Andrey Generalov

Dielectric Rod Waveguide Antenna as THz Emitter for Photomixing Devices

We propose a dielectric rod waveguide antenna (DRW) integrated with a photomixer as a THz emitter. This represents a different approach as opposed to the classical solution of a substrate lens. Main goals are an inexpensive alternative to substrate lenses, reduction of both reflections on the semiconductor-air interface and scattering of terahertz-generated power into the substrate. A radiation pattern measured at 137 GHz is shown as a proof-of-concept. In order to increase radiated power, the improvement of the rod antenna is discussed. Finally, as an application example, evanescent coupling of the DRW into a high index whispering gallery mode resonator is shown.

Wide Band mm- and Sub-mm-Wave Dielectric Rod Waveguide Antenna

The design of a dielectric rod waveguide (DRW) antenna for frequencies of 75-325 GHz is presented. The optimal broadband antenna geometry is determined using numerical simulations . A single DRW antenna is matched with metal waveguides of different sizes for different frequency bands. Measurement results agree very well with the simulation results up to 325 GHz; the gain of the antenna stays nearly constant ( G ≈ 10 dB) over the whole frequency range measured from 75 to 325 GHz (160% relative bandwidth). The upper limit is due to our limited manufacturing capability to produce sharp antenna tips. The return loss of the antenna is better than 15 dB. The radiation patterns are nearly independent of frequency. The 3 dB beamwidth is 50 °-60 °, and the 10 dB beamwidth is about 95 °. This indicates that the aperture size of this end-fire antenna decreases as a function of frequency, and this observation agrees well with the earlier observation that the phase center of a DRW antenna moves towards the antenna tip as a function of frequency. Also the cross polarization was studied. The cross-polarization level is better than -15 dB at all frequencies .

Millimeter-Wave Power Sensor Based on Silicon Rod Waveguide

This paper presents a novel type of RF power sensor, based on a metallic structure integrated into an mm-wave range dielectric rod waveguide made of Si. The metallic structure is employed as a bolometer. Numerical simulations of temperature distribution are shown. A prototype was tested at frequencies of 45 GHz-1 THz and a power levels from 0.1 to 500 mW. The power sensor showed the sensitivity of 0.51 Ω/mW resistance change.

Carbon nanotube network varactor

Microelectromechanical system (MEMS) varactors based on a freestanding layer of single-walled carbon nanotube (SWCNT) films were designed, fabricated and tested. The freestanding SWCNT film was employed as a movable upper patch in the parallel plate capacitor of the MEMS. The measurements of the SWCNT varactors show very high tunability, nearly 100%, of the capacitance with a low actuation voltage of 10 V. The functionality of the varactor is improved by implementing a flexible nanocellulose aerogel filling.

Reconfigurable mm-wave phase shifter based on high impedance surface with carbon nanotube membrane MEMS

A novel phase shifter based on high impedance surface (HIS) with carbon nanotube (CNT) membrane MEMS is proposed. The CNT MEMS HIS is integrated into a dielectric rod waveguide (DRW) so that the CNT membrane acts as a movable ground plane. We present a novel fabrication method of the phase shifter being significantly simpler than those previously used. The device performance is verified through numerical simulations that show a theoretical phase shift of 260° with a 7 volt bias applied. So far we have experimentally demonstrated a CNT membrane varactor, where the distance of the CNT membrane and metal patches changed from 2 μm to 0.4 μm with a 10 volt bias.

Beam-steering antennas at millimeter wavelengths

In many emerging applications of millimeter waves, electronic focusing and beam steering is needed. We present a survey of mm-wave beam steering antennas, where the necessary phase change for antenna elements is achieved using various electronically tuneable elements, e.g. microelectromechanical systems (MEMS), such as tuneable leaky-wave antennas, shaped lens antennas with integrated switched feed array, active reflectarray, tuneable high-impedance surface, and dielectric rod waveguides with integrated phase shifters. Some early results of our own relevant investigations are also presented.

Antennas for electronic beam steering and focusing at millimeter wavelengths

This paper discusses the prospects of millimeter-wave beam steering antennas, such as tuneable high-impedance surface, dielectric rod waveguide with an integrated phase shifter, tuneable leaky-wave antenna, active reflectarray, and shaped lens antenna with an integrated switched feed array. In these antennas the necessary phase change for antenna elements can be achieved using various electronically tuneable elements, but in our case MEMS are used. Some early results of our investigations are presented.