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High Frequency Postgraduate Student Colloquium, 1999

Date 17-17 Sept. 1999

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Displaying Results 1 - 25 of 27
  • MTT/ED/AP/LEO Societies Joint Chapter United Kingdom and Republic of Ireland Section. 1999 High Frequency Postgraduate Student Colloquium (Cat. No.99TH8409)

    Publication Year: 1999
    Request permission for commercial reuse | PDF file iconPDF (143 KB)
    Freely Available from IEEE
  • New model for the effective permeability of ferrite microstrip

    Publication Year: 1999, Page(s):105 - 110
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (192 KB)

    This work is to develop a new model for the effective permeability of ferrite microstrips which is based on Wheeler's (1977) microstrip impedance model. The newly developed model for the effective permeability will have some improvements over the well-known model developed by Pucel and Masse (1972). In this model, the transition error (or the discontinuity) from a narrow to wide ferrite microstrip... View full abstract»

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  • Self-steering arrays for mobile communications

    Publication Year: 1999, Page(s):99 - 104
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (288 KB)

    This paper discusses various architectures for self-steering arrays. The research work performed involved examining the principle of phase conjugation engaged in active self-steering arrays; and the output of a mixer after frequency down conversion was investigated for possible RF leakage signal. This study, together with theoretical simulations of self-steering arrays modelled in Matlab, led to s... View full abstract»

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  • Characterization and reduction of edge leakage current in AlGaAs/GaAs heterojunction bipolar transistors for high frequency applications

    Publication Year: 1999, Page(s):93 - 98
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (304 KB)

    N-p-n AlGaAs/GaAs heterojunction bipolar transistors of various emitter-mesa diameters have been fabricated to investigate the dependence on structural design considerations of the edge leakage current, mainly caused by surface recombination. It is shown that the inclusion of a thinned-emitter edge shoulder structure has a significant effect on the mesa edge leakage current of circular devices. MO... View full abstract»

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  • A KA band MMIC oscillator incorporating a novel injection locking circuit

    Publication Year: 1999, Page(s):158 - 163
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (216 KB)

    A GaAs MMIC oscillator operating around 34 GHz has been designed and tested. This circuit incorporates a novel type of on-chip injection locking configuration, removing the requirement for off-chip couplers/circulators which would normally be required for typical reflection type injection locking applications. This configuration provides a separate injection locking port on the MMIC by utilising t... View full abstract»

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  • A wide-band microstrip series array at MM-wave

    Publication Year: 1999, Page(s):88 - 92
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (180 KB)

    A design methodology is outlined for planar microstrip series fed arrays with emphasis on the MM-wave region of the frequency spectrum. The array comprises a linear arrangement of microstrip patches with each patch loading the preceding patch in succession and finally terminated in a matched load. A new technique incorporating variations of patch width to feed line width yields bandwidths in exces... View full abstract»

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  • Sub-THz passive harmonic mode-locking effects in monolithic and external-reflector compound cavity laser diodes

    Publication Year: 1999, Page(s):152 - 157
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (280 KB)

    Passively harmonic mode-locked laser diodes are capable of generating pulses at repetition rates in excess of 1.5 THz. Harmonic mode-locking techniques fall into two main categories: colliding pulse mode-locking (CPM) and compound cavity mode-locking (CCM). The (asymmetric) CPM effect has previously been used to achieve mode-locking at frequencies up to 860 GHz. Various CCM constructions were prev... View full abstract»

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  • Flip chip interconnect analysis at millimetre wave frequencies

    Publication Year: 1999, Page(s):82 - 87
    Cited by:  Papers (2)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (260 KB)

    This paper examines the variation of RF performance on a flip chip due to changes in bump height, bump position, bump shape and number of bumps per interconnect. A full 3D electromagnetic simulator is used extensively to compute the scattering parameter response, impedance and electric field distributions. Varying the bump height will change the reflection coefficient and return loss at millimetre... View full abstract»

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  • Improved CAD for the design of novel microstrip antenna structures

    Publication Year: 1999, Page(s):2 - 7
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (220 KB)

    A finite difference time domain (FDTD) model is developed and validated against measured data for rectangular microstrip antennas. The FDTD model is then used as the fitness function in a genetic algorithm (GA). The GA-FDTD code is used to optimise a known patch antenna configuration and to evolve the same configuration starting with very limited knowledge. This was carried out to study the `searc... View full abstract»

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  • Ferrite loaded dielectric waveguides for millimeter wave applications

    Publication Year: 1999, Page(s):42 - 47
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (252 KB)

    Many millimetre-wave non-reciprocal components have been developed, utilising special properties of dielectric/dielectric or dielectric/ferrite interfaces and the non-reciprocal behaviour of ferrites under different biasing conditions. The aim of this paper is to determine, observe and summarise the fundamentals behind the theory in order to build a non-reciprocal millimetre and/or optical wavegui... View full abstract»

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  • An SIS focal plane imaging array for 350 GHz

    Publication Year: 1999, Page(s):146 - 151
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (244 KB)

    Astronomical interest in millimetre and submillimetre wavelengths (f=300 GHz to 1 THz) has fuelled the development of low noise high sensitivity detectors for these wavelengths. HARP (Heterodyne Array Receiver Project) will be a 16 element focal plane imaging array of heterodyne detectors for the 850 micron (325-375 GHz) band. Each element will consist of a mixer employing an SIS (superconductor i... View full abstract»

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  • Low cost beam steered arrays for mobile communications

    Publication Year: 1999, Page(s):74 - 79
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (196 KB)

    This paper discusses the development of a low cost beam steering array from the mathematical analysis through to the testing of the first prototype. A mathematical analysis program was developed for calculation of phase steered antenna array behaviour based on antenna array equations. Simulated results from this program show that a very large antenna array would be required to create relatively sm... View full abstract»

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  • Automotive millimetre wave radar measurement

    Publication Year: 1999, Page(s):34 - 39
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (236 KB)

    This paper presents a method of radar backscatter measurement from a road for automotive applications and discusses the signal processing and the transformation from polar to Cartesian domain on the recorded radar data. The data was produced using a scanned 94 GHz radar sensor with 26° field of view with maximum range constrained to 160 m. A quantitative feel for the representative parameters ... View full abstract»

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  • Theoretical analysis of the Pickett Potter horn-reflector antenna for submillimetre-wave applications

    Publication Year: 1999, Page(s):139 - 144
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (212 KB)

    A Pickett-Potter (1984, 1963) horn-reflector feed for short wavelength (>700 GHz) SIS mixer has been theoretically designed and a 15 GHz scale model of a Pickett-Potter horn has been developed and tested. The antenna comprises of offset parabolic reflector fed by a Pickett-Potter horn. The horn is easy to machine, and yet still preserves the desirable electrical properties of a corrugated horn,... View full abstract»

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  • Extraction of dielectric properties of building materials from free-space time-domain measurement

    Publication Year: 1999, Page(s):127 - 132
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (220 KB)

    Both the reflectivity and transmissibility of the building materials are dominant factors to the propagation of radio signal within indoor environments. As these parameters are strongly related to the dielectric properties of building materials, they can be obtained only when the building materials are well characterised. This paper describes an approach to extract the dielectric properties of bui... View full abstract»

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  • Modelling spectral regrowth and the effect of packet size

    Publication Year: 1999, Page(s):68 - 73
    Cited by:  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (176 KB)

    Traditionally nonlinearity has been characterized by two-tone intermodulation distortion. However, for digital radio, modelling spectral regrowth is much more important. There is currently much interest in modelling spectral regrowth in microwave power amplifiers for wireless communications. The ability to predict spectral regrowth or, more specifically, adjacent channel power ratio (ACPR), has a ... View full abstract»

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  • Synthesis technique for ceramic block cup capacitances using Schwarz-Christoffel transformation

    Publication Year: 1999, Page(s):111 - 115
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (140 KB)

    The Schwarz-Christoffel transformation is applied to an irregular cup shape used to produce coupling capacitances in monoblock ceramic filter structures. The transformation is developed to yield a synthesis technique to determine the cup geometry from a specified capacitance. Calculations compare well with another numerical method. The derived method is a useful tool for dimensional tolerance anal... View full abstract»

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  • Genetic algorithm using real parameters for array antenna design optimisation

    Publication Year: 1999, Page(s):8 - 13
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (264 KB)

    The use of genetic algorithms (GAs) in the design of antennas has become increasingly popular. This is due to their versatility and ability to perform a rigorous search in complex multi-modal search spaces. Much attention has previously been placed on binary genetic algorithms. However, few authors have looked at the use of continuous (decimal) genetic algorithms, particularly for antenna design. ... View full abstract»

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  • A novel dual-mode TE01δ dielectric resonator

    Publication Year: 1999, Page(s):48 - 53
    Cited by:  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (216 KB)

    A new dielectric resonator (DR) consisting of two orthogonal hollow dielectric cylinders, is presented. The structure is found to support a pair of degenerate modes each having a field pattern very similar to the TE01δ mode supported by a cylindrical DR. Measurement of the unloaded Q-value indicates a performance similar to that of single cylindrical DR, with a ratio of spurious t... View full abstract»

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  • Characterisation and performance of high power packaged devices

    Publication Year: 1999, Page(s):133 - 138
    Cited by:  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (228 KB)

    This paper presents a measurement system that combines the capabilities of a vector network analyser, load and source pull and time domain measurement in a single test-bench. The system is based upon the microwave transition analyser (MTA) and a high power test fixture which was designed in-house. The user may optimise the load and source impedance for best desired performance, output power, gain ... View full abstract»

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  • Design of a millimetre-wave mixer for broadband mobile communications

    Publication Year: 1999, Page(s):28 - 33
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (232 KB)

    The design process for a state-of-the-art millimetre-wave down converter from 65.5 GHz to 1.5 GHz is described in detail. The work starts with a short discussion of basic mixer theory and its implications on the performance for any mixer and then moves on to the problem of choosing the correct topology for a given task. Some of the specific problems encountered at millimetre-wave frequencies are d... View full abstract»

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  • Low intermodulation amplifier for PHS applications

    Publication Year: 1999, Page(s):116 - 119
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (232 KB)

    An amplifier where the third order IM distortion has been reduced is proposed. If two signals at different carrier frequencies are incident at the input of an amplifier, due to the nonlinearity, these signals will interact with each other and the output will contain additional signals at all combinations of sum and difference of these frequencies, which are IM products. The injection of the second... View full abstract»

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  • Dynamically adaptive microwave structures

    Publication Year: 1999, Page(s):54 - 59
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (240 KB)

    This paper examines candidate configurations for a smart radar absorber or reflector which is capable of self-tuning and perform while scan operation. The discussion is supported by both modeled and measured data View full abstract»

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  • Design of TEM horn antennas for impulse radar

    Publication Year: 1999, Page(s):120 - 126
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (284 KB)

    As it is well known, TEM horns are antennas that can achieve wideband characteristics over multiple decades. This special characteristic of these antennas makes them really attractive for wideband radar/communication systems, where short time-domain pulses of a very wide frequency range are employed. Although these antennas have been investigated by a number of researchers over the last 25 years, ... View full abstract»

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  • A discussion of the effects of amplifier back-off on OFDM

    Publication Year: 1999, Page(s):14 - 19
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (240 KB)

    There has been increased interest in high data rate indoor communications systems using orthogonal frequency division multiplexing (OFDM). This paper details both simulation and experimental results, regarding the sensitivity of such signals to amplifier nonlinearities. In particular the relationship between BER degradation and required amplifier back-off for a given 1 dB compression and IP3<... View full abstract»

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