S.R. Saunders

Meander line technique for size reduction of quadrifilar helix antenna

A method to reduce the axial length of a conventional printed quadrifilar helix antenna (PQHA) using a meander line technique is described. The design approach and the measurement results for the meander printed quadrifilar helix antenna (MPQHA) are presented. A 53% size reduction and considerable bandwidth increase of a conventional PQHA is achieved by using this technique.

Characterization of Polarization Diversity at the Mobile

Two new models used to characterize polarization diversity at the mobile are presented and discussed. The first model is built upon existing theoretical models at a base station to demonstrate how those principles apply to the mobile fading environment. Due to limitations of antennas at the mobile, this extended model, although relevant, is not sufficient to characterize polarization diversity of the antennas; therefore, this paper moves on to show how a new approach to polarization diversity at the mobile exists as an inherent feature within an angular diversity system. Results show that, for two polarizations in a fading environment, the best overall output occurs with a plusmn45deg element configuration, although the diversity combiner itself has optimum performance with a plusmn67.5deg configuration due to lower correlation at the input. The second model is also used to demonstrate how differently polarized dipoles are using polarization diversity inherent within an angular diversity system.

Narrowband fading analysis of indoor distributed antenna systems

The paper presents the effects of distributed antenna systems (DAS) on the Rice K factor by using practical measurements, in order to investigate the degree of possible fading degradation caused by the incoherent signal combination of the conventional DAS architecture. The measured distributions are compared with the theoretical Rice distribution and it is seen that there is no strong indication to consider any other distributions. It is found that the DAS system slightly decreases the K factor, but not sufficiently to have a detrimental effect on availability. Therefore, it is inferred that the dominant effect of DAS is to provide macro-diversity gain.

A comparison of the accuracy of propagation models using hit rate analysis

A new way of gauging the accuracy of radiowave propagation models is presented. The prediction models used are the parabolic equation (PE) and a new slope-uniform theory of diffraction (slope-UTD). The results from these models applied to a terrain database are compared to experimental data from the University of Aalborg, Denmark. This comparison is enabled by using newly defined hit rate metrics. Hit rate metrics are obtained by comparing the predicted and measured availability on a point-by-point basis at a given path loss threshold. The hit rate metric is complementary to first order statistics such as mean and standard deviation of error, in determining the accuracy of a model.

Simultaneous indoor propagation measurements at 17 and 60 GHz for wireless local area networks

A study of indoor propagation factors at 17 and 60 GHz is described. A dual narrowband sounder is described, aimed at evaluating the coverage and frequency reuse potential of these bands. A number of different indoor environments are under investigation from office type buildings containing a large number of small rooms, to a large open plan environment containing no internal walls. Also under investigation are the reflection and transmission characteristics of several construction materials at the same frequencies.

Accurate performance analysis of indoor distributed antenna systems for W-CDMA

Performance analyses of in building distributed antenna (DA) systems for W-CDMA are presented. Uplink and downlink outage probabilities are related to the transmitted power, the shadowing statistics and the loading of the cell and it is observed that by deploying DA in a multi-floor environment the advantages in terms of both coverage and capacity are significant. However, capacity limitations are present due to the noise rise of home cell power controlled interferers, which give rise over thermal noise. In order to overcome these limitations two more flexible architectures, namely zoning and switching, are presented and compared.

A deterministic outdoor to indoor propagation modelling approach

A modelling approach is presented, based on a modified form of the Fresnel diffraction integral. The approach combines contributions through different building elements and interfaces, e.g., windows, walls and doors, in order to-calculate the overall signal contributed to a certain point inside a building. The method could be used to investigate coverage and interference issues when overlaying line of site microcells with in-building picocells or similar scenarios where there is a line of site with the building of interest. Two different cases are considered depending on the receiver position within the building. The first case refers to a receiver position in the first room next to the external wall, while the second case refers to a position anywhere else in the building. The predicted results are compared with a set of measured data recorded in 3 different UK cities.

Autonomous positioning system for indoor propagation measurements

A mobile robot platform has been developed to improve the accuracy of characterisation of the indoor propagation channel. The aim of the system is to provide an accurate mechanism for determining absolute position of the robot within acceptable error bounds, especially where alternative positioning methods, such as GPS, are not available. This paper describes the design, operation and tests performed with the designed robot.

The design of specifications for satellite PCN handheld antennas

The relation between the pattern shape and the performance of an SPCN handheld antenna is examined based on the relation between the environment and the noise received by the antenna. Typical quadrifilar helix antenna patterns in different environments were used to calculate the received noise and to evaluate the performance of these antennas for the ICO satellite system.

Prediction of downlink effective statistical G/T in satellite PCN handsets

The figure of merit (G/T) is one of the major contributors to the calculation of system performance for an Earth-space link. The effective statistical G/T (ESGuT) is introduced as the most useful measure of a handheld terminal performance in a satellite PCN system operated using non-geostationary satellite constellations. A calculation procedure for the ESGuT is presented and used to compare the impact of different antenna pattern shapes, satellite constellations, environments and the influence of the orientation of the handheld.