http://www.q-par.com A collection of technical papers written by Q-par Angus staff members. daily 1 2007-10-30T16:27:53Z http://www.q-par.com/corporate/news-and-events/new-theoretical-research-findings Dr Andrew Mackay recently presented a paper on the theory of optimal Radar Absorbent Materials (RAM) at the ICEAA07 Conference in Italy, September 2007. A version of this paper is now included on our web site. Also, two recent submissions for publication to the IET Microwaves, Antennas and Propagation journal. The first is concerned with fundamental bandwidth performance limits to finite antennas. The second is concerned with the dispersion properties and physical realiseability of negative refractive index materials. This second article has been greatly expanded and updated. No publisher Dr Andrew Mackay Information Downloadable Technical Papers 2008-06-09T12:13:11Z News Item http://www.q-par.com/corporate/marketing/dispersion-requirements-of-low-loss-negative-refractive-index-materials Article submitted to IET Microwaves, Antennas and Propagation: "A necessary dispersion requirement is given for the effective relative permeability, μr (ω) and permittivity ǫr (ω) as a function of frequency for lossy homogeneous dispersive materials and negative refractive index materials in particular, if they exist at some dimensional scale D. The requirements are valid both for isotropic and uniaxial materials, the latter defined by material properties that are invariant under a rotation about a principal axis. Using asymptotic requirements at zero frequency and Foster’s reactance theorem, the general band-gap structure is given for low-loss materials. It is shown that such materials can only be achieved if the material exhibits finite band-gaps separating regions of positive and/or negative refractive index regions. In degenerate cases the band gaps shrink to zero but low-loss propagation remains impossible in the neighbourhood of the critical frequencies. The effect of small losses are considered, and compared with Stockman’s criterion. Losses may be arbitrarily small within a band provided there are no bounds to the size of the real parts of the relative permittivity and permeability at the band edges. A numerical example is given showing the effect of small losses. No publisher andrewm Information Downloadable Technical Papers 2008-06-09T11:31:48Z File http://www.q-par.com/corporate/marketing/the-theory-and-design-of-provably-optimal-bandwidth-radar-absorbent-materials-ram-using-dispersive-structures-and-or-frequency-selective-surfaces-fss Published in the Proceedings of the 2007 International Conference on Electromagnetics in Advanced Applications (ICEAA07), September 2007. This article concerns the design of radar absorbent materials which are theoretically optimal in the sense of maximum reflection loss for a material of given bandwidth and thickness. It covers the theory, definition of benchmarks and design methodology. No publisher andrewm Downloadable Technical Papers 2007-10-30T16:37:33Z File http://www.q-par.com/corporate/marketing/a-lightweight-ultra-wideband-polarimetric-w-band-radar Abstract - A lightweight, ultra wideband (UWB), polarimetric millimetre wave 94 GHz radar with high resolution is described for environmental and other short range applications. UWB and random signal W-band radar technologies are combined with polarimetric and super-resolution processing techniques to provide a compact remote sensing capability that is manportable. An all-weather capability is provided for accurate and high resolution measurement of the physical size, relative distance, bearing, altitude, direction, velocity and classification of stationary and moving objects at ranges of less than 10 km. Attributed information relating to the sensed environment such as local surface features, water depth, terrain topology and object classification is derived from remote millimetre wave radar measurements including polarisation. No publisher duncanw Downloadable Technical Papers Presentations 2007-10-30T16:38:15Z File http://www.q-par.com/corporate/marketing/uwb-passive-microwave-imagery-from-static-discharge-effects Paper published in the IEE Electronics Letters, Vol 40, No. 18, 2nd Sept. 2004 by Dr Andrew Mackay of Q-par Angus Ltd. No publisher andrewm Downloadable Technical Papers 2007-10-30T16:38:54Z File http://www.q-par.com/corporate/marketing/copy_of_wideband-antennas-an-historical-perspective Presented at IEE Symposium in September 2005, this paper looks at the evolution of wideband antennas and uses modern day techniques to examine performance of early antennas. There are two files, the article and poster presentation. This is the main article. No publisher Dr Richard Holliday Downloadable Technical Papers 2007-10-30T16:40:56Z File