Yevhen Yashchyshyn

Rigorous analysis and investigations of the scan antennas on a ferroelectric substrate

In this paper, the radiation characteristics of a new microstrip electrically controllable scan antenna are investigated theoretically and experimentally. Both longitudinal and transverse currents are taken into account. The substrate of this antenna consists of a ceramic-polymer composite with modified ferroelectric powder Ba0,65 Sr0,35TiO3 and an appropriate polymer. The permittivity of the substrate can be varied by an applied electric control dc-bias field. It allows to change electrically phase constant of the propagation wave and, in turn, changes the main beam direction. It is shown that the main beam position changes over 30deg when dc-bias field is applied up to 200 V. The comparison with experimental results has fully confirmed the usefulness of the scan-antenna concept and method of analysis. Presented results of the electrical scanned antenna investigation are promising for various fixed-frequency applications where frequency scanning is impossible

Local Positioning for Wireless Sensor Networks

This workshop paper gives an overview of local positioning and tracking principles for wireless sensor networks including recent results of the European project RESOLUTION (reconfigurable systems for mobile local communication and positioning). Measurements of a first demonstrator applying a frequency modulated continuous wave (FMCW) radar principle are presented. The unlicensed ISM band around 5.8 GHz, 150 MHz bandwidth and less than 25 mW effective isotropic radiated transmit power are used. Excellent 3-D positioning accuracies in the order of 4 cm in an anechoic chamber and 18 cm in a conference hall with strong multipath and area of 800 m2 are measured. Furthermore, the results of optimized radio frequency integrated circuits and a suitable compact flash card are outlined.

Voltage-controlled ferroelectric microstrip antenna for phased arrays

A new concept of microstrip antenna for phased arrays is proposed using a voltage-controlled ferroelectric thin tape in the multilayered structure. This paper presents the ferroelectric thin tape, its theoretical analysis and design. The results indicate that this concept has many advantages, is very practical and promising. It gives possibilities of several applications, e.g. in phased arrays and smart antennas.

Development and Investigation of an Antenna System With Reconfigurable Aperture

The concept and results of investigation of a waveguide slot antenna with reconfigurable aperture is presented. Solutions are based on the utilized semiconductor material, which allows one to design the electronically reconfigurable antennas. The key element of the reconfigurable antenna is a surface PIN (SPIN) diode whose conductivity changes proportionally to the plasma density. SPIN structures can be activated selectively and cause, in turn, the generation of the desired shapes of radiation pattern. It allows one to extend the function possibilities of waveguide slot antennas compared with the conventional one.

The leaky-wave antenna with ferroelectric substrate

The leaky-wave antenna is investigated using the 3D FDTD method. The structure analyzed is a ferroelectric dielectric waveguide on the ground plate. The top of the ferroelectric material is covered with a conducting sheet with slots. It is shown that this antenna may have further advantages of smaller thickness, simpler beam-steering control and lower cost.

Rigorous analysis and investigations of the scan antenna on ferroelectric substrate

In this paper the radiation characteristics of new microstrip electrically controllable scan antenna are investigated, theoretically and experimentally. Both longitudinal and transverse current are taken into account. The substrate of this antenna consists of ceramic-polymer composite with modified ferroelectric powder Ba/sub 0.65/Sr/sub 0.35/TiO/sub 3/ and appropriate polymer. It shows that the beam angle changes are over 30/spl deg/ when DC bias field is applied up to 200 V.

Time-Modulated Reconfigurable Antenna Based on Integrated S-PIN Diodes for mm-Wave Communication Systems

This paper concerns the study of the mm-wave reconfigurable antennas based on S-PIN diodes suitable for using in mm-wave communication systems. The investigated antennas were designed, fabricated, and subjected to the measurements in both steady and transient states. One selected antenna was incorporated into a wireless system to determine its suitability for operating in such a system as a time-modulated linear array. By means of appropriate switching of the antenna, multiple radio frequency (RF) chains were simulated in a receiver having only one RF chain. This allowed applying a combining technique for improving the system performance in a presence of a strong interfering signal.

Null pattern synthesis of ferroelectric smart antennas

In this paper, new method of null pattern synthesis of antenna arrays without phase shifters and attenuators has been presented. This concept is based on utilizing a voltage-controlled ferroelectric array, where the variable pattern of each antenna element is used to synthesize the array pattern with desired nulls.

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.

Extending Functionalities of Waveguide Slot Antennas by Means of Reconfigurable Aperture

The concept and results of investigation of some waveguide slot antenna with reconfigurable aperture have been presented in this paper. Discussed solutions have been based on the utilized semiconductor material. It allows to design the electronically reconfigurable antennas. The key element of the reconfigurable antenna is a surface PIN (SPIN) diode whose conductivity changes proportionally to the plasma density. SPIN structures can be activated selectively and cause, in turn, a generation of the desired shapes of radiation pattern. It allows to extend function possibilities of waveguide slot antennas compared with conventional one.