Vasilii Semkin

Beam Switching Conformal Antenna Array for mm-Wave Communications

In this letter, the design and measurement results of a millimeter-wave beam switching antenna are presented. Several antenna prototypes have been fabricated and measured in planar and conformal installations. The developed prototype consists of three antenna arrays of 16 patch elements in each array and it is operating at 61 GHz with linear polarization. A single-pole three-throw semiconductor switch is attached to the manufactured prototype using copper pillar attachment. The main beam direction of the convex antenna can be changed by switching between the antenna arrays in the prototype. Half sphere 3-D radiation pattern measurements have been performed. For the convex prototype, bent on the cylinder with radius 25 mm, beam switching with -32° / + 34° degrees is achieved.

Studies on E-band antennas and propagation

We have studied beam-steering radio in the E-band., e.g. for high-capacity communication links. Lens antennas provide high gain and are suitable for integration at millimeter wave frequencies, e.g., for beam-switching a planar antenna array with a switching network may be integrated to the surface of the lens; one patch is activated at a time for each beam direction. In order to improve the scanning characteristics and reduce reflection losses, we have studied optimization of the lens shape using ray tracing. A propagation channel model has been developed for point-to-point links in street canyons and from roof to street in an urban environment. The model is based on extensive measurements in the E-band. The substance of the channel model is in identification of multipath components in the environment. That is supported by separate measurements of radio wave reflection and scattering from various environmental structures such as building walls.

Characterization of Radio Links at 60 GHz Using Simple Geometrical and Highly Accurate 3-D Models

In order to effectively deploy high data rate millimeter-wave communication systems in urban environments, accurate information about the radio-wave propagation channel is essential. Radio-wave propagation in urban scenarios strongly depends on the topography of the immediate surroundings. A measurement campaign has been carried out to evaluate the impact of propagation effects on the radio channel at the rooftop level of buildings. In the simulation part of the paper, we present two 3-D models produced with different techniques: first, a simple geometrical model and, second, a highly accurate close-range photogrammetry model; the latter replicates the detailed building geometry. To construct a highly accurate 3-D model, images obtained by an unmanned aerial vehicle were utilized together with the photogrammetry technique. In this paper, we provide a thorough comparison between the measured and the simulated power delay profiles by conducting shooting-and-bouncing ray-based simulations for the rooftop scenario using two 3-D models of different accuracy. The results show that the use of the close-range photogrammetry model can provide better propagation prediction at millimeter-wave frequencies.

Suitability of roll-to-roll reverse offset printing for mass production of millimeter-wave antennas: Progress report

In this work, we investigate different printing technologies suitable for mass production of millimeter-wave antennas and other devices, e.g., holograms and frequency selective absorbers, on flexible substrates. We concentrate especially on roll-to-roll reverse offset printing. The driving factors are low cost, high accuracy, high efficiency, and reliable performance. Therefore, we need to find and characterize suitable flexible substrates (permittivity and loss tangent at mm-wavelengths), conducting inks (viscosity, surface resistance of the resulting conducting layer), adhesion of the ink to the substrate, and feature size capable for printing mm-wave antennas and other passive devices in high volumes.

Characterization of inkjet patch antenna on different ground planes at millimeter-wave frequencies

In this paper we present simulation and measurement results of a patch antenna, working at mm-wave frequencies, printed with inkjet technology on a flexible polyethelene naphtalate (PEN) substrate. Different ground planes are investigated due to the reason that antenna can be placed on different objects with different materials. Antenna was placed first on a copper tape, then on silver painted styrofoam and finally the PEN substrate was back-painted with silver. Matching properties and radiation performance are examined. Disposition the antenna structure on the ground plane allows achieving higher values of realized gain. Maximum realized gain value of 7.2 dB is measured from the patch antenna placed on the painted styrofoam.

Towards printed millimeter-wave components: Material characterization

This paper presents the results from evaluation of suitable materials and ink properties for printing millimeter wave components. Dielectric parameters (relative permittivity and loss tangent) of various potential substrate materials are extracted from S-parameter measurements and simulations. Test samples have been printed over Polyethylene Terephthalate (PET) and Polyethylene Naphthalate (PEN) substrates and the measurement of the ink properties have been carried out.

Millimeter wave antenna array based on dielectric-filled waveguides

This paper presents components based on metallic dielectric-filled waveguides (DFWG) for antenna arrays. Air-filled waveguide feeding networks have low losses but the spacing between the elements of the array cannot be half-a-wavelength which is required for the grating lobe free radiation patterns. By filling the waveguides with dielectric material, the physical dimensions can be decreased. Three prototypes are developed for the lower E-band (71–76 GHz): a transition from DFWG to the standard WR-12 waveguide, a single antenna element based on the DFWG, and a 1×4 linear antenna array. The prototypes are manufactured and measured. The measured insertion loss of the structure with two transitions is 1.3–2 dB at the desired frequency range. The measured realised gain for the single element is 7–9 dBi at the desired band.