Konrad Godziszewski

New Interference Technique for Determination of Low Loss Material Permittivity in the Extremely High Frequency Range

In this paper a new interference technique for material permittivity determination in the extremely high frequency range using a vector network analyzer is described. The novelty of this technique is the absence of a reference interference channel and there is no need to rotate the experimental sample that simplifies the measurement process and increases its accuracy. In order to approve this technique, the respective experimental setup was designed. The setup structure and theoretical background of interference fringe minimum formation were described. Based on the quasi-optical principle of the setup operation, the formula for the calculation of the material permittivity was derived. Two different dielectric materials were subjected to test measurements using the created experimental setup. Obtained average values of permittivity in the 50÷70 GHz range are ε = 10.67 ± 0.09 and ε = 2.35 ± 0.03 for sapphire and optical glass, respectively. For the purposes of result verification, the time-domain processing technique was also applied to calculate the permittivity of these materials. Besides, the obtained data are compared with those reported in the literature.

Accuracy enhancement of material characterization in sub-THz range

In this paper many aspects of material characterization in sub-THz frequency range are shown. Methods of reducing unwanted reflections from construction of the measurement setup and from the sample under test are proposed. The influence of lens tilt on electromagnetic field distribution in location of the sample is investigated.

Emerging ferroelectric ceramic-polymer composites for sub-THz tunable devices

The paper presents the recent research in ferroelectric ceramic-polymer composites for sub-THz tunable devices. Developed composites are very promising group of materials due to the possibility of fabrication of materials with desired electrical and mechanical properties. Appropriate selection of components for ceramic slurry enables to obtain composites with low losses and high tunability. Using tape-casting technology and water-dispersible polymers environmentally friendly thin and flexible ferroelectric tapes can be realized. Particular emphasis is made on measurement methods of electrical properties in sub-THz range. In addition, various composites, process of fabrication and characterization of developed ferroelectric ceramic-polymer composites are discussed.

Radio-over-fiber link for WLAN and LTE systems

The paper presents the results of Investigation of a radio-over-fiber transmission link suitable for LTE or IEEE 802.11b/g systems. Remote Antenna Unit is completed by a low-noise microwave amplifier for improving sensitivity of receiver. The measurement results show that the inclusion of an amplifier in the RAU is a low-cost and reasonable solution.

Investigation of influence of measurement conditions on accuracy of material characterization in sub-THz frequency range

In this paper results of investigations of the influence of measurement conditions on the accuracy of material characterization in sub-THz range were presented. Different fabrication issues as well as metrological aspects were taken into account. Studies were focused on LTCC materials as emerging technology that can be used in developing of multilayer sub-terahertz devices. Simulation and experimental studies showed that appropriate preparation of measurement setup and samples under test are key elements to achieve high measurement accuracy.

The ink-jet printing of microstrip lines on ferroelectric ceramic-polymer composites and its characterization in sub-THz range

In this paper the application of the ink-jet printing technology to microstrip line fabrication on tunable ferroelectric ceramic-polymer composites for devices operating at sub-terahertz range have been presented. Measurement results shown that the designed material is usable for creating structures able to tune some their electromagnetic characteristics. Relatively low temperature technology process (ink-jet printing technology) is able to deposit conductive lines on the ceramic polymer. The ink-jet printed silver microstrip lines can operate at sub-terahertz range.

Terahertz frequency-domain instrumentation for vector characterization of composite materials

In this paper the introduction to the sub-THz technologies is presented. Many aspects of the sub-THz measurement techniques are reviewed and compared. A unique laboratory of Institute of Radioelectronics at Warsaw University of Technology equipped with the VNA with Frequency Extenders up to 500 GHz is demonstrated.

Investigations of tunability of ferroelectric ceramic-polymer composites

In this paper results of investigations of ferroelectric ceramic-polymer composites for tunable sub-THz devices are presented. Influence of a polymeric binder and type of ferroelectric powder on tunability is studied. Setup for tunability measurements is also described. Measurement results are shown and compared. Obtained results are very promising and suggest that developed composite materials can be an alternative to currently used state-of-the-art tunable materials operated at sub-THz frequency band.