Patrik Persson

Calculating the mutual coupling between apertures on a convex circular cylinder using a hybrid UTD-MoM method

The problem of calculating the mutual coupling between apertures on a perfectly conducting circular cylinder is considered. The mutual coupling is calculated by a combination of the uniform theory of diffraction (UTD) and the method of moments (MoM). This hybrid method makes it possible to include higher order aperture modes in order to improve the accuracy. It is found that the UTD-MoM solution gives accurate results, even for small cylinders. The results are verified against results found in the literature, as well as against measurements performed at Ericsson Microwave System in Molndal, Sweden. For this purpose, a cylindrical test antenna with 54 apertures was built. Using a single-mode approximation, good agreement, down to about -60 dB, with comparisons to measured data has been obtained. If additional modes are added the results improve significantly, both in amplitude and phase. In several cases, the agreement is good down to coupling levels of about -80 dB. This requires that about six modes are included. However, the most important mode, besides the fundamental TE/sub 10/ mode is the TM/sub 11/ mode.

Efficient Analysis of Aperture Antennas on Generally Shaped Convex Multilayered Surfaces Using a Hybrid SD-UTD Method

A novel hybrid method is described for analyzing convex multilayered conformal array antennas. The hybrid method is based on the spectral domain approach in combination with the ray-based uniform theory of diffraction (UTD) method. The analysis is divided in two parts. First, the spectral domain approach is accelerated by using an asymptotic extraction technique where the extracted term of the Greens function is calculated using UTD. It is shown that this new approach results in significant acceleration of the existing spectral domain algorithm without losing accuracy. The modified spectral domain method is then used in the second part where generally shaped convex multilayered surfaces are analyzed by using sets of canonically shaped surfaces (spheres and/or circular cylinders). Their radii are obtained using the UTD formulation, which contains important information such as distance and curvature of the generally shaped surface along each geodesic. The results obtained using the new algorithm are compared to the available results (calculated and measured) for different conformal antennas, showing very good agreement.

Higher Order MIMO Outdoor-to-Indoor Measurements Using Repeaters

In this paper we present results from a outdoor-to-indoor MIMO measurement campaign where we study the effect of repeaters on singular values, spatial richness, capacity, and delay spread distributions. We present results from different repeater scenarios such as, e.g. different outdoor/indoor repeater deployments with single/dual polarized antennas. The measurements show that repeaters significantly enhance the received SNR while they increase the delay spread and decrease the spatial richness of the MIMO channel. However, the main conclusion is that a significant increase in channel capacity is attained when deploying repeaters mostly thanks to their ability to provide spatial multiplexing over the high-quality eigenmodes they may provide. The number of such eigenmodes is limited by the number of repeaters, deployment, and their antennas.

Efficient technique for mutual coupling calculations between apertures on a PEC circular cylinder covered with a dielectric layer

An efficient and accurate asymptotic Greens function is developed, which will be used to calculate the surface fields excited by tangential magnetic sources on the surface of a PEC circular cylinder that is covered with a dielectric layer. With this knowledge it is possible to calculate the mutual coupling between waveguide fed apertures located on the PEC surface. Note that the efficiency and accuracy of the method strongly depends on the computation of the Greens function.

Hybrid Spectral Domain - UTD method applied to conformal antenna analysis

A hybrid spectral domain - UTD method (Uniform Theory of Diffraction) developed for the analysis of conformal antennas is presented in this paper. The basic idea behind the hybrid method is to combine different analysis methods for conformal antennas and, at the same time, preserve the advantages of the considered methods. More specifically, the considered hybrid SD - UTD method joins the possibility of analyzing multilayer structures (spectral domain method) and the possibility of analyzing electrically large structures (UTD method). Hence, using the developed method it is possible to analyze large multilayered conformal antennas with high accuracy and speed. This work has been made possible by the ACE program for structuring the research on conformal antennas in Europe. The developed method is a result of joining research activities of University of Zagreb, Croatia and the Royal Institute of Technology, Sweden.

Characteristics of a broad-band wide-scan fragmented aperture phased array antenna

In this paper a phased array antenna is described that is designed with the help of a genetic algorithm for scan angles out to 60° from broadside. The focus is on simplifying the manufacturing of the diagonally adjoining pixels and on numerical results for thin antennas. The effects of the corner to corner contacts are studied and results for two synthesized elements ar Test and measurement requirements on wireless devices

Overview of the software integration activities within ACE

The ACE project initiated the start of several integration activities between European institutions involved in electromagnetic modeling of antennas with planar or conformal topologies. The goal of the integration activities was / is not to create a global software package that integrates the software of all partners, but to initiate a long term process for antenna software integration activities within the European antenna community. During the first two years of ACE the integration activities were performed in several groups with a rather small number of partners in each group. The groups were formed by partners who wanted to integrate a specific approach developed by one partner into the software code of another partner. This allows increasing the capability and efficiency of a software code. In this paper a short overview of all integration activities is given.