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Dr Jonathan Lees

Dr Jonathan Lees

Lecturer - Teaching and Research

School of Engineering

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

I began my career in 1998 developing optical and GPS-based positional tracking solutions with QinetiQ, U.K.  I became a chartered Engineer in 1999 and obtained my MSc. and PhD. degrees from Cardiff University in 2002 and 2006 respectively. I am currently employed as a Senior Lecturer in Non-Linear Microwave Characterisation within Cardiff University’s Centre for High Frequency Engineering (CHFE) where 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. My work in this area includes 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 recent research activities include investigation into RF properties of materials, microwave heating and disruption and application of microwave engineering to healthcare diagnostics.

I joined Cardiff University as a Research Associate in June 2005, became a Lecturer in 2011 and Senior Lecturer in 2016. From 2009 to 2010, I was seconded to Mesuro as a Senior Hardware Engineer. I received his PhD in 2006 from Cardiff University.

My academic roles have included Director of Taught Postgraduate programmes, Year-1 Tutor for Integrated and Electrical and Electronic Engineering and Director for the MSc in Wireless and Microwave Communications Engineering. My current 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. I am currently a Lecturer in Non-Linear Microwave Engineering, and 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

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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 modules: HF-RF Engineering, MSc Research Study,  Software Tools and Simulation, Advanced CAD, Fabrication and Test, as well as one first year module: Electronics Laboratory. I also teach on three other modules: Electrical and Electronic Engineering 4, Analogue Electronics and RF Cad and Design.

Other current and recent roles include:

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 in commercial microwave communication systems and more recently, applications of resonant sensors and applicators for sensing and disruption. The research opportunities that I am now focussing on exist in the key areas of compound semiconductor electronics, solid-state microwave heating and microwave assisted systems for healthcare.

Solid-state microwave heating and disruption– Cardiff University is a member of the radio frequency energy alliance (RFEA), a new European consortium promiting the use of solid-state semiconductor technology for mass-market domestic and industrial heating and disruption applications.  I currently supervise a self-funded PhD student looking into multiple-feed microave heating structures, which is highly aligned with this space. A number of patent disclosures have recently been initiated and the flexibility provided by this research leave would allow me to accelerate this work. 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 am currently 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.

 

Compound semiconductor electronics- The CHFE is currently leading an EPSRC funded consortium, involving numerous academic partners, developing high-efficiency, high-bandwidth envelope tracking (ET) RF modules for 5G communications systems. These modules rely on the close integration of RF and baseband electronics, using the same device technology ideally on the same GaN-on-silicon substrate. To achieve impact in this area, this work needs to be accelerated.

In addition, there are a number of novel RF-to-DC rectifier circuit ideas that are emerging from Cardiff activities in the baseband modulator space that, fall outside of the defined project scope. These potentially offer significant advantage over conventional techniques, and I believe that this area needs to be urgently investigated to exploite publication and possible research grant opportunity.

Research Contracts

Title People Sponsor Value Duration
Development of power management and storage and efficient detection and wireless transmission for SHM systems Featherston C, Lees J, Pullin R EADS 19980 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 143963 01/01/2014 - 31/12/2016
Montagu Featherston C, Pullin R, Lees J, Holford K TSB - Innovate UK 114378 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 39816 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 30000 01/10/2010 - 31/03/2014
Baseband linearisation schemes for high efficiency power amplifiers Tasker P, Lees J Infinion Technologies North America Corp 35000 01/01/2015 - 31/12/2017
High performance buffers for RF GaN electronics Tasker P, Lees J EPSRC 249999 01/10/2016 - 31/03/2020
Multi-Mode DI - ADC Belcher R, Lees J, Naylon A SELEX Galileo 100000 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

Supervised Students

Title Student Status Degree
Device level characterisation of out-phasing amplifiers BOGUSZ Aleksander Current PhD
Investigation of Novel Measurement Techniques for Microwave Devices ALDOUMANI Anoor Current PhD
Solid-State Microwave heating For Biomedical Applications IMTIAZ Azeem Graduate PhD
Re-configure high efficiency power amplifiers. SHEPPHARD Daniel John Current PhD
INTEGRATING HIGH-PERFORMANCE POWER AMPLIFIERS WITH MINIATURIZED WIDEBAND ANTENNAS FOR HIGHLY-EFFICIENT FUTURE COMMUNICATION DEVICES. NAGASUNDARAM Elango Current PhD
Biomedical Applications of Microwave Engineering SHKAL Fatma Ahmed Current PhD
NOVEL POWER AMPLIFIER DESIGN USING NON-LINEAR MICROWAVER CHARACTERISATION AND MEASUREMENT TECHNIQUES OGBOI Friday Lawrence Graduate PhD
BASEBAND LINEARISATION SCHEMES FOR HIGH EFFICIENCY POWER AMPLIFIERS. WANG Guefeng Current PhD
Use of microwave technologies in the detection of pathogenic bacteria HAMZAH Hayder Miri Hamzah Current PhD
Characterisation of Powerders 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 Thesis Submitted PhD
Power amplifier design for microwave heating applications CHAUDHRY Kauser Current PhD
MICROWAVE CHARACTERISATION OF AMMINES FOR ENERGY STORAGE APPLICATIONS. BARTER Michael Current PhD
RADIATION-BASED TECHNOLOGY TO ENHANCED MICROBICIDAL ACTIVITY OF BIOCIDES PASCOE Michael Current PhD
High performance power amplifiers for phased array radar and point to point communication application. KOH Minghao Thesis Submitted 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 Current PhD
RF techniques applied to additive manufacturing PARKER Nyle Current PhD
DEVICE CHARACTERISATION FOR WIDEBAND, HIGH EFFICIENCY POWER AMPLIFIERS WILSON Richard Jason Current PhD
MICROWAVE PROCESSING IN ADDITIVE MANUFACTURING. HEFFORD Samuel John Current PhD
ELECTROMAGNETIC PROPERTIES OF SEMICONDUCTING METAL OXIDES UNDER EXTERNAL STIMULATION. PARTRIDGE Samuel Lee Current PhD
Sensors to Inform & Enable Wireless Networks GRIGG Stephen Current PhD
DOHERTY AMPLIFIER WITH AID OF AD-HOC OPTIMIZATION FOR SDR APPLICATIONS. KAMARUDIN Syalwani Binti Current PhD
The Auxiliary Envelope Tracking RF Power Amplifiers YUSOFF Zubaida Graduate PhD
DEVELOPMENT OF A BROADBAND AND EFFICIENT LINEAR TRANSMITTER A MOKHTI Zulhazmi Bin Current PhD