Conferences

3D Smith charts

The paper presents the applications of the recently proposed 3D Smith chart by means of a completely updated 3D Smith chart tool issued in September 2013. It is capable to deal with both active and passive microwave circuit parameters simultaneously. The 3D Smith chart key maps all the active and passive loads on the surface of the unit ball (inverted Riemann sphere), so that circuits with negative resistance are now assembled in the South hemisphere, circuits with positive resistance (classical 2D Smith chart) are mapped into the north hemisphere, whereas inductive and capacitive circuits are placed at the East and West of Greenwich meridian, respectively. The updated 3D Smith chart tool can plot simultaneously and in an unique manner scattering parameters, power wave reflection coefficients, voltage reflection coefficients, input and output stability circles, and deal with real and also complex characteristic impedances ports.

A Low Cost V-band Amplifier MMIC Covering 54 to 67GHz

This paper describes the design and measured performance of a low cost amplifier MMIC covering 54 to 67GHz. The IC is realised on a low cost GaAs PHEMT process produced on 6” diameter wafers with optically defined gates. The two stage design operates from a single +3V supply (44mA) with a gain of 11.5dB. The measured 1dB gain compressed output power level is +12dBm. The design includes self bias resistors to reduce performance variation with process and temperature. The paper includes details of the design approach, the simulated performance, including EM, and the RFOW measured performance.

An Engineering Approach Towards Creating Ubiquitous THz Applications

Within the wider terahertz (THz) frequency range (ca. 0.1 to 10 THz), the sub-millimetre wave frequency band (between 0.3 and 3 THz) is still considered to be a largely unexplored part of the electromagnetic spectrum. This ‘THz Gap’, between conventional electronics and photonics, offers the real potential for both scientific and commercial exploitation. However, while the majority of THz groups focus on the former, it is the latter that offers the key to bridge the THz Gap to ubiquitous applications. To this end, new engineering solutions are needed in modelling (mathematical & numerical), design (synthesis & analysis) and fabrications (precision & volume production). As ubiquitous THz applications emerge, the costs of associated passive components, active devices and metrology will fall, creating a positive spiral of growth in all areas; enhancing our modern day living and with the prospect of a huge societal and economic impact.

This lecture will examine the various facets associated with adopting an engineering approach towards creating ubiquitous THz applications. More specifically, for the many engineers currently working at microwave and millimetre-wave frequencies (below ca. 100GHz), the challenges for working with shorter wavelengths and with more complicated carrier transport and molecular physics will be explained. The lecture will also give, by example, a unique perspective on THz engineering – with conventional approaches and new paradigm shifts – from nano structures, metamaterials and solid-state & vacuum electronics to complete systems level integration, ubiquitous applications and their impact.

Clipping Contours: An RFPA Design Tool

This paper presents the "clipping contour", a new RFPA design tool which enables the designer to visualise and control the possibly detrimental effects of the second harmonic impedance, maintaining power, linearity and efficiency in broadband RFPA designs. This new tool allows the designer to prevent the voltage waveform from crossing zero, thus clipping the current waveform and degrading performance. This simplifies the process of managing waveform interaction with the device knee region, and expands the continuous mode design space to incorporate non-zero second harmonic resistive matching. A design example is fabricated, demonstrating the utility of the second harmonic clipping contour tool as part of the PA design process. A 10W GaN demonstrator gives measured CW power >8.5W, drain efficiency >60%, and better than -30dB ACPR over a bandwidth of 1-2.9GHz.

GaN, an Enabling Technology for Enhanced Radar Performance

GaN is now well established as a mainstream semiconductor material that provides many electrical and physical advantages over the traditional Si or GaAs technologies. In this paper we review some of the latest developments in this area and how the capabilities of this new material are enhancing the performance of new radar systems. 

PCB Breakouts for Small Form-Factor RF Circuits

This paper describes the application of a PCB manufacturing technique to produce very small RF circuits, which are easily testable deployable and programmable. Design rules for successful replication of the technique are given. The RF performance of an example PCB manufactured using this technique is quantified.

Renewable Energy Ad-hoc Communication Hub (REACH)

Many people in developing countries cannot enjoy the benefit brought by mobile communication, such as education, e-health, medical treatment and disaster warning etc.  Because of the poor power supply network infrastructure, mobile coverage in developing countries cannot keep up with the fast growth of mobile phone users, for example in Africa, the average network coverage is only 15%.  It is predicted that mobile coverage there will only expand slowly, as the conventional electricity-hungry mobile base stations need the power grid to operate.  This will increase the emissions of carbon dioxide and other toxic pollutant.  REARCH is an immediate and clean solution to address this problem.  With its green power source and embedded antenna system design, it can be efficiently deployed to form its co-operative ad-hoc mobile networks for expanding the coverage in areas far away from the national power grids. Therefore people living in remote or off-power-grid areas could access mobile network connections for the first time.

The key technology of REARCH is the novel embedded high performance antenna systems that can amplify and relay the mobile phone signal to the users in the remote areas.  There are reception blind spots, power/range problems in the existing base station scenario in developing countries; we cannot simply increase the output power to cover the blind spots and extend the range.  An alternative smart way to solve the problem is to use a combination of high-gain, may be beamforming, antenna and high-efficiency signal repeater to collect radio waves from the nearby mobile phone base stations. Then the amplified signal can either transmit to other stations for even longer range communication through the ad-hoc network technology, or create a signal shower through the omni-directional antenna serving the people around the stations. REARCH’s embedded design enables easy deployment of the station in different geographical environments.

In addition, the renewable energy source, for example flexible solar panels mounted on the foldable top of the stations, will generate electricity without connecting to any power plants.  The generated electricity will power the antenna system and charge up the high-capacity reserve batteries.  It also has a recharge socket for mobile phones or other mobile devices.  This innovation will significantly reduce the discharge of carbon dioxide and other toxic pollutant.  Moreover REARCH will work particularly well initially in African and Middle Eastern countries, because many people there live in small remote and separated villages located around different part of the countries. It is not cost effective to setup a dedicated mobile base station and the required power grid to serve a small community.

The three functional prototypes have proven to be a success, and we will utilise the know-how gained for the large-scale deployment of the concept and technology.