Dr Richard Collier

Honorary Senior Research Fellow

About

Dr Richard Collier is Honorary Senior Research Fellow in the School of Engineering and Digital Arts. 

Publications

Article

  • Azeez, Y. et al. (2019). Establishing a New Form of Primary Impedance Standard at Millimeter-Wave Frequencies. IEEE Transactions on Instrumentation and Measurement [Online] 68:294-296. Available at: https://doi.org/10.1109/TIM.2018.2872499.
    This paper investigates the possibility of using layers of graphene to form primary impedance standards for millimeter-wave rectangular metallic waveguide. It is shown that standards with values of Y?, 2Y? and 3Y? can be produced by a monolayer, bilayer, or trilayer of graphene, respectively, where Y? is the characteristic admittance of the waveguide. These standards could then be used in the calibration of vector network analyzers.
  • Li, D. et al. (2000). Bandwidth enhancement of finline at millimetre-wave frequencies. Electronics Letters [Online] 36:1390-1391. Available at: http://dx.doi.org/10.1049/el:20001013.
    A technique is proposed to extend the bandwidth of a finline at millimetre-wave frequencies. Instead of mounting the slotline in the E-plane in the centre of the waveguide, the slotline is positioned in a plane where the electric field of the TE20 mode is zero. The bandwidth enhancement is calculated analytically and confirmed by rigorous 3D electromagnetic simulation.
  • Reeves, J. et al. (1999). Experimental development of microwave delivery systems for the treatment of oesophageal cancer and Barrett's oesophagus. Gastrointestinal Endoscopy 49:AB131-AB131.
  • Young, P. and Collier, R. (1997). Extension to the effective-index method to include the calculation of losses in dielectric waveguides. Electronics Letters [Online] 33:1151-1152. Available at: http://dx.doi.org/10.1049/el:19970755.
    A simple extension to the effective-index method (EIM) for the solution of lossy dielectric waveguides, whereby the attenuation constant can be calculated, is presented. The method is valid for structures where both the guiding and surrounding regions have dielectric losses. Furthermore, the attenuation constant is given directly from the lossless solution.
  • Young, P. and Collier, R. (1997). A novel wavemeter for dielectric waveguide. European Microwave Conference [Online] 2:891-896. Available at: http://dx.doi.org/10.1109/EUMA.1997.337908.
    This paper presents a novel wavemeter for use with dielectric waveguide. A movable piece of dielectric is placed parallel to a dielectric guide of identical cross section, forming a coupled structure. This causes varying amounts of energy to radiate from the far end of the movable dielectric. By locating the separation which results in maximum radiation loss, the operating frequency can be obtained. Experimental and theoretical results are given and are shown to be in good agreement.
  • Young, P., Collier, R. and Bianconi, P. (1997). A low loss phase shifter for dielectric waveguide using asymmetrical guides. European Microwave Conference [Online] 1:631-635. Available at: http://dx.doi.org/10.1109/EUMA.1997.337755.
    This paper presents a phase shifter for dielectric waveguide. Phase shifting is achieved by varying the distance between the waveguide and a block of dielectric. By calculating the propagation constants of a coupled dielectric slab waveguide an approximate expression for the phase shift is given and is shown to be in good agreement with experimental results.
  • Collier, R. and Ntui, J. (1994). In-Vivo Measurements of the Phase Constants of Transerse Mechnical Waves in a Human Tibia from 100-HZ TO 1000-HZ. Medical Engineering & Physics [Online] 16:379-383. Available at: http://dx.doi.org/10.1016/1350-4533(90)90004-R.
    This paper contains the details of a new technique for measuring the mechanical phase constants of transverse waves in human tibia, in vivo. The measurements are made in the frequency range from 100 to 1000 Hz. The importance other hand, a fractured tibia has a large phase delay at the fracture site. This paper establishes a set of typical phase delays for a range of tibia so that subsequent measurements on fractured patients can be interpreted. It contains a description of the method of measuring the phase delay and a detailed analysis of errors. In particular, it includes an account of the phase delay through the soft tissues as well as the bone and how the former can be eliminated. It is not an exhaustive account of this topic but contains sufficient results to show that the measurements can be made relatively easily. Finally, there is a theoretical model which can be used to predict the phase shift. However, in order to use the model various other measurements are necessary and a direct measurement of phase is easier than using a model.
  • Collier, R. and Dsouza, M. (1992). Phase shifters for dielectric guides PHASE SHIFTERS FOR DIELECTRIC GUIDES. IEE Proceedings H: Microwaves Antennas and Propagation 139:202-204.
    A phase shifter has been designed to give a constant phase over the octave bandwidth 70-140 GHz in dielectric guide. The phase shifter was designed for use in a multistate reflectometer in dielectric guide, though other applications are possible. The multistate reflectometer required two less power meters than a previous six-port reflectometer. The whole device enabled very accurate measurement of phase and amplitude in the range 70-140 GHz for little more than the cost of a swept source.
  • Collier, R. and Dsouza, M. (1992). Comparison of junctions in both dielectric guides and metallic guides above 75 GHz. IEE Proceedings A: Science Measurement and Technology 139:226-228.
    The paper contains a comparison of the return losses caused by misalignment of the junctions in both metallic and dielectric waveguides. The practical measurements of these return losses for dielectric guides show that they are much smaller than the minimum return losses for metallic guides. The paper concludes with a summary of the features of dielectric guide which make it a viable alternative to metallic guide above 100 GHz.

Conference or workshop item

  • Young, P. and Collier, R. (2001). Exact Solution of Lossy Asymmetrical Coupled Dielectric Slab Waveguides. in: 31st European Microwave Conference.
  • Boese, I. and Collier, R. (1997). Measurements on millimetre wave circuits at 140 GHz. in: 8th British Electromagnetic Conference. Iee-Inst Elec Eng, pp. 171-176.
    The paper describes a novel technique for the measurement of monolithic millimetre wave circuits at 140GHz. These circuits are measured using a coplanar waveguide probe which is linked via a dielectric waveguide to a multistate reflectometer. This reflectometer is mounted on a probe station, close to the circuit, and is connected via a flexible dielectric guide to an oscillator. The reflectometer is constructed using dielectric waveguide components and operates from 118 to 178GHz. The paper shows some initial measurements of passive circuit components which are part of a set of coplanar waveguide test circuits on a gallium arsenide substrate at 140GHz. The paper concludes with a discussion of the results.
  • Young, P. and Collier, R. (1996). Low loss phase shifter for dielectric waveguide. in: 2nd High Frequency Postgraduate Student Colloquium. I E E E, pp. 631 -635.
  • Yip, J. et al. Substrate Modes in Double-Layered Coplanar Waveguides. in: 31st European Microwave Conference. pp. 189-192.
  • Jastrzebski, A. et al. The Design of Waveguide-to-Finline Taper Transitions at Millimetrewave Frequences. in: MIKON 2002 14th Interntional Conference on Microwaves, Radar and Wireless Communications.

Thesis

  • Collier, R. (1965). A K-Band ESR Spectrometer using an Ammonia Maser.
    The thesis contains the details of the ammonia maser amplifier which was used to amplifiy and reduce the background noise of ESR signals.
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