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Dr Jonathan Lees

Dr Jonathan Lees

Senior Lecturer

School of Engineering

Email
leesj2@cardiff.ac.uk
Telephone
+44 (0)29 2087 4318
Campuses
E/3.11
Users
Available for postgraduate supervision

Overview

My key research areas are linear-efficient PA design and microwave characterisation with a specific interest in the design and optimisation of High-Efficiency Power Amplifiers. Significant achievements include the first published GaN Doherty amplifier, and more recently, activities considering the development of novel high-power, broad-band time-domain measurement and load-pull techniques that directly address the current and future needs of modern communication systems.

My most recent research activities include developement of compound semiconductors devices and circuits for high-frequency electronics, mm-wave characterisation, investigating RF properties of materials, microwave heating and disruption and application of microwave engineering to healthcare and diagnostics.

Biography

I began my career in 1998 developing optical and GPS-based positional tracking solutions with QinetiQ, U.K. and became a chartered Engineer in 1999. I obtained my MSc. and PhD. degrees from Cardiff University in 2002 and 2006 respectively and joined the Centre for High Frequency Engineering (CHFE) as a Research Associate in June 2005. I became a Lecturer in 2011 and then in 2016, a Senior Lecturer in Non-Linear Microwave Characterisation. Between 2009 and 2010, I was seconded to Mesuro as a Senior Hardware Engineer.

My current  academic roles include Head of Department for Electrical and Electronic Engineering, as well as Year-4 MEng Tutor. Previous roles include  Director of Taught Postgraduate programmes for Engineering, Year-1 Tutor for Integrated and Electrical and Electronic Engineering and Director for the Wireless and Microwave Communications Engineering MSc and its variants.

My research focus is developing non-linear microwave measurement and characterisation capabilities, high-performance microwave amplifiers, as well as the study of device non-linearity and linearization using modulated time-domain and envelope domain techniques. My work in this area culminated in the first published GaN Doherty amplifier, and more recent activities consider the development of novel high-power, broad-band time-domain measurement and load-pull techniques as well as dynamic supply modulation techniques in achieving high efficiency and high linearity in microwave power amplifiers. Over recent years I have applied my microwave expertise to medical and other applications, including the design of highly integrated microwave power amplifiers for diagnostic applications, and the generation and use of high power pulsed microwave energy for the detection of clostridium difficile.

I currently supervise / co-supervising over 10 PhD students in Microwave Engineering and related fields. I represented Cardiff University (founder member) in the European EUREKA OperaNET-2 programme driving down power consumption in mobile communications system networks.

Honours and awards

In June 2018 I was awarded the Cardiff University Business Innovation award for work with a local company developing low-power autonomous load-cells.

EEE Teacher of the Year award – EN3082/782 – 2016/17

Publications

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Teaching

I became a Fellow of the Higher Education Academy in 2014.

My teaching currently spans all years of Electrical and Electronic Engineering undergraduate and taught postgraduate programmes, as well as various pre-sessional and outreach programmes.

I lead four MSc / MEng modules; Research Project, HF-RF Engineering, Advanced CAD, Fabrication and Test, RF Design and CAD, as well as one first year module; Analogue Communications.

Other current and recent roles include:

Year 4 Tutor – MEng Integrated and Electronic Engineering (current)

Year 1 Tutor – Integrated and Electronic Engineering

MSc Tutor - Wireless and Microwave Communications Engineering (including variants – MRes & 2-year schemes)

MSc Tutor – Communications Technology & Entrepreneurship

MSc Tutor – Compound Semiconductor Electronics

I belong to the centre for high-frequency engineering (CHFE), a research group that has traditionally, and sucessfully focussed its research activities on commercial microwave communication systems, applications of compound semiconductors and more recently, resonant structures for sensing and disruption.

Compound semiconductor electronics - The CHFE is currently leading a number of groundbreaking research projects; an EPSRC funded consortium, involving numerous academic partners, developing high-efficiency, high-bandwidth envelope tracking (ET) RF modules for 5G communications systems, that require the close integration of RF and baseband electronics, using the same device technology ideally on the same GaN-on-silicon substrate. The CHFE also leads a major RF-GaN Supply chain project, GaNforCS, involving 10 industrial partners, transferring reseacrh understanding and know-how into industrial processes for volume production, enabling a UK source of RF-GaN devices for communications, security and healthcare applications.

Solid-state microwave heating and disruption - Cardiff University is a member of the radio frequency energy alliance (RFEA), a European consortium promiting the use of solid-state semiconductor technology for mass-market domestic and industrial heating and disruption applications. Current research explores the idea of multiple-feed solid state heating for microwave assisted curing of composites. There are significant benefits linked to the precise control achievable through solid-state microwave heating compared to the traditional, magnetron based and autoclave approaches.

Microwave assisted systems for healthcare - I have been involved with a number of collaborative research projects with the Schools of Dentistry and pharmacy, looking at ways in which we can use an applied microwave electrical field to a) inhibit the formation and growth of anti-microbial resistant biofilms, and b) the disruption of bacterial cell and spore to expose DNA for enhance rapid detection of antimicrobal resistant desiese. One example that is particulary important in terms of its potential impact, is the The Phoenix project is a Cardiff university gateway project in which the university is working with colleagues in Namibia to address some of the major healthcare problems which the country is currently facing. Of particular concern is the spread of antibiotic resistant tuberculosis with over 200,000 active cases at any one time. Treating the disease is particularly challenging as the current diagnostic methods lack sensitivity and speed and require access to infrastructure such as mains electricity. Given that many of the affected individuals live a nomadic life style, in areas remote from major centres of population, timely access  to healthcare is a challenge.

In joint collaboration, the schools of Engineering and Pharmacy are developing a microwave based real-time point of care assay capable of detecting a range of pathogens, including tuberculosis, within a time frame which allows the patient to be diagnosed and appropriately treated during the same healthcare visit. To develop this capability, we aim to address three linked technical challenges;

  1. The development of a simple and robust energy capture system capable of supporting the operation of the assay in areas of Namibia remote from mains power
  2. A low-power microwave disruption system capable of mediating the release of target DNA from a range of clinical samples.
  3. A simple to read, pathogen-specific lateral flow assay

The microwave disruption platform is based on solid-state microwave electronics and small single-mode resonant microwave cavities that focus a pulsed electrical field within a sample containing planktonic bacteria or bacterial spore, in order to lyse cells and liberate target DNA.

The use of solid-state microwave electronics is key to the success of this project, and importantly allows low-voltage battery and renewable energy solutions to be considered, suitble for remote field deployment.

The microwave hardware is continually being optimised, and recent research conducted at Cardiff School of Engineering has demonstrated that it is possible to reduce the size, weight and importantly the required microwave power levels dramatically, such that the power requirement for DNA extraction is now similar to that delivered by a mobile phone handset.

These advances, coupled with the high-efficiency microwave amplifier design techniques pioneered at Cardiff University, now provide the real possibility that the diagnostic tool envisaged could be powered locally using solar or simple hand-crank generators.

As part of this ongoing work, and in addition to the microwave elements, we will aim to develop a simple, mobile, electrical energy generation and storage system capable of quickly energising the diagnostic system. We will then look to deploy the combined system to Namibia and in partnership will colleagues from the school of Medicine of the University of Namibia, determine the ability of the system to detect TB in the field.

Research Contracts

Title People Sponsor Value Duration
GaNfoCS – Gallium Nitride for Communications and Security Lees J, Elgaid K, Tasker P WEFO-ERDF £2.8M 01/01/2020 - 30/08/2022
Non-linear (large signal) millimetre-wave devices, circuits and systems on-water characterisation facility PJ Tasker, R Quaglia, K Elgaid, J Bell, S Cripps, J Benedikt, J Lees EPSRC £1.5M 01/10/2018 - 01/09/2019
mm-wave power amplifiers for active antenna arrays Quaglia R, Lees J, Cripps C Huawei £73k 01/11/2018 - 01/11/2019
Development of power management and storage and efficient detection and wireless transmission for SHM systems Featherston C, Lees J, Pullin R EADS £200k 01/10/2011 - 30/09/2014
SENsors to Inform and Enable wireless NeTworks Featherston C, Pullin R, Lees J, Holford K TSB via HW Communications £143k 01/01/2014 - 31/12/2016
Montagu Featherston C, Pullin R, Lees J, Holford K TSB - Innovate UK £114k 01/05/2015 - 31/10/2017
Self-powered autonomous device for wireless structural health monitoring (SANDWICH) Featherston C, Pullin R, Lees J, Holford, K TSB £40k 01/05/2013 - 31/10/2016
RF Power Amplifiers based upon Silicon-Germanium (SiGe) BiCMOS technology (studentship) Tasker P, Lees J SiGe Semiconductor (Europe) Ltd £30k 01/10/2010 - 31/03/2014
Baseband linearisation schemes for high efficiency power amplifiers Tasker P, Lees J Infinion Technologies North America Corp £35k 01/01/2015 - 31/12/2017
High performance buffers for RF GaN electronics Tasker P, Lees J EPSRC £250k 01/10/2016 - 31/03/2020
Multi-Mode DI - ADC Belcher R, Lees J, Naylon A SELEX Galileo £100k 01/10/2011 - 31/01/2013
High-efficiency device characterisation for OperaNET Benedikt J, Lees J Freescale Semiconductor 50000 01/10/2008 - 30/09/2011
Upgrading the small equipment base for early career researchers in the Engineering and Physical Sciences Holford K, Whatling G, Lees J, Anderson P I, Brousseau E, Cipcigan L M, Pullin R, Bigot S, Theobald P, Simpson R N, Kawashita L F, Clarke A EPSRC 498326 01/11/2012 - 31/03/2013
BST Capacitor characterisation Lees J ANALOG DEVICES 3500 10/12/2012 - 09/01/2013
Efficient Composite Curing by Intelligent Microwave Processing Lees J, Evans SL, Porch A, Eaton M EPSRC Centre for Innovative Manufacturing in Composites - CIMComp, via Nottingham 49069 01/05/2015 - 31/10/2015
To develop autonomous load cells through the development of power management electronics, wireless communication and energy harvesting technologies for a wide range of monitoring applications Lees J, Pullin R, Featherston C, Eaton M KTP and Flintec 122570 01/10/2013 - 30/09/2015
Development and Realisation of Novel, Broadband, High-Efficiency Power Amplifiers (studentship) Lees J, Tasker P Freescale Semiconductor France SAS 50000 01/01/2012 - 31/12/2014
High Performance power amplifiers for phased array radar and point to point communication applications Lees J, Tasker P M/A COM Technology Solutions (UK) Ltd 45000 01/10/2011 - 30/09/2014
Integrating High-Performance Power Amplifier with Miniturized Wideband Antenna for Highly-Efficient Future Communication Devices Lees J, Tasker P, Cripps S Ser Cymru NRN AEM Swansea 59350 01/10/2014 - 30/09/2017
Development and realisation of novel broadband high efficiency power amplifiers Tasker P, Lees J Freescale Semiconductors France SAS 50000 01/10/2012 - 30/09/2015
GaN electronics: RF reliability and detradation mechanisms Tasker P, Lees J EPSRC 222392 01/01/2013 - 31/12/2015
Integration of RF Circuits with High Speed GaN Switching on Silicon Substrates Tasker P, Lees J, Benedikt J EPSRC 835074 01/04/2016 - 31/03/2019
Characterisation and comparison of packaged GaN devises Tasker PJ, Benedikt J, Lees J, Cree Inc 16931 01/05/2008 - 01/09/2008
Dynamic Characterisation and modelling of RF GaN HEMTs Tasker PJ, Lees J Ser Cymru NRN AEM Swansea 81300 01/10/2014 - 30/09/2017
Develop an ultra rapid diagnostic system capable of detecting the presence of C. difficile in a clinincal sample at the bedside in under 10 minutes Baillie L(PHRMY), Lees J, Porch A Cardiff Partnership Fund 12022 01/09/2014 - 31/08/2015
Clean and Green Microwave heating using solid state physics Cripps, S, Porch A, Lees J NXP Semiconductors Netherlands B V 30000 01/10/2011 - 30/09/2014

Supervision

Current Research Interests

I am interested in supervising PhD students in the areas of

  • High efficiency Power Amplifier Design
  • mm-wave power amplifier design
  • Microwave and mm-wave circuit design techniques
  • Medical applications of microwave engineering
  • Microwave and mm-wave characterisation

Current Students

Title Student Status Degree
Device Level Characterisation of Out-phasing Power Amplifiers Aleksander Bogusz Current PhD
Integrated Envelope Tracking Power Amplifiers for 5G communications Alexander Alt Current PhD
Measurement-Based Non-linear Modelling for Active Devices Zack Costello Current PhD
Integrating High-Performance Power Amplifiers with 

Miniaturised Wideband Antennas for Highly-Efficient Future Communications Devices

Elango Nagasundaram  Current PhD

Past projects

Supervised Students

Title Student Status Degree
A Modulated Active Load Pull Characterisation System for 5G Sattam Alsahali Graduate PhD
Investigation of Novel Measurement Techniques for Microwave Devices ALDOUMANI Anoor Graduate PhD
Solid-State Microwave heating For Biomedical Applications IMTIAZ Azeem Graduate PhD
Re-configure high efficiency power amplifiers. SHEPPHARD Daniel John Graduate PhD
Biomedical Applications of Microwave Engineering SHKAL Fatma Ahmed Graduate PhD
Novel Power Amplifier Design Using Non-Linear Microwave Charcterisation and Measurement Techniques OGBOI Friday Lawrence Graduate PhD
Baseband Linearisation Schemes for High Efficiency Power Amplifiers WANG Guefeng Graduate PhD
Use of microwave technologies in the detection of pathogenic bacteria HAMZAH Hayder Miri Hamzah Graduate PhD
Characterisation of Powders Using Microwave Cavity Perturbation CUENCA Jerome Alexander Graduate PhD
Development of an efficient energy storage and power management for autonomous aircraft structural health monitoring system THANGARAJ Karthik Graduate PhD
Power amplifier design for microwave heating applications CHAUDHRY Kauser Graduate PhD
MICROWAVE CHARACTERISATION OF AMMINES FOR ENERGY STORAGE APPLICATIONS. BARTER Michael Graduate PhD
RADIATION-BASED TECHNOLOGY TO ENHANCED MICROBICIDAL ACTIVITY OF BIOCIDES PASCOE Michael Graduate PhD
High performance power amplifiers for phased array radar and point to point communication application. KOH Minghao Graduate PhD
High Resolution Electric Field Probes With Applications In High Efficiency RF Power Amplifier Design DEHGHAN Nelo Graduate PhD
USE OF NOVEL SENSING TECHNIQUES IN NEAR NETT SHAPE MANUFACTURING. CLARK Nicholas Sebastian Graduate PhD
RF techniques applied to additive manufacturing PARKER Nyle Graduate PhD
DEVICE CHARACTERISATION FOR WIDEBAND, HIGH EFFICIENCY POWER AMPLIFIERS WILSON Richard Jason Graduate PhD
MICROWAVE PROCESSING IN ADDITIVE MANUFACTURING. HEFFORD Samuel John Graduate PhD
ELECTROMAGNETIC PROPERTIES OF SEMICONDUCTING METAL OXIDES UNDER EXTERNAL STIMULATION. PARTRIDGE Samuel Lee Graduate PhD
Sensors to Inform & Enable Wireless Networks GRIGG Stephen Graduate PhD
DOHERTY AMPLIFIER WITH AID OF AD-HOC OPTIMIZATION FOR SDR APPLICATIONS. KAMARUDIN Syalwani Binti Graduate PhD
The Auxiliary Envelope Tracking RF Power Amplifiers YUSOFF Zubaida Graduate PhD
DEVELOPMENT OF A BROADBAND AND EFFICIENT LINEAR TRANSMITTER A MOKHTI Zulhazmi Bin Graduate PhD