of 'difficult' areas associated with modern high performance transmitter and receiver design:

  • Power amplifier design. From mW to kW. Applications have included instrumentation, CDMA, TETRA, AM and digital airband (VDL) services, SSB and constant amplitude modulation schemes to several GHz. This has included the application of broadband technologies with multi-decade frequency respose and the development of physical designs using modern materials, devices and manufacturing techniques to produce highly competitive and reproducible products. 

  • Transmitter linearisation technologies. Chris has been involved in complex feedback linearisation techniques (on-frequency feedback, IF feedback, and cartesian feedback), and predistortion.

  • Digital and analogue transmitter design. The implementation of transmitters in the digital domain, and particularly techniques for economically integrating linearisation technologies into medium bandwidth transmitters employing digital technology is of considerable interest. Areas of expertise in the analogue area include low-noise transmitter design. 

  • Receiver Design. Particularly high linearity and low-noise receiver front-end design. Chris has had a substantial interest in this area for decades, and has an armoury of techniques at his disposal.

  • Frequency synthesiser design. Including mixed DDS/phase-lock synthesis, fractional-N synthesisers and oscillator design.

  • Antenna Design. Although not fundamentally an antenna engineer, Chris has considerable experience of antenna design, especially the design of efficient compact antennas integrated into equipment.

  • Digital design. Although Chris has experience of digital design, it is not a strong point and he does not offer it professionally. However, he has extensive contacts with digital hardware, software and DSP specialists, and can usually suggest links to experts within these fields.

  • Lecturing. Chris has lectured on post-graduate/CPD courses in RF Design at the University of Essex, for the Low Power Radio Association, Radio Frequency Investigation Limited and the Institute of Printed Circuits.

  • Other areas of interest have included Low Power Radio design, and industrial uses of RF technology and support to the scientific community.
CBRFD is always happy to consider the design of one-of-a-kind projects, and to provide complete turnkey solutions for very short run and one-off experimental projects.


  • Facilities
CBRFD has very adequate lab. facilities. The equipment available includes spectrum analysers, vector network analysers, high-performance signal generators, and sweeper, noise figure measurement sources and receivers, instrumentation power amplifiers, power-meters and digital millivoltmeters. There is also a good selection of passive RF devices including stub and slug tuners, couplers, power and precision attenuators, and loads up to 2.5kW. Measurements can be made at thermal extremes. Much of the equipment is is IEC625/IEEE488 linked.

CBRFD is also fortunate to have more than adequate open-site antenna and EMC test facilities, with a purpose-built 20 x 40m open-air test site. This is complemented by several additional acres of suitable land.

Computing facilities are based on a group of hetrogeneously networked MS Windows and Linux machines with firewall and up-to-date anti-virus protection. A mix of proprietary (Agilent/Eagleware Genesys, Protel, B2 Spice, NEC4WINVW, EZNec, Sonnet, Mathcad) and Open-Source (Open Office, QCad, Kicad, MuPAD, and GNU Octave - an Open Source application capable of running MATLAB scripts) software provides maximum flexibility. Outputs to customers are provided in standard formats (*.pdf, *.doc, *.xls, *.dxf, Gerber/RS274X etc.) wherever possible.

CBRFD is located near Carmarthen in south-west Wales in an RF quiet, rural environment. Fast modern roads are less than 10mins away. Travel times are typically 1hr 45min to the Severn Bridge, 3hrs to Reading, and Birmingham, and 4hrs to London. A wide range of domestic and international flights are available to Cardiff and Swansea.

Publicado por: Jahir Alonzo Linares Mora
C.I: 19769430   CRF

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