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Publications
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This
is where you can find copies of conference papers, technical
information and other company publications.
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"Practical validation of antenna
pattern measurement interference cancellation using a correlation
technique",
IEEE
AP-S 2004, Monterey, CA, USA, 20th - 26th June 2004
Abstract—The ability of correlation
techniques to suppress multipath signals that cause inaccuracies in
antenna pattern measurements has been validated by experiment.
Read the
paper published
on pages 753-758.
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"Correlation
techniques applied to antenna pattern measurement",
IEE Electronics Letters, May 2004
Abstract—Antenna pattern measurements are
often distorted by extraneous signals that reach the test zone as a result
of scattering from obstacles in the vicinity of the antenna range. These
“multipath” signals have to be eliminated or their effects reduced, if
accurate pattern measurements are to be obtained. A number of techniques
that analytically or experimentally compensate for multipath effects are
described in the literature [1, 2] but these are often complicated and/or
expensive to implement. Relatively simple techniques based on signal
processing are available, however [3-5], and have many attractions. In
this correspondence we describe results obtained using a correlation
technique.
Read the
paper
published on pages 572-573.
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"Signal Processing Techniques improve Antenna Pattern
Measurement",
IEE AMS 2004, Loughborough, UK, 25th - 26th May 2004
Abstract—Antenna pattern
measurements are often distorted by extraneous signals that reach the test
zone as a result of scattering from obstacles in the vicinity of the
antenna range. These “multipath” signals have to be eliminated or their
effects reduced, if accurate pattern measurements are to be obtained. A
number of techniques that analytically or experimentally compensate for
multipath effects are described in the literature but these are often
complicated and/or expensive to implement.
In fact, there are
established advanced signal processing schemes that are used in both wired
and wireless communication systems to reduce the effects of multipath
propagation, but until recently these techniques have not been applied to
antenna measurements. Even state-of-the-art antenna ranges seem to have
taken little or nothing from the world of communications engineering,
despite the relative simplicity and attractiveness of the available
techniques.
In this paper we
describe the application of two such techniques, equalization and
correlation, to antenna pattern measurements. The principles are explained
and the ways in which the techniques are applied in practice are
discussed. Practical measurements show that the distortion in pattern
measurement that results from multipath propagation in indoor and outdoor
ranges can be almost completely removed by the use of relatively simple
techniques that are commonplace in another related field i.e.
communications engineering.
Read the
paper published on pages 96-99.
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"Plane
wave spectra, test-zone fields and simulation of antenna-pattern
measurements",
IEE Electronics Letters, December 2003
Abstract—It is shown that a useful and
vivid illustration of the effects of multipath in antenna ranges can be
provided via the plane wave spectrum approach. Transforming from the plane
wave spectrum to the test-zone field requires both a two-dimensional
Fourier transform and a co-ordinate transform, and the test-zone field in
the presence of multipath is then represented by a distorted sphere.
Convolution can be used to predict the measured pattern, given the plane
wave spectrum and the true pattern of the antenna. Alternatively,
multiplication of the test-zone field and the true pattern will yield the
same result.
Read the
paper
published on pages 1780-1782 and obtain the separate
colour figures.
Correspondence resulting from IEEE A&P Magazine paper,
IEEE A&P Magazine, June 2003
Dick Flam (formerly of Flam & Russell, Inc.) has provided some constructive comments on our [IEEE A&P Magazine, April 2003] paper specifically, and more generally in the context of using equalization in antenna ranges."
"Antenna Diversity
for UHF Handportable Radio",
IEE Electronics Letters, June 2003
Abstract—Theoretical and simulation
studies have been undertaken to explain the experimentally-observed
effect that the correlation between the signals obtained from
closely-spaced antennas is smaller than that predicted by well-known
theoretical models. When mutual impedance effects are significant, the
correspondence between signal and field component correlation breaks
down. Taking two parallel dipoles as an example, it is shown that
useful diversity advantage can be obtained with separations of the
order of 0.1λ.
Read the paper published on pages 946-948.
"Equalization
for Antenna Pattern Measurements: Established Technique
— New Application",
IEEE A&P Magazine,
April 2003
Abstract—This paper describes a novel system that overcomes the inaccuracies in antenna radiation pattern measurements caused by multipath propagation. The system operates by specifically correcting for the effects of unwanted signals rather than by attempting to remove, or minimize, them through the use of screens or baffles or an anechoic chamber. An equalization technique is used, the parameters of the equalizer(s) being determined from a special measurement of the antenna range under consideration. The method is generally applicable; it may be implemented ab initio in new indoor or outdoor ranges, or retrofitted to existing ranges to improve accuracy. Most importantly, however, the basic idea leads to the design of a completely new type of real-time 3-D range in which sensors are placed on the surface of an imaginary sphere surrounding the antenna under test (AUT), and an anechoic chamber is not required.
Read the paper published in the AMTA Corner.
"Equalization: A Technique to Improve
the Accuracy of Antenna Radiation Pattern Measurements",
ICAP 2003,
Exeter, UK, 31st March – 3rd April 2003
Abstract—This paper describes a novel system that overcomes the inaccuracies in antenna radiation pattern measurements caused by multipath propagation. The system operates by specifically correcting for the effects of unwanted signals rather than by attempting to remove, or minimize, them through the use of screens or baffles or an anechoic chamber. An equalization technique is used, the parameters of the equalizer(s) being determined from a special measurement of the antenna range under consideration. The technique is generally applicable; it may be implemented ab initio in new indoor or outdoor ranges, or retrofitted to existing ranges to improve accuracy. Most importantly, however, the basic idea leads to the design of a completely new type of real-time 3-dimensional range in which sensors are placed on the surface of an imaginary sphere surrounding the antenna under test (AUT), and an anechoic chamber is not required.
Read the paper presented in session 2B.
"Improved Antenna Pattern Measurements
using Equalisation",
IEE Antennas and Propagation
Newsletter, October 2002
Extract—All antenna engineers know that an antenna under test (AUT) should experience a plane wave field when its radiation pattern is being measured; indeed in an ideal situation the direct propagation path between the range antenna (RA) and the AUT, some distance away, is the only path that exists. This situation is realized in an ideal anechoic chamber and is approximated, over a specified range of frequencies, in practical anechoic chambers. Outdoor antenna ranges are always designed to keep the direct path well clear of natural or man-made obstacles and where problems exist, screens or baffles can be strategically placed to prevent the scattered signals reaching the AUT. However, for a variety of reasons, perfection is never achieved and there are always extraneous (multipath) signals that reach the test zone. These signals perturb the test zone field (TZF) to a greater or lesser extent, and cause inaccuracies in measurement. In many cases the channel characteristics change with time due to movement of the AUT or dynamic changes in the environment.
Read the paper published on pages 4-7.
"Improved Antenna Radiation Pattern
Measurements using an Equalization Technique",
AMTA 2002, Cleveland, Ohio, USA, 3rd – 8th
November 2002
Abstract—This paper describes a novel system that overcomes the inaccuracies in antenna radiation pattern measurements caused by multipath propagation. The system operates by specifically compensating for the effects of unwanted signals rather than by attempting to remove, or minimize, their effects through the use of screens or baffles or an anechoic chamber. Compensation is achieved through the use of an equalization technique, the parameters of the equalizer(s) being determined from a special measurement of the antenna range under consideration. The method is generally applicable; it may be implemented ab initio in new indoor or outdoor ranges, or retrofitted to existing ranges to improve accuracy. Most importantly, however, the basic idea leads to the design of a completely new type of real-time 3-D range in which sensors are placed on the surface of an imaginary sphere surrounding the antenna under test (AUT), and an anechoic chamber is not required.
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