George Lojewski

Aperture Couplings in Multilayer Filtering Structures

In multilayer structures apertures in metallic sheets can be used as coupling elements between resonators located on different layers, allowing very compact filter designs. In this paper, some novel types of planar microwave bandpass filters, using aperture couplings, in structures with three metallic layers, are considered. Couplings between two miniaturized resonators are investigated, by full electromagnetic field simulation. Based on the results of this study, several models of planar microwave bandpass filters, with a single or with two apertures, are designed, verified by simulation, fabricated and measured. Compared to the classical filters, these novel structures show a good compactness and can offer some technological advantages.

Backward couplers using coupled composite right/left-handed transmission lines

A new asymmetric backward coupler is obtained by edge-coupling two types of composite right/left handed (CRLH) lines. This novel coupler is analyzed in a microwave range (1–10 GHz) and the magnitude of the scattering parameters reveals tight coupling effects (even 0 dB) in a dual frequency band and also very good directivity in the working band.

Electromagnetic field evaluation on an antennas shared site

The last two decades have seen a strong technological development in the area of wireless voice and data transmission, thus adding new sources of electromagnetic fields in the urban environment besides existing FM radio and TV broadcasting. There are situations in which one site is used by multiple technologies emitting in different frequency bands and with different powers. The paper presents the results and methodology employed in measuring and evaluating electromagnetic field exposure on a building rooftop, where TV and FM radio broadcast stations coexist with GSM, IS-95, UMTS and WiMAX base stations, microwave links and different data communication technologies.

Investigation on microwave signal propagation through some left-handed structures

Some aspects of microwave propagation through left-handed materials are investigated in this paper. The strong distortion of a Gaussian TEM pulse through a material with negative refraction index is studied in the time domain. Moreover, a method of extracting the constitutive parameters of a material by using the scattering parameters of a sample two-port is developed. This method is then applied to some left-handed microstrip structures.

Compact Microwave Bandpass Filter using Multilayer Resonator-Embedded Packaging

The design of a compact microwave multilayer bandpass filter with aperture couplings and with an embedded-resonator topology is shown and investigated in this paper. Different types of inter-resonator and resonator-feedline couplings, in a three metallic-layer configuration, are presented. The bandpass filter is designed using coupling coefficients extracted through a full-wave electromagnetic-field simulation. The proposed multilayer configuration demonstrates a significant size reduction (about 50% in surface area), compared to a classical microstrip filter. The designed filters were realized in both classical electro-chemical and mechanical engraving technologies, in order to verify the influence of the manufacturing process on the filter characteristics. The measured parameters of the experimental models demonstrate the validity of the design method, based on electromagnetic-field simulation.

Broadband Planar Filters with Enhanced Couplings Using Defected Ground Structures

In this paper a study of some microwave microstrip bandpass filters (BPF) using defected ground structures (DOS) is presented. This technique allows designs of tight couplings without the necessity of using very narrow coupling gaps. Based on the results of the study, four-pole cross-coupled planar microwave bandpass filters were designed, with a single or with two ground slots. Compared to similar microstrip filters without defected ground, the simulated performances of these novel structures indicate some technological advantages

Compact Wireless Devices with Defected-Ground Structures

In this paper are presented some investigations on micro- strip defected ground structures (DGS). It is shown that the presence of a slot in the ground plane can substantially enhance the electric coupling, or the electric part of a mixed coupling between resonators and its external feedings. The proposed technique can eliminate the very narrow coupling gaps needed for a tight coupling and thus can relax the fab rication tolerances.

Couplings Control in the Defected Ground Star-Geometry Dual-Mode Filter

Investigations on coupling coefficients in a star-geometry filter with defected ground are presented in this paper. The device is compact, requiring a surface area of more than 6 times smaller than the area needed for a conventional patch dual mode resonator

Novel microwave band-pass filter with dual-mode triangular resonators

Microstrip filters with dual-mode triangular resonators having two transmissions zeros, one on each side of the passband, are investigated. The investigation refers to the physical understanding of the behavior of a triangular loop resonator. The effects of varying different parameters of this filter structure were studied. Some filters of this type were designed and tested by simulation. An experimental model of such a filter has been measured. Simulation and measurement results are in good agreement.

Eyes on transient and harmonic balance analyses for high speed design

With the ever increasing complexity of the high speed digital and analog design both time and frequency analyses are to be considered. The present paper presents a brief overview on linear and nonlinear simulations type and evaluation of the effects of choosing transient or harmonic balance in evaluation of interconnections on a printed circuit board by using eye diagram tool.