Piotr Słobodzian

Influence of firing process quality on dielectric constant of microwave LTCC substrates

Purpose – The purpose of this paper was to investigate the influence of non-uniform temperature distribution inside a box furnace during the firing process on electrical properties of the low-temperature co-fired ceramic (LTCC) materials used in radio frequency (RF)/microwave applications. Design/methodology/approach – The authors studied the change in dielectric constant of two popular LTCC materials (DP 951 and DP 9K7) depending on the position of their samples inside the box furnace. Before firing of the samples, temperature distribution inside the box furnace was determined. The dielectric constant was measured using the method of two microstrip lines. Findings – The findings showed that non-uniform temperature distribution with spatial difference of 6°C can result in 3-4 per cent change of the dielectric constant. It was also found that dielectric constant of the two tested materials shows disparate behavior under the same temperature distribution inside the box furnace. Practical implications – The ...

The Application of Macromodels to the Analysis of a Dielectric Resonator Antenna Excited by a Cavity Backed Slot

The analysis of cavity backed, slot excited dielectric resonator antennas (DRA) is accelerated with the use of a macromodel within the framework of the IE-MoM formulation. The macromodel can be regarded as a projection of complete information about the DRA onto the slot in a wide frequency range, and thus it provides huge reduction in the total number of unknowns. Consequently, this enables a considerable decrease in computation time and makes it possible to curry out fast optimization of a feeding network structure enclosed in a cavity without the need for handling large systems of linear equations associated with the DRA.

Slot Excited Dielectric Resonator Antenna Above a Cavity - Analysis and Experiment

The integral equation -method of moments approach to analyzing a cavity backed, slot excited dielectric resonator antenna is validated experimentally (by measurements). First, the closed rectangular metal box is considered to validate the cavity treatment. Then, the whole DRA structure, i.e. the cavity along with the slot and dielectric resonator, is tested to prove definitively correctness of the approach used.

Estimation of the repeater gain required for a wireless link

The question of repeater application arises very frequently in contemporary wireless and cellular communication systems. The paper is intended to show a basic methodology that allows us to estate the gain of antennas used in an active or passive repeater involved in a wireless link. Some key equations governing a link budget of the wireless link with repeaters are briefly described and the influence of the link range, its geometry and attenuation of the dominant obstacle on the repeater gain is discussed. The question concerning the use of passive repeaters is also addressed.

Microfluidical Microwave Reactor for Synthesis of Gold Nanoparticles

Microwave treatment can reduce the time of selected syntheses, for instance of gold nanoparticles (AuNPs), from several hours to a few minutes. We propose a microfluidic structure for enhancing the rate of chemical reactions using microwave energy. This reactor is designed to control microwave energy with much higher accuracy than in standard devices. Thanks to this, the influence of microwave irradiation on the rate of chemical reactions can be investigated. The reactor consists of a transmission line surrounded by ground metallization. In order to deliver microwave energy to the fluid under test efficiently, matching networks are used and optimized by means of numerical methods. The monolithic device is fabricated in the low temperature co-fired ceramics (LTCC) technology. This material exhibits excellent microwave performance and is resistant to many chemical substances as well as high temperatures. Fabrication of the devices is described in detail. Measurements of microwave parameters are performed and differences between simulation and experiment results are discussed. Finally, the usefulness of the proposed device is proved in exemplary synthesis.

A LTCC microwave-microfluidic reactor

This paper describes a prototype of a LTCC microwave-microfluidic reactor, which was built to test a possibility of accelerating chemical reactions. The authors put their focus on conditions that must be met to assure reliable assessment of power that is delivered to the reactor, and which is used to stimulate a chemical reaction.

Challenges of design and practical application of LTCC chip antennas

In this paper key challenges related to design, manufacturing and practical application of small LTCC antennas are described and discussed. A summary of the state of the art in LTCC antenna technology is presented and then the focus is put on limitations that have to be taken into account in the course of antenna design and manufacturing. Finally, some aspects related to practical application of LTCC antennas are discussed.

The SIE-MoM analysis of mixed vertical-horizontal metallization inside uniform waveguides and cavities

This paper describes application of the Surface Integral Equation (SIE) approach to the analysis of scattering by metal structures inside uniform waveguides and cavities. The metal structures consist of a number of mixed vertical-horizontal rectangular strips. The formulation of SIE uses the full dyadic electric waveguide Green function, and the integral equation is solved by means of the Method of Moments (MoM). In our work we show a methodology for validation of this formulation. We also demonstrate effectiveness of this formulation by comparing the results of our calculations with solutions obtained by means of commercially available software, which is based on the Finite Integration Technique (FIT). The comparison shows that our approach is more effective both in terms of computer resources and time of calculations.

Improvement of the frequency bandwidth of LTCC meander antenna

The paper describes the study of possibility to improve the bandwidth of the LTCC (Low Temperature Cofired Ceramics) antennas. It is well-known that bandwidth broadening of microstrip antennas can be achieved by substrate structurizing. In our paper we describe the influence of an air cavity beneath a radiating patch or strip on the LTCC antenna performance. Results of computer simulations using HFSS™ software are shown. Then, manufacturing process is described. Results of measurement of network parameters and radiaton patterns of the antenna model are presented. Finally, a comparison between measured parameters and computer simulations is discussed.

A comparison of two practical methods for measurement of the dielectric constant of LTCC substrates

This paper describes a comparison of two methods that are used in practice to determine the dielectric constant of RF and microwave substrates, namely the method of two microstrip lines (the microstrip differential phase method) and SPDR (split post dielectric resonator) method. We compare accuracy of these two methods that is subject mainly to geometry measurements. Our case study, based on an LTCC (low temperature co-fired ceramic) material with high relative permittivity (εr=16), shows that the method of two microstrip lines has potential to give almost identical results to those from the SPDR method. Our approach, however, requires several samples to be measured, and the obtained results exhibit quite large standard deviation. In addition to this the approach is very sensitive to the quality of samples under test.