RF Design, Development and Test

• Hands-on fault finding and debugging of multi-layer FR4 and Rogers® PCBs, surface mount to 0402.
• VCOs (negative resistance Colpitts types): development, improving performance across temperature.
• Basic oscillator circuits designed around both bipolar transistors and JFETs: Colpitts, Clapp and Hartley architectures.
• S-parameter measurements: design and conversion to/from T-parameters, including: gain, return loss, VSWR, isolation, Rollet stability factor, matching and de-embedding cable effects.
• Smith chart measurements: (Z, Y and YZ), analyses, interpretation and matching, distributed and lumped elements.
• Vector network analyzer Q-factor and tan delta measurements: reactive component selection.
• Low noise amplifiers: bipolar and FET: GaAs MESFET, HEMT and PHEMT (NF circles and optimum source noise match).
• Power amplifiers (few 10s of watts, class A linear, B and AB push-pull) at HF and VHF.
• PIN diode attenuators, absorptive (bridged-T, pi, single and dual device packages) and reflective (λ/4 spaced).
• Frequency hopping synthesizer (E-GSM): reduced parts count, improved grounding, rationalised PCB layers, reduced cost and improved performance.
• PIN diode switches (high isolation) and phase shifters: performed detailed evaluation.
• Microstrip, CPS, CPW and stripline/triplate controlled impedance lines (FR4 and Rogers® substrates): simulated (ADS®) and built.
• Wideband transformers/baluns: developed twisted wire and transmission line types on high frequency (NiZn) ferrite formers.
• Space equipment hardware: development, evaluation, results analyses and processing (multi-port S-parameters).
• Satellite ground station equipment, design and development: intermediate data rate (QPSK) over C-band and Ku-band.
• GPS receiver development (ECCM application), including bandpass sampling (undersampling).
• Power combining/splitting: developed Wilkinson, branch line, Lange and rat race / ring architectures on FR4 microstrip.
• IP3, P1dB, SFDR measurements, their interpretation and calculations (Excel®, ADS® and MATLAB® RF Toolbox®).
• High speed ADC specification: Analog Devices®, for bandpass and baseband sampling.
• Dual modulus synthesizers: development, loop filter calculations, programming (Texas Instruments® LM2306).
• Fractional N synthesizers: new (reduced size) die evaluation (GSM 900 MHz basestations).
• Dual loop synthesizers: upgrade from switched crystal oscillators (reduced power, weight, space; airborne application, VHF/UHF).
• Legacy (navigational) receiver upgrade: improved and rationalised RF layout, reduced parts count (upgraded a module supplied 20 years earlier).
• Passive (LC) sampling bandpass filter design from scratch at HF/VHF using filter tables (Williams - Taylor).
• Characterisation of 'soft' ferrite materials for VHF (Siemens/EPCOS®), Fair-rite: various geometries).
• Designed directional couplers for VSWR monitoring at VHF and UHF (portable transceiver application).
• Design of high isolation double balanced mixers: ferrite torroids, VHF LO (large HF OTH radar system).
• Design of a high Q absorptive notch filter (near-to-carrier transmitter spurious measurements at HF).
• Developed a Schottky diode envelope detector circuit and high slew-rate video stages for a radar receiver.
• Designed a constant delay slope video low pass filter (for high percentage bandwidth IF detection).
• Evaluated successive detection logarithmic video amplifiers (SDLVAs) and specified improved versions at half the original cost.
• 2.4 GHz ISM band wireless networks: developed IEEE 802.15.4 control and monitoring solutions.
• Performed pre-compliance DO-160 (19/20/21) design and test (LED lighting product).
• Analyses on-air PHY and MAC level wireless packets using Wireshark 2.2.0® (IEEE 802.15.4).
• Developed an active load for CCD readout electronics (space hardware).

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Microwave and Millimetre Wave Design and Development

• Alumina and Rogers® based microstrip development of GaAs FET LNAs (K/Ku-band space equipment).
• SSPA and TWTA specifications: their interpretation (power handling and efficiency, space platform system).
• Space hardware receivers: evaluation and development (TV broadcast satellite).
• Lange couplers, branchline couplers (design and evaluation), Ku-band mixers.
• Designed Cassegrain and front-fed parabolic reflector antennas and evaluated them (far field Q-band).
• Designed a range of dual mode (smooth conical) Potter horn antennas (for Q-band two dimensional Gaussian illumination).
• Designed and developed various passive millimetre wave waveguide structures using electro-formation techniques.
• Beam waveguides: via refractive (polyethylene lenses) and ellipsoid reflective transmission.
• Designed quasi-optic (Gaussian and Gaussian-Laguerre) antenna feed structures for transmission of 2D and 3D monopulse tracking.
• Developed a precision VNA phase/amplitude interface (lens antenna measurements using the HP 8510® network analyzer).
• Developed a set of absorptive antenna isolators for an ECM product that improved the receiver threshold by a at least 20 dB across X-band and K-band.

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Non-RF

• Implemented a AES-CCM-128 (NIST) encryption algorithm for a demonstrator using MATLAB 2016b®.
• DC-DC converters (SMPS): specification, heat dissipation and mechanical (seaborne product, unusual voltages).
• ADC interfacing: anti-alias filtering, offset/gain setting (spectrum analyzer interface).
• Linear low power regulators: general specification and use.
• Design of audio amplifiers, buffer circuits and general purpose operational amplifier circuits.
• DC power reduction techniques for battery operation, component selection for variety reduction (low-cost portable transceiver application).
• Interfacing to PC architecture: (GPIB/IEEE-488, RS232/422/485), PIO cards (National Instruments® and Bluechip Technology®).
• Microchip Technology® PIC 24F and 32MX (16/32 bit) micro-controllers and DSP ICs: MPLAB XIDE IDE® programming/debug.

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System Level Hardware

• Improved terrestrial broadcast quality of service figures for MF and VHF radio, UHF TV and DAB.
• RF over optical fibre (indirect modulation) system development and implementation (DWDM, λ = 1550 nm, submarine optical).
• RF over optical fibre (direct modulation) debugging and evaluation (full duplex, λ = 1550 nm and 1310 nm): coverage extension solutions for digital cellular 2G, 3G and 4G/LTE services.
• Specification and evaluation of fibre optic components: EDFAs, Mach Zehnder optical intensity modulators, circulators, WDM filters (add-drop multiplexers), laser diode sources and control ICs (RF over optical fibre demonstrator).
• Proposed high level satellite payload DSP architectures to replace analogue ones (design study, presentation).
• Investigated multiple port amplifiers, as an alternative to switched redundancy on satellite payloads (design study and presentation).
• Proposed high level active transmit and receive antenna arrays to replace passive antennas (X/Ku bands study and presentation).
• HF over-the-horizon radar systems: receiver and LO distribution, provided design support and implementation.
• Provided engineering support for communication equipment proposals: transportable digital tropospheric scatter equipment, microwave LOS links, HF broadcast stations, satellite receivers and IF group delay equalisers.
• Propagation studies and performance predictions for HF channels, VHF (Bullington), tropospheric scatter and microwave LOS/diffraction links.
• Frequency planning to manage intermodulation distortion and wide range harmonic products.
• Interfacing to SDH/SONET data rates: ECL, CML, LVDS on FEC modules with Reed Solomon 15/14 coding (submarine optical fiber terminals).
• Specified a high stability, high reliability local oscillator distribution system (HF OTH calibration receiver).
• Developed program suite for digital LOS link performance predictions.
• Authored deliverable worst case analysis (WCA) reports and failure mode, effects and criticality analyses (FMECA).
• Systems analysis support for performance improvement of an electronics intelligence (ELINT) radar receiver (to zero-IF complex baseband).
• Developed Rayleigh and Rician multipath fading models using Matlab®.
• Co-site interference cancellation techniques.

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ADCs, DSP, other Hardware and Software

• Developed analog signal conditioning operational amplifier circuits to interface Burr Brown ADS7805 16 bit ADC® (100 ksps).
• Specified wideband balun ADC interfacing for bandpass sampling (undersampling) ADC (Minicircuits®, Analog Devices®).
• Developed Excel® tools to convert between jitter and phase noise (VCO).
• ADC parameters (investigation, Analog Devices®): resolution, quantisation noise, sampling, phase noise, dithering, integrated non-linearity, differential non-linearity, coding, multiple carry, windowing, spectral leakage, coding, FFT.

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CAD Packages, Applications and Programming Languages

• Microsoft Office Professional 2019: Word, Excel, Access, PowerPoint
• Microsoft Windows 10 Professional 64-bit
• Mathcad 15
• Visual Basic 2015 Express
• Agilent Advanced Design System (ADS) 2009
• Microwave Office 2012
• Ansoft Designer 2.2.0
• Visio Professional 2019
• Mentor Graphics (Unix)
• Eagleware/Genesys 2005
• ANSI-C (David Himmel)
• Visual C++ 2015 Express
• Visual Basic 2015 Express
• Altium 2012 Viewer
• Simetrix 7.10
• MathCad 15
• MATLAB 2020b
• MATLAB Toolboxes and Applications:
• Antenna Toolbox Version 4.3
• Communications Toolbox Version 7.4
• Simulink Version 10.2
• Control System Toolbox Version 10.9
• DSP System Toolbox Version 9.11
• Data Acquisition Toolbox Version 4.2
• Instrument Control Toolbox Version 4.3
• Parallel Computing Toolbox Version 7.3
• Phased Array System Toolbox Version 4.4
• RF Blockset Version 8.0
• RF Toolbox Version 4.0
• Signal Processing Toolbox Version 8.5
• Simscape Version 5.0
• Simscape Electrical Version 7.4
• Simulink Control Design Version 5.6
• Spreadsheet Link Version 3.4.4
• Symbolic Math Toolbox Version 8.6

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