V. E. Lyubchenko

Synchronization and combining of the radiation powers of active microwave antennas integrated with field-effect transistors

Combining of the powers of microwave generators designed as a array of log-periodic antennas on a dielectric substrate and field-effect transistors as active components is experimentally investigated. Possibilities of a substantial increase in the generation efficiency due to mutual synchronization of radiators are demonstrated, and conditions for formation of the radiation pattern are studied.

Generation of microwave oscillations in a log-periodic antenna integrated with a field-effect transistor

Generation of microwave oscillations in a hybrid integrated circuit comprising a field-effect transistor and a log-periodic microstrip antenna on a dielectric substrate is experimentally investigated. Generation is observed at both the fundamental harmonic and higher frequencies corresponding to the antenna resonances in the frequency band 6–60 GHz. Possibilities of optimizing the generator design are studied in application to operation in centimeter and millimeter wave bands.

Ultra Wideband Wireless Communication on the Base of Noise Technology

The process of ultra wideband (UWB) data transmission on the base of noise continuous waveforms is considered. The new method of code spectral modulation is proposed for data insertion onto noise continuous carrier. The spectral compression of received ultra wideband waveforms is performed by means of double spectral processing. Experimental results of quadrature correlation measurements in 3.1-4.1 GHz frequency range with successive selection of transmitting data are discussed.

Thermomechanical strains in small-size Au-GaAs thin film structures

Abstract In small-size contact technology, when dielectric covers with opened circular windows are used, the thermal strains appear to be considerable because of the different thermal expansion of the semiconductor (GaAs), deposited metal (Au) and dielectric cover (SiO 2 ), widely used for manufacturing the devices. The strains occurring in the Au layer, in turn, result in defect formation or disappearance. It depends on two contrary processes: (i) the Au atom migration from the Au layer on the SiO 2 surface to the GaAs windows at temperatures below 450°C; (ii) the Ga atom migration from the GaAs windows into the Au on SiO 2 at temperatures beyond 450°C. Therefore, these processes ought to be taken into account in the pattern design of “honey-comb” structures: window dimensions, distances between the windows, SiO 2 and Au layer thicknesses and their ratio.

Generation of microwave radiation by active antennas with field-effect transistors in a quasi-optical resonator

Effects of locking of generator antennas (GAs) with field-effect transistors by the electromagnetic field formed as a result of reflection of radiation from a semitransparent dielectric mirror are analyzed. The possibility of spatial combining of the radiation powers of the GAs placed on a common dielectric substrate and forming a linear or a 2D matrix is demonstrated. It is shown that application of a reflecting mirror can substantially expand the GA mutual locking band and abandon external locking for power combining in the 2D matrix.

Generation of microwave radiation by active antennas with field-effect transistors locked by an external signal

Effects of locking by an external electromagnetic field of an array of oscillator antennas (OAs) designed by field-effect transistors integrated with log-periodic antennas are analyzed. The possibility of spatial combining of the radiation powers of OAs placed on a common dielectric substrate and arranged into a 1D array is demonstrated. It is shown that application of external locking can ensure severalfold broadening of the locking band of an ensemble of independent self-oscillators as compared to the case of mutual locking by a common field propagating in the dielectric substrate.

Active log-periodic antennas for spatial and quasi-optical microwave power combining

Power combining in the array of microwave oscillators, consisted of log-periodical antennas with field-effect transistors as active elements, is experimentally studied. The opportunity for considerable improvement of oscillation efficiency due to the mutual synchronization is shown and conditions of formation of the radiation pattern are defined.

Millimeter Wave Propagation in GaAs and Si Two-Layer Dielectric Rod Waveguides

Traveling wave mode transformation in GaAs and Si dielectric rod waveguides at frequencies 75 -110 GHz is experimentally studied. The influence of p-n and i-n junction capacitance is noticed as a varactor type component ,that imposes new applications of two layer structures in millimeter wave integrated circuits.

Solar Blind MSM-Photodetectors Based on Al x Ga 1-x N/GaN Heterostructures Grown by MOCVD

The MOCVD technology of semiconductor heterostructures for ultraviolet photodetectors was developed. Solar blind AlGaN/GaN MSM photodetectors were fabricated and investigated. Directly on the MSM-diode we have measured a Schottky barrier height of 1.1 eV for Ni and 1.4 eV for Mo contacts on AlGaN. Effect of different buffer layers on the detector performances has been demonstrated. Detectors exhibit low dark currents and high sensitivity within the range of 250 - 290 nm. Effect of high optical excitation level on detector performance is discussed.

Microstrip antenna–generator based on gallium arsenide

A design of the microstrip antenna with an epitaxial structure used as a dielectric substrate is developed. The epitaxial structure contains a thin layer of n-type gallium arsenide of on a GaAs semi-insulating substrate. The layer thickness is selected with consideration for the carrier depletion region that appears at the interface between the metal layer, which forms the antenna, and the doped semiconductor layer. We demonstrated experimentally the possibility of application of this design as a FET antenna–generator in a frequency range of 10–15 GHz.