A. Vasylchenko

Quality Assessment of Computational Techniques and Software Tools for Planar-Antenna Analysis

The goal of this paper is a thorough investigation of the quality of the software tools widely used nowadays in the field of planar-antenna analysis and synthesis. Six simulation tools - five well-known commercial tools and one developed in-house - are compared with each other for four different planar antennas. It is crucial to point out that all possible efforts have been made to guarantee the most optimal use of each of the software packages, to study in detail any discrepancies between the solvers, and to assess the remaining simulation challenges. The study clearly highlights the importance of understanding EM simulation principles and their inherent limitations for antenna designers. Finally, some designing guidelines are provided that also can simplify the initial selection of EM solvers.

A dedicated technique to measure shielding effectiveness of textiles using a two‐horn antenna set‐up

In response to the concern about growing electromagnetic radiation levels, special clothes, bedcovers, and curtains made from shielding textiles are already available. In some cases claimed shielding properties are incredibly high. The goal of this paper is to introduce a simple measurement method dedicated to textiles. A free space two‐horn set‐up in combination with a post‐processing technique is used to determine shielding effectiveness. At higher frequencies, a simple wireless link with two horn antennas can be used. This type of measurement tends to show high oscillations, especially when the samples are in the order of a wavelength or smaller. This is due to multiple reflections and diffractions. These oscillations can be smoothened using fitting techniques or a post‐processing procedure based on a simulated Gaussian pulse in time domain. The proposed procedures are tested for different textile topologies in the frequency range 1–5 GHz.

Series-fed microstrip antenna arrays operating at 26 GHz

In point-to-point communication systems, such as satellite communication, antenna with high directivity is needed. The most common way of achieving this requirement is to arrange a number of single elements in an array configuration. The elements of the array are connected using a feeding network. There are two main types of feeding networks, namely: the corporate network and the series feeding network. In the corporate feeding network, there is a free equal path from the source to each of the radiating elements without passing through any other radiator. On the other hand, in the series-fed array the radiators are connected to the same feeding line, such that each element takes its own power and delivers the rest to the next elements. The corporate feeding network provides wider bandwidth than the series feed. A unique feature of the series-feed network is that it allows for titling the main beam of the array via slightly varying the frequency. This range of titling is limited by the bandwidth of the elements and the feeding network.

Design and Parametric Analysis of a Very Compact UWB Antenna with Band Rejection Feature

This paper presents several planar monopole antennas with a very compact size for UWB wireless applications. A systematic study of several topology feature was briefly reported. As a result two UWB antennas with a band rejection property with optimized parameters were proposed.This allows the antennas to cover the entire UWB frequency range, while not interfering with WLAN applications.The reported antenna has a very compact size and includes various features which are characterized in this paper.

A very compact CPW-to-CPS BALUN for UWB antenna feeding

This paper considers an UWB balun optimized for a frequency band from 6 to 8.5 GHz. The balun provides a transition from unbalanced coplanar waveguide (CPW) to balanced coplanar stripline (CPS), which is suitable for feeding broadband coplanar antennas such as Vivaldi or bow-tie antennas. It is shown, that applying a solid ground plane under the CPS-to-CPS transition enables decreasing its area by a factor of 4.7. Such compact balun can be used for feeding uniplanar antennas, while significantly saving substrate area. Several transition configurations have been fabricated for single and double-layer configurations. They have been verified by comparison with results both from a full-wave electromagnetic (EM) simulation and experimental measurements.

Benchmarking of software tools for small planar antenna analysis

Within the framework of the European Network of Excellence on Antennas ACE, in 2005 the working group on software initiated a benchmarking action. At the Katholieke Universiteit Leuven this lead to a thorough investigation of six simulation tools, five well-known commercial ones and one in-house developed. They were confronted with each other for four different antennas. Two of these antennas can be considered “small antennas”. It is crucial to point out that all possible efforts have been done to guarantee the most optimal use of each of the software packages, to study in detail any discrepancies between the solvers, and to assess the remaining simulation challenges. The study clearly highlights the importance of understanding EM simulation principles and their inherent limitations.

A planar monopole UWB antenna with switchable band-rejection feature

An Ultra-Wideband (UWB) planar monopole antenna with a switchable band-notched response is presented. In order to achieve a band-rejection, a U-shaped slot is embedded in the radiating patch. The operation of the U-shaped slot is controlled by a PIN diode. Measurement and simulation results revealed a minor effect of the lumped components loading on the radiation pattern of the antenna. The main emphasis of the work has gone into simplification and validation of the presented switchable band-notching technique, which has a potential for further antenna miniaturization using RF MEMS technology.

Analysis of Composite Textiles Filled with Arbitrarily Oriented Conducting Fibres Using a Periodic Model for Crossed Strips

Composite textiles formed by regular fibres in combination with conducting fibres are analysed by using a model for a periodic array of crossed strips. Through comparison with measurements it is demonstrated that this simple model can provide a good first estimation of the shielding effectiveness for this kind of innovating materials

Modelling of shielding effectiveness using small samples of tested materials

The limitations of a widely used setup consisting of two horn antennas for evaluation of shielding effectiveness is investigated. The proposed method can provide a non-destructive characterization of small bulk materials and grid structures with sizes comparable to the wavelength of the scanning signal. As it is proved by the numerical modeling the suggested measurement setup inevitably introduces some spurious diffraction. Nevertheless, the use of statistical approximation allows effectively retrieving the shielding effectiveness of studied samples, which is validated by the analytical results.