Novel Sub-Harmonic Injection-Locked Balanced Oscillator

A novel sub-harmonic injection-locked balanced oscillator is proposed. The circuit provides two outputs with a 180° ° phase difference by employing a transmission line section for impedance transformation to meet the oscillation conditions. A coupling network is connected at the mid-point of the transmission line to inject the sub-harmonic frequency. This eliminates the need for a circulator or balun. The circuit is small and consumes low DC power. Under the locking state, the circuit provides double the injection frequency and also the phase noise of the two outputs is substantially improved

Analysis and design of a differential sampled-line six-port reflectometer

The analysis and design of a differential six-port reflectometer (SPR) based on a sampled-line structure is presented in this paper. The practical differential SPR is realized in Coplanar Strip (CPS) transmission line form, using two baluns for interfacing with the RF source and device under test (DUT) and four baluns connected to the RF logarithmic detectors. The performance of the proposed differential SPR structure is evaluated with a common-mode rejection ratio analysis and impedance measurement. A prototype differential SPR was designed and fabricated at 1 GHz in order to verify the analysis. Measurement results for various load impedances are compared with the measured results obtained from a commercial automatic vector network analyzer. It is shown that the differential structure gives a significant advantage in rejecting common-mode interference signals

Linearisation techniques for microwave direct-carrier transmitters

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Microwave and Millimetre-Wave Design for Wireless Communications

This book describes a full range of contemporary techniques for the design of transmitters and receivers for communications systems operating in the range from 1 through to 300 GHz. In this frequency range there is a wide range of technologies that need to be employed, with silicon ICs at the core but, compared with other electronics systems, a much greater use of more specialist devices and components for high performance – for example, high Q-factor/low loss and good power efficiency. Many text books do, of course, cover these topics but what makes this book timely is the rapid adoption of millimetre-waves (frequencies from 30 to 300 GHz) for a wide range of consumer applications such as wireless high definition TV, “5G” Gigabit mobile internet systems and automotive radars. It has taken many years to develop low-cost technologies for suitable transmitters and receivers, so previously these frequencies have been employed only in expensive military and space applications. The book will cover these modern technologies, with the follow topics covered; transmitters and receivers, lumped element filters, tranmission lines and S-parameters, RF MEMS, RFICs and MMICs, and many others. In addition, the book includes extensive line diagrams to illustrate circuit diagrams and block diagrams of systems, including diagrams and photographs showing how circuits are implemented practically. Furthermore, case studies are also included to explain the salient features of a range of important wireless communications systems. The book is accompanied with suitable design examples and exercises based on the Advanced Design System – the industry leading CAD tool for wireless design. More importantly, the authors have been working with Keysight Technologies on a learning & teaching initiative which is designed to promote access to industry-standard EDA tools such as ADS. Through its University Educational Support Program, Keysight offers students the opportunity to request a student license, backed up with extensive classroom materials and support resources. This culminates with students having the chance to demonstrate their RF/MW design and measurement expertise through the Keysight RF & Microwave Industry-Ready Student Certification Program

Characterisation of the dielectric properties of rubber latex from 0.5 to 33GHz

This paper presents a detailed characterisation of the dielectric properties of rubber latex over the entire microwave frequency range (0.5-33GHz), for samples with a range of dry rubber contents and over the temperature range 10-40°C. The relaxation processes observed are analysed and compared to pure water, as modelled with the Debye equation. It is shown that two relaxation processes exist in rubber latex, with one of these attributed to the presence of bound water molecules. The extended Debye equation is then applied to model the dielectric permittivity. Each relaxation time extracted from the modelling exposes a different physical mechanism in rubber latex. It is believed that this is the most extensive study of the microwave properties of rubber latex yet reported, and that the results are an important step in the development of microwave sensors for determining the quality of rubber latex for agriculture and industrial application

Ultrawideband characterisation of CPW GaAs monolithic 60 GHz couplers using overlaid structures

Novel Coplanar Waveguide (CPW) coupler structures are proposed and successfully implemented at 60 GHz on a GaAs substrate. The proposed structures use a combination of very small gap, made possible by an advanced e-beam direct-write metal patterning process, and silicon dielectric overlays to achieve a tight coupling. In comparison with a CPW Lange coupler, the proposed couplers provide a smaller size and better performances

Differential six-port reflectometer for determining dry rubber content of latex

This study presents the application of a differential six-port reflectometer to the design of a portable system for measurement of the dry rubber content (DRC) of latex. The proposed DRC measurement system consists of a 1 GHz reflectometer used with an open-ended coaxial-probe sensor, a temperature sensor, a display and a microcontroller. The complex permittivity and temperature of the rubber latex are measured, and a temperature-dependent model for DRC determination based on a dielectric mixture theory is used. The reflectometer performance is verified by comparing the measured complex permittivity with the results obtained from a commercial dielectric measurement system. Finally, the accuracy of the DRC measurement system is assessed by comparing the measured DRCs from different latex samples over the range of 10–40°C with the standard oven-drying method