Experimental investigation of three-layer electromagnetically coupled circular microstrip antennas

The broadband behaviour of a three-layer electromagnetically coupled circular microstrip antenna is investigated experimentally. The effects of interlayer spacings and the thickness of the parasitic layers on the impedance bandwidth, 3 dB beamwidth and pattern shape, are studied. Experiments show that this structure can provide a frequency bandwidth as high as 20% with a low crosspolarisation level and a moderately high gain.

Peeking through the Iron Curtain: Memories of Watching Finnish Television in Estonia during Soviet Occupation

The present study analyses the memories of watching Finnish television in Estonia during the last decades of the Soviet occupation from the late 1960s until the beginning of 1990s. The study stems from a culturalist approach, perceiving television as a relevant aspect in the audiences’ everyday lives. It explores the significance of Finnish television on the society of occupied Estonia from the point of view of its historical audiences. The literature review concentrates on concepts such as the power of television, transnational media, historical audience reception and memory as an object of research. It also explains the concept of spillover, which refers to the unintentional bilateral flow of television signals from one country to another. Despite the numerous efforts of the Soviet authorities to prevent the viewing of the "bourgeois television", there still remained a small gap in the Iron Curtain. The study describes the phenomenon of watching Finnish television in Estonia. It provides understanding about the significance of watching Finnish television in Soviet Estonia through the experiences of its former audience. In addition, it explores what do people remember about watching Finnish television, and why. The empirical data was acquired from peoples’ personal memories through the analysis of private interviews and written responses during the period from February 2010 to February 2011. A total of 85 responses (5 interviews and 83 written responses) were analysed. The research employed the methods of oral history and memory studies. The main theoretical sources of the study include the works of Mati Graf and Heikki Roiko-Jokela, Hagi Šein, Sonia Livingstone, Janet Staiger and Emily Keightley. The study concludes that besides fulfilling the role of an entertainer and an informer, Finnish television enabled its Estonian audiences to gain entry into the imaginary world. Access to this imaginary world was so important, that the viewers engaged in illegal activities and gained special skills, whereby a phenomenon of "television tourism" developed. Most of the memories about Finnish television are vivid and similar. The latter indicates both the reliability and the collectiveness of such memories, which in return give shape to collective identities. Thus, for the Estonian viewers, the experience of watching Finnish television during the Soviet occupation has became part of their identity.

A geodesic constant method for computing high-frequency mutual coupling between antennas on general quadric cylinders

A Geodesic Constant Method (GCM) is outlined which provides a common approach to ray tracing on quadric cylinders in general, and yields all the surface ray-geometric parameters required in the UTD mutual coupling analysis of conformal antenna arrays in the closed form. The approach permits the incorporation of a shaping parameter which permits the modeling of quadric cylindrical surfaces of desired sharpness/flatness with a common set of equations. The mutual admittance between the slots on a general parabolic cylinder is obtained as an illustration of the applicability of the GCM.

Quasi-Orthogonal Design and Performance Analysis of Amplify-And-Forward Relay Networks with Multiple-Antennas

This paper is on the design and performance analysis of practical distributed space-time codes for wireless relay networks with multiple antennas terminals. The amplify-andforward scheme is used in a way that each relay transmits a scaled version of the linear combination of the received symbols. We propose distributed generalized quasi-orthogonal space-time codes which are distributed among the source antennas and relays, and valid for any number of relays. Assuming M-PSK and M-QAM signals, we derive a formula for the symbol error probability of the investigated scheme over Rayleigh fading channels. For sufficiently large SNR, this paper derives closed-form average SER expression. The simplicity of the asymptotic results provides valuable insights into the performance of cooperative networks and suggests means of optimizing them. Our analytical results have been confirmed by simulation results, using full-rate full-diversity distributed codes.

Multi-Port Network Approach for the Analysis of Dual Band Fractal Microstrip Antennas

The multiport network approach is extended to analyze the behavior of microstrip fractal antennas. The capacitively fedmicrostrip square ring antenna has the side opposite to the feed arm replaced with a fractal Minkowski geometry. Dual frequency operation is achieved by suitably choosing the indentation of this fractal geometry. The width of the two sides adjacent to this is increased to further control the resonant characteristics and the ratio of the two resonance frequencies of this antenna. The impedance matrix for the multiport network model of this antenna is simplified exploiting self-similarity of the geometry with greater accuracy and reduced analysis time. Experimentally validated results confirm utility of the approach in analyzing the input characteristics of similar multi-frequency fractal microstrip antennas with other fractal geometries.

Studies on Ultra Wideband Triangular Patch Antennas for Imaging Applications

This paper presents simulation and experimental studies on the characterization of ultra wideband antennas for imaging applications. Various configurations of antennas were simulated for their time and frequency domain characteristics with special emphasis on flat responses for group delay and gain versus frequency. Parametric studies reported here showed that locating the capacitive feed strip near the vertex of the triangle gave better response in these respects. An antenna with operating frequency from 2.9GHz to 4.1GHz was fabricated and measured.