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Ultrawideband (UWB) systems have attracted great attention in recent years with their potential to support the large data bandwidths of modern media streams. To meet these needs, early UWB antenna designs have been rediscovered and improved upon, and a new generation of UWB antenna designs is emerging. This talk will present a historical introduction to UWB antennas. The importance of learning the...
The main physical phenomenon caused by periodicity is Bragg reflection. It results in the opening of the forbidden gap in the spectrum of the periodic structure. The Bragg reflection occurs both in the case of unbounded periodic medium as well as in a case of a bounded periodic structure like a periodic waveguide. However, in the waveguide geometry dispersions become more complex due to their folding...
A new multi-band microstrip patch antenna element with three folded shaped slots and two coaxial feeds is presented. The designed antenna covers frequency bands ranging from GPS (1.575 GHz) to WLAN, 5.8 GHz and new DSRC, 5.9 GHz. The antenna design has been optimized to provide desired performance in GPS (1.575) GHZ, GPRS (1.85 GHz), WLAN (2.4 GHz), WLAN (5.8 GHz), and DSRC (5.9 GHz). The antenna...
Dielectric loaded waveguide filters are extremely attractive for space applications, thanks to the reduction of size and weight that can be achieved using these components. Another remarkable advantage is the high temperature stability and the high quality factor of the recent dielectric materials, allowing in many cases these products to be the optimum choice for the filter realisation in comparison...
The micro machined horn antenna is a high-efficiency antenna suitable for applications in millimeter-wave imaging systems, remote-sensing, and radio astronomy. A novel design of micro machined horn antenna is presented. Horn excited with a quasi-Yagi antenna. In this paper micromachining process of this antenna, and simulation results of a horn structure operate around 330 GHz using Agilent High Frequency...
In this paper we present a procedure for designing microwave bandpass filters with a single pair of attenuation poles at finite frequencies. The filter topology consists of pentagonal open-loop resonators where the couplings between nonadjacent resonators are responsible for the attenuation poles at finite frequencies. The coupling coefficients between the open-loop resonators are determined using...
Since the pioneering works of Brillouin and Sommerfeld [1], the intriguing concept of group velocity has generated a lot of academic excitement. In particular, many papers, both theoretical and experimental, have reported superluminal group velocity and have explained this phenomenon in the context of Einstein's relativity [2]-[7]. In general in these papers, superluminal group velocity is associated...
Surface wave launchers have been used to feed leaky wave antennae. We present here for the first time measured results of a two element CPW-fed surface wave launcher array. It was shown at 22 GHz that this array can beam steer the surface wave ±20°. Array fabrication, measurement set-up and signal processing will also be described in the paper.
The development of low-loss, low-cost, and stable passive waveguide devices has been a major focus of research in the past few decades. Several techniques have been proposed in which direct laser writing is one of the more appealing methods since complex photolithography may no longer be required. These techniques are based on the creation of a core region by laser-induced refractive index change...
In this paper, the design and measurement of the requirement standards of the IEC610004-21, over a compact electromagnetic reverberation chamber are presented. Although the immunity tests may be made in an anechoic chamber, it's more laborious, takes a longer operation time, needs a high power amplifier and present a high cost experiment. On the other hand, a reverberation chamber is presented as...
The waveform of the electric field radiated by an antenna in a UWB system is usually a distorted form of the input pulse applied at the terminals. This distortion can be expressed in terms of the antenna impulse response in the time domain or directional transfer function in the frequency domain. Even for a simplest antenna like a linear dipole, the impulse response can be direction dependent. However,...
In this paper we present a procedure for designing microwave bandpass filters with a single pair of attenuation poles at finite frequencies. The filter topology consists of pentagonal open-loop resonators where the couplings between nonadjacent resonators are responsible for the attenuation poles at finite frequencies. The coupling coefficients between the open-loop resonators are determined using...
In this paper the classical boundary value approach employing the separation of variable technique is used to analyze the properties of elliptic dielectric resonators. In this approach, the fields inside the resonator are expanded in terms of Mathieu and modified Mathieu functions. Numerical results are given for resonant frequencies of different modes as well for field distributions inside the resonator.
A new phase shifter using Substrate Integrated Waveguide (SIW) scheme combined with a post-based technique is presented. Phase shifting is achieved by changing the diameter and the position of inductive posts inserted in the SIW substrate. Simulations were carried out using one post, and two posts. Results have shown a good agreement with the theory. To prove the concept, prototypes have been fabricated...
In this paper, a model for the analysis of a non-uniform multi-conductor transmission-line (MTL) system consisting of a bundle of twisted-wire pairs (TWPs) in the presence of electromagnetic interference (EMI) is presented. The objective of such a model is to analyze the susceptibility of TWP bundles to EMI in digital subscriber line (DSL) communication systems. In the past, crosstalk noise in TWP...
This paper addresses a two-dimensional inverse scattering numerical technique for microwave imaging for breast cancer detection. We present an accurate and efficient way to obtain the location, shapes, and dielectric properties of malignant tumors inside the body. The accuracy of the reconstructed image is achieved because the dispersion properties and spatial heterogeneous characteristics of the...
It has been previously demonstrated in optical fiber that superimposed chirped gratings can be used to implement multi-frequency transmission filters. In this paper, we propose an equivalent electrical implementation of this structure for use in microstrip technology. In an analogous fashion to an optical fiber grating, we modulate the strip-width of a 50-ohm microstrip according to the sum of two...
Statistical models, often calibrated by measurements offer a straightforward way to characterize a wireless channel transfer function and associated effects such as signal fading and multi-path propagation [1]. On the other hand, site-specific models, estimate channel transfer functions taking into account the important effect of such parameters as material and geometric properties of the channel...
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