Showing papers by "Paul R. Young published in 2018"

Chipless Liquid Sensing Using a Slotted Cylindrical Resonator

Abstract: A method for the wireless sensing of the permittivity and level of liquids is presented. The use of a simple, thin-film slotted cylindrical cavity wrapped around a standard polytetrafluoroethylene pipe is proposed. Wireless interrogation of the slot excites a resonant mode whose frequency is dependent on the liquid currently present within the pipe. The proposed method allows for measurements to be taken in situ with no requirement for taking samples of potentially hazardous liquids. The device is capable of sensing materials of high relative permittivity, including water, as well as very lossy liquids. A comprehensive set of results is presented, including measurements of butanol, ethanol, methanol, and water, for several device configurations. The proposed sensor is also shown to be sensitive to small changes in liquid level, allowing for accurate water-level measurements down to 0.1 ml. This sensor is a good candidate for very low-cost, low-complexity real-time monitoring of liquids.

High-gain narrow-band slotted antenna based on ENZ SIW structure

Abstract: The development of a Slotted Substrate Integrated Waveguide Antenna with Epsilon Near Zero material is presented. Here, Epsilon Near Zero (ENZ) waveguide structure is used in the design. The ENZ material used to realize unconventional tunneling of electromagnetic energy with ultra-thin subwavelength channels and it is considered to attain a highly directive narrow band antenna. The effect of the various parameters of the antenna is studied by simulation. A prototype is fabricated and the measurement results are compared with the simulated values.

Wideband high-gain millimetre/submillimetre wave antenna using additive manufacturing

Abstract: This study presents a novel design of a wideband high-gain resonant cavity antenna (RCA) for millimetre and submillimetre wave bands, and its fabrication using additive manufacturing (AM). The proposed RCA antenna consists of a partially reflecting surface and three impedance matching layers fed by a waveguide. AM techniques are utilised to fabricate the design operating at 30 GHz. Two fabrication techniques are assessed for printing the antenna. The first technique is based on printing a dielectric material and fully coating the parts with a metallic layer, while the second technique involves printing the parts in a single process using metal three-dimensional printing. The first technique offers a lightweight solution while the second technique can print the whole model in one run. The antenna design is investigated by both simulations and experiments. The measured results show a 3 dB gain bandwidth of about 10%, and high gain over 15 dBi for all the three resulting antennas. Good agreement between simulation and measurement is obtained. The antenna is of low cost and achieved good performance in terms of wide bandwidth and high gain, thus it is potentially useful for high-speed wireless communications at millimetre-wave and sub-millimetre-wave frequencies.

The Variation of the Attenuation Constant of Low-Loss Transmission Lines in the Presence of Standing Waves

Abstract: A mathematical description of the variation of the attenuation constant in the presence of standing waves is presented. This letter proposes equations describing such phenomena, formulated from basic transmission line analysis. The results could be used to correct errors in precision microwave measurements. Both dielectric and resistive losses are considered, followed by a study of frequency dependence. Practical results of fabricated microstrip lines are presented with comparison to the derived theory.

Modelling of Solution Processed Indium Arsenide Nanowire Microwave Switches

Abstract: This paper presents the modelling of a coplanar-waveguide bottom-gated FET switch using indium-arsenide nanowires. The nanowires have been included on the switch using dielectrophoresis, which is a solution processable technique. This is a necessary first step towards developing a fully printable switch on a flexible substrate, for low cost microwave devices, built using additive manufacturing methods. The measured S-parameters show the switching capabilities of the device with an insertion loss of 9 dB, when the switch is open (gate voltage $\geq \mathbf{60}\ \mathbf{V}$ ). The development of a distributed circuit model that matches the measured data is described, alongside the calculated network parameters used to represent the coplanar-waveguide and the nanowires. The model fits the measured results within 8%, making it suitable for inclusion in a CAD based circuit simulator.