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Armms RF and Microwave Society
Book for the Apr 2023 conference »


Monday 7th November to Tuesday 8th November 2022 at Wyboston Lakes, Wyboston

Bookings for the November 2022 conference are now closed

The meeting commences at 12:30pm on the Monday, starting with lunch.


Young Engineer Sponsorship: The ARMMS RF & Microwave Society provides sponsorship for young engineers (28 or below) who have had papers accepted for presentation at each meeting. Sponsorship is £200 cash plus free attendance (including conference dinner and overnight accommodation). Potential candidates should identify themselves as eligible at time of submission and state their date of birth. This offer is limited to a maximum of 2 places per meeting.

Best Paper Award: The Steve Evans-Pughe prize is awarded to the best presenter at each meeting and is sponsored by NI.. The award is a gift of the winners choosing to a value of £200 for the best paper and £50 for the runner-up. 

For exhibition enquiries please email, for all other enquiries please email


Wyboston Lakes
Great North Road
MK44 3AL



John Walker

Tel+44 753 569 0333


A Hybrid Approach to Manufacturing Waveguide Components Utilizing 3D Printed Wax Impressions and Non-ferrous Metal Casting

John McGreevy, Ben Shaw & Martin Foxton

An alternative approach to manufacturing waveguide components and assemblies using 3d printing a wax impression and then investment casting is presented.

Waveguide components are conventionally fabricated using drawn tube, machined components, and castings. These are assembled using brazing, adhesives, or screws. Recently interest has grown in additive manufacturing of waveguide components, particularly 3d metal printing. An alternative hybrid approach is to 3d print a wax impression which can then be investment cast to produce a metal component. This has several advantages over metal printed components, namely lower surface roughness, wider range of non-ferrous metal alloys (including aerospace grade aluminum, brazeable aluminum and copper alloys), lower printer costs. The possibility of using this technique for manufacturing waveguide components and assemblies has been investigated.

Comparative results are presented for a machined and brazed waveguide bend assembly, a 3d metal printed waveguide bend assembly and a 3d printed wax and investment cast waveguide bend assembly. Additional results are presented for a magic tee, waveguide mixer and monopulse comparator manufactured by 3d printing a wax impression and then investment cast.

A Polynomial Based Model of Input and Feedback Capacitors Suitable for Volterra Analysis of RF Amplifiers

Nagaditya Poluri, Alex Moores, Robin Sloan, Maria Merlyne De Souza
University of Sheffield and Microwave inspection Tech. Ltd

Highly efficient and linear amplifier are required to meet the stringent requirement of fifth generation mobile networks. Volterra analysis has been shown to aid selection of impedances and bias point for linearity in this context.   In Volterra analysis, non-linearities are typically modelled using a polynomial to decompose the overall distortion at the output of an amplifier into second, third, and higher order effects and to quantify the contributions from capacitances and from those of the current generator. The distortion due to the non-linearity of the input and feedback capacitance is often significant and comparable to the distortion due to the non-linear current generator. In this work, we explore a polynomial-based model of Cgs and Cgd derived by enforcing charge conservation at the gate terminal. The proposed approach resolves the problem of divergence of the polynomial beyond the range of values for which the fitting is performed. Additionally, since the charge conservation at the gate terminal is imposed, overfitting of the polynomial to noise in the measured data that results in un-realistic derivatives is avoided. The accuracy of the proposed model is demonstrated for Ka-band devices.

An X-band Pulse Compression Instrumentation Radar for RCS Characterisation

Alex Scarboro

The design, development and realisation of a system for Radar Cross Section (RCS) characterisation of an Uncrewed Surface Effect Vehicle (USEV). Consisting of an X-band Qorvo 4W PA/LNA, a near full-band up/down block converter and a wideband software-defined pulse processor, the system can also be used as a platform for the development of complex radar waveforms. An integrated electro-optics package provides wireless laser range finding and low latency video for visual object recognition and tracking of cooperative and non-cooperative targets.

Design and Manufacture of Multi-channel Microwave Rotary Joints

Saeed Zakerizadeh
Link Microtek

Radar and surveillance systems over the last several decades have undergone major changes with much focused on transmitter design,  receiver design, antenna modelling and signal processing.

Little though is mentioned about the rotary joints and how these complex assemblies are engineered. As an interfacing medium that permits RF continuity at power or high frequency while allowing controlled motion, the design and manufacturing considerations have direct impact on overall system performance. As the only UK designer and manufacturer of such devices, we aim to highlight some of the development challenges, their system impact and approaches that can be taken to address them.


GaN transistors for RF Energy

Dr. Stephan Holtrup

RF power transistors and MMICs are mainly applied and well proven in radar and telecommunications systems.  However, RF power can also be used for other purposes, such as e.g. accelerating particles or generating heat, with the sole intention of delivering nothing but energy.  Hence the “RF energy” application classification.

RF GaN processes and packaging technology are constantly improving, resulting in actual mature technologies and devices capable of very well addressing this RF energy market, which covers a wide range of applications such as scientific and medical particle accelerators, medical treatments, industrial heating, commercial cooking, plasma generation, chemical processing, etc.

The presentation will highlight the benefits of transitioning to solid-state GaN-on-SiC devices from the incumbent vacuum tubes to generate RF energy.  A corner of the veil will be lifted on the latest Wolfspeed technologies including a new GaN-on-SiC device targeting professional microwave cooking applications.  Some typical existing applications will highlight the potential of solid-state RF energy generation and open a vision on prospects and projections for further adoption.

High-Speed Electro-Thermal Measurements in RF Power Amplifiers Using Thermo-Reflectance

Gautam Jindal; James W. Pomeroy; Gavin T. Watkins; Kevin Morris; Martin Kuball; Tommaso Cappello
University of Bristol

The methodology presented here provides a route for directly performing high-speed electro-thermal characterisation on a Power Amplifier (PA) using Thermo Reflectance method. Starting the analysis with RF pulses, the PA electrical and thermal behaviour at different ambient/baseplate temperatures and dissipation profiles is measured with the presented setup. After this, the on-chip intra-finger temperature of this PA, based on a GaN-on-SiC Wolfspeed CG2H40010F transistor, is measured by considering high-PAPR signals with bandwidths of 10 kHz, 100 kHz, and 10 MHz. For the 10 MHz modulated signal, no in-signal temperature fluctuations are observed during the amplification, whereas for 10 kHz a maximum variation of ± 7 °C and ± 3 °C for a 100 kHz signal is measured.

How to Package mmWave MMICs

Liam Devlin
PRFI Limited

The mmWave frequency bands are increasingly becoming commercialised for high-volume applications, including automotive radar, 5G, fixed wireless access (FWA) and LEO satellites. This demand has driven the need to package low-cost mmWave components in surface-mount plastic packages that are suitable for high-volume assembly, while retaining high yields and reducing manufacturing costs.

Although mmWave SMT packages resemble those used at lower frequencies, packaging parasitics become much more important at higher frequencies and their potential to cause serious performance degradation is greatly increased.

This presentation is aimed at helping engineers understand the issues and avoid the problems. It also provides an overview of how to optimise the performance of mmWave packaged ICs using a range of SMT packaging technologies, based on the author’s practical experience. It will explore the problems that can be caused by packaging parasitics, and will describe proven techniques for implementing high performance packaged mmWave ICs. Different packaging technologies will be considered, and their relative pros and cons will be reviewed.

Modular Design and Characterization of a Reconfigurable Sequential Power Amplifier

Sarmad Ozan, Manish Nair, Mark A. Beach and Tommaso Cappello
University of Bristol
This paper demonstrates a modular design approach for a sequential power amplifier (SPA) with reconfigurable output power back-off (OPBO) characteristics. The proposed dual-input SPA consists of a main amplifier (10 W), a peaking amplifier (25 W), and a 6.5 dB coupler. This SPA is implemented by using two off-the-shelf PAs both with overlapping bandwidths between 3.3 and 3.7 GHz. When combined together the SPA presents the same operational bandwidth but with additional enhanced backoff efficiency. This SPA achieves a peak drain efficiency of 51% at 9 dB back-off, and 36% at maximum output power at 3.5 GHz while maintaining the same bandwidth of the two constituent
PAs. The resulting SPA performance is competitive with other state-of-art Doherty PAs and SPAs.

Moving up in frequency - D-band the next frontier for the telecommunications XHaul

Tudor Williams

This paper explores how D-Band (130-175GHz) enables the potential for next generation, ultra-high-capacity wireless links for 6G and beyond. Moving to D-Band is a fundamental shift and will require radical redesign due to the very high frequencies. This presentation will explore why a shift to higher mmWave frequencies is required and outline the challenges associated with manufacturing transceivers in volume at D-Band, including the availability of power semiconductor processes, device interconnects and packaging. 

On-wafer Measurement of Millimetre-wave Circuits: from Calibration to Verification

James Skinner, Sang-Hee Shin, Daniel Stokes, and Xiaobang Shang

Reliable S-parameter measurements of on-wafer devices play an important role in the development of integrated planar circuits for applications exploiting the millimetre-wave spectrum. However, as you move into this frequency range additional complexities are introduced as compared with measurements at RF and microwave frequencies. Factors such as the choice of calibration method, coupling between adjacent neighbouring structures on the same wafer, crosstalk between probes and the design of calibration standards, to name just a few, all significantly affect measurement results at millimetre-wave frequencies and above. This paper will give insight into the impact of these factors, giving case studies as evidence. Additionally, some ‘good practice’ for on-wafer measurement will be provided, giving guidance on areas such as achieving good consistency in results between different operators, and how to ensure confidence in measurement results. NPL actively supports industry and academia through on-wafer S-parameter measurement and provides test facilities and consultancy in support of a variety of applications. This paper will also briefly describe the current on-wafer capability at NPL and the latest research activities related to this technique.

Optimum N-way Power Divider Using Klopfenstein's Taper

Steve Huettner, Tim Cruz
Cubic Nuvotronics

A proposed eight-way corporate power divider uses Klopfenstein’s taper equations to provide optimum equalripple input match from a chosen lower frequency with the shortest possible length. The divider is realized in PolyStrata® coax, operates from 2 GHz to 42 GHz, with 1.5 dB maximum loss in a 1-inch diameter radial divider SMT footprint and is capable of ten-watt CW input. The described technique can be used in all N-way wired divider or combiner designs.

Reinventing the Balanced Amplifier

Steve C Cripps
University of Cardiff

The quadrature balanced amplifier is a truly iconic configuration and was at one time the default approach to achieving broad, multi-octave band performance from active devices that could not be matched over such bandwidths. It has fallen out of favour in the recent couple of decades, mainly through a renewed industry focus on much narrower communications bands, but also the availability of matched broadband MMICs which use the distributed approach.  Recently however, this interest has burgeoned due to two important properties of the balanced amplifier that were largely unobserved, and certainly ignored, in its earlier heyday. Firstly, the ability to tune the output loads seen by both transistors actively, using an injected signal at the isolated output coupler port, known as the “Load Modulated Amplifier”, or LMBA, has seen important applications in maintaining efficiency under power backoff conditions, thus providing a broader band solution than classical configurations such as the Doherty PA.   Secondly, this has opened up possibilities for mitigating variations in the output termination match which is a very pertinent issue in 5G phased array systems. These techniques, and applications will be discussed in this presentation.

Revisiting Rectennas For Low-Power RF Power Transmission: Non-Linear Antenna-Circuit Co-Design and Multi-Diversity Antennas

Mahmoud Wagih
University of Glasgow

Despite being conceived over 60 years ago, rectennas have had limited adoption in commercial applications. In this presentation, multiple approaches for designing high-efficiency and high-sensitivity rectennas for low-power internet of things applications is presented. First, impedance matching and tuning methods used to overcome the key device challenges including diode losses and accurate modelling will be summarized. The ability to rectify µW inputs at sub-1 GHz frequencies with an RF-to-DC efficiency in excess of 40% at −20 dBm using commercial Schottky diodes will be demonstrated. The challenge of transitioning low-cost rectennas realized on low-cost flexible substrates (e.g. organic polymers and textiles) using hybrid RFIC packaging will be presented. Using a GaAs diode bonded onto a textile-based antenna, the first rectenna capable of harvesting mmWave power in the 5G 26/28 GHz bands will be presented. Hybrid antennas and rectennas for simultaneous wireless information and power transfer (SWIPT) will also be presented, showing examples of battery-less low-power systems powered using RF energy harvesting.

W Band High Range Resolution Altimeter Developments in Arralis

Ali Dagdeviren

The range resolution capability of the aircraft altimeter is one of the key parameters during the precise height measurements. During the landing of the rotary-wing aircraft, it is vital to detect the obstacles such as power cables, especially in poor visibility conditions like snow (White-out) and dust clouds (Brown-out) to assist a safe landing.

For lower height measurements, Frequency Modulated Continuous Wave (FMCW) radars are used to achieve a better resolution with the aid of higher bandwidth. However, this comes with two challenges: (1) the design complexity of the Radio Frequency Integrated Circuit (RFIC) (2) the high rate of atmospheric attenuation caused by the gases and aerosols.

Using the frequencies in the neighbourhood of 94 GHz for the transmission significantly reduces the atmospheric attenuation and provides an atmospheric transparency window.

In this paper, the W Band FMCW altimeter radar developed by ARRALIS is described. ARRALIS comes with the solution of both integrated circuits and modules used in a transmitter/receiver chain designed for the W Band. This provides a complete FMCW radar system working in the frequency range of 92-96 GHz with the aid of commercial off the shelf analog to digital converters and Digital Signal Processing (DSP) evaluation boards. Thus, by achieving a 4 GHz bandwidth at the centre of 94 GHz, a theoretical range resolution of 3.75 cm is achieved, which is then degraded by the windowing function factor during converting the signal into the frequency domain. The FMCW radar system uses a triangular waveform by default, which then can be converted to other waveforms as well

Why migrate from LDMOS to GaN?

Kevin Browne
Richardson RFPD

RF Silicon LDMOS rose to prominence during the early 1990s, due to its greater capability over Silicon Bipolar transistors by delivering better linearity, gain & efficiency at a lower cost.  It became the dominant technology for RF applications.  RF LDMOS was the default for many RF amplifiers, plus industrial & medical applications.

In our changing world there are again evolving demands for higher frequency, higher efficiency, higher bandwidth & power.  Other technologies can address higher frequency i.e. Gallium Arsenide (GaAs), Silicon Germanium (SiGe), Gallium Nitride (GaN) & other esoteric materials. GaAs is long established for high frequency devices all the way to 100GHz, but typically it is low voltage, limiting the power it can deliver.

GaN is an enabling technology for many emerging RF applications, since it can address many of the combined requirements simultaneously; high frequency with wide bandwidth & high power and excellent efficiency by using power amplifier (PA) architectures that play to the strengths of GaN, such as Doherty, Envelope Tracking and Digital Pre-Distortion. GaN enables higher band 5G PAs in the sub-6GHz market, its high Ft enables multi-watt PAs for 5G millimetre wave applications.  GaN enables high power solid-state Sat Coms PAs and control products in the Ku, Ka & Q or V bands.

GaN is not ‘better’ than LDMOS per se, but it is sometimes the only technology that fits. It has been adopted in Aerospace & Defense applications for some time, but the wider adoption of GaN increases volumes & enables lower cost. GaN is now mainstream & that is because of cost & the wide array of devices; discrete transistors & MMICs currently available. It is possible to easily find a GaN part that meets your application needs. This paper will look at GaN’s advantages & some practical limitations.


The society would like to thank Melcom and Wolfspeed for sponsoring the November 2022 meeting:


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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