Generalized Parity-Time Symmetry Condition for Enhanced Sensor Telemetry

Wireless sensors based on micro-machined tunable resonators are important in a variety of applications, ranging from medical diagnosis to industrial and environmental monitoring.The sensitivity of these devices is, however, often limited by their low quality (Q) factor.Here, we introduce the concept of isospectral party time reciprocal scaling (PTX) symmetry and show that it can be used to build a new family of radiofrequency wireless microsensors exhibiting ultrasensitive responses and ultrahigh resolution, which are well beyond the limitations of conventional passive sensors. We show theoretically, and demonstrate experimentally using microelectromechanical based wireless pressure sensors, that PTXsymmetric electronic systems share the same eigenfrequencies as their parity time (PT)-symmetric counterparts, but crucially have different circuit profiles and eigenmodes. This simplifies the electronic circuit design and enables further enhancements to the extrinsic Q factor of the sensors

Utilisation of microsystems technology in radio frequency and microwave applications

The market trends of the rapidly growing communication systems require new product architectures and services that are only realisable by utilising technologies beyond that of planar integrated circuits. Microsystems technology (MST) is one such technology which can revolutionise radio frequency (RF) and microwave applications. This article discusses the enabling potential of the MST to meet the stringent requirements of modern communication systems. RF MST fabrication technologies and actuation mechanisms empower conventional processes by alleviating the substrate effects on passive devices and provide product designers with high quality versatile microscale components which can facilitate system integration and lead to novel architectures with enhanced robustness and reduced power consumption. An insight on the variety of components that can be fabricated using the MST is given, emphasizing their excellent electrical performance and versatility. Research issues that need to be addressed are also discussed. Finally, this article discusses the main approaches for integrating MST devices in RF and microwave applications together with the difficulties that need to be overcome in order to make such devices readily available for volume-production.peer-reviewe

A Tunable Ferrofluid-based Polydimethylsiloxane (PDMS) Microchannel Inductor for Ultra High Frequency Applications

In this work, a tunable ferrofluid-based polydimethylsiloxane (PDMS) microchannel inductor with high quality factor and high tuning range is proposed. For this project, PDMS is used to create a microchannel with a width and height of 0.53 mm and 0.2 mm respectively. The microchannel is then used to cover the whole design of a solenoid inductor. A solenoid inductor is designed using wire bonding technique where lines of copper and bond wires are used to form a solenoid winding on top of silicon substrate. A light hydrocarbon based ferrofluid EMG 901 660 mT with high permeability of 5.4 is used. The ferrofluid-based liquid is injected into the channel to enhance the performance of a quality factor. A 3D full-wave electromagnetic fields tool, ANSYS HFSS is used in this work to simulate the solenoid inductor. The results obtained in this work gives a quality factor of more than 10 at a frequency range of 300 MHz to 3.3 GHz (Ultra High Frequency range). The highest quality factor is 37 which occurs at a frequency of 1.5 GHz, provides a high tuning range of 112%

Octave-tunable miniature RF resonators

The development and testing of a miniaturized, high-Q, broadly tunable resonator is described. An exemplary device, with a center frequency that is continuously tunable from 1.2 to 2.6 GHz, was tested in detail. Experimental results demonstrated a resonator Q of up to 380, and typical insertion loss of -1.9 dB for a 25 MHz 3-dB bandwidth. These resonators have been used to stabilize a broadly-tunable oscillator with phase noise of -132 dBc/Hz at 100-kHz offset, with a center frequency tunable from 1.2-2.6 GHz, and a tuning speed of 1 GHz/ms

1.45GHz-1.55GHz Tunable RF Band-pass Filter

RF signals are used in the communication field in general. It has special band called microwave band which is the focus of this project. The idea of filtering comes from the need to transmit certain frequency of ranges of interest and block others. In this project the focus is on tunable filters using MEMS idea to solve the problem of complexity and price of the conventional tunable filters. The project focuses on L band to get the range from 1.45GHz to 1.55 GHz. The project starts by designing the low pass prototype and convert it to comb-line filter to find the capacitance range for the design of the tuneable capacitor using CMOS-MEMS technology. The tunable capacitor has to be modelled and designed. Theoretical modelling and ADS simulation determined the tuning range required for the capacitor is from 1.72pF to 1.84pF. A CMOS-MEMS fixed and tuneable capacitors were designed and simulated to achieve this range of capacitance and requires a voltage of 20V for tuning. Thus the objectives of the study have been achieved successfully and recommendations are made to achieve a wider frequency range for the filter and for integration of the filter with the tunable capacitor

Radio Frequency Microelectromechanical Systems in Defence and Aerospace

For all onboard systems applications, it is important to have very low-loss characteristics and low power consumption coupled with size reduction. The controls and instrumentation in defence and aerospace continually calls for newer technologies and developments. One such technology showing remarkable potential over the years is radio frequency microelectromechanical systems (RF MEMS) which have already made their presence felt prominently by offering replacement in radar and communication systems with high quality factors and precise tunability. The RF MEMS components have emerged as potential candidates for defence and aerospace applications. The core theme of this paper is to drive home the fact that the limitations faced by the current RF devices can be overcome by the flexibility and better device performance characteristics of RF MEMS components, which ultimately propagate the device level benefits to the final system to attain the unprecedented levels of performance.Defence Science Journal, 2009, 59(6), pp.568-567, DOI:http://dx.doi.org/10.14429/dsj.59.156