Persons

• Counter: 537 | Comments : 0

The one-dimensional waveguide photonic structure - the photonic crystal with the controlled frequency characteristics - has been implemented. The tuning of the center frequency of the low-loss transmission window of the photonic crystal was achieved by selecting the parameters of irregularity I in the photonic crystal, while the control of the transmission value at selected frequency was performed by changing voltage on Pin-diode. The possibility of implementing the microwave device in the X-band with the pass band of 70 MHz at the 3 dB-level and with the transmission coefficient adjustable in the band from 1.5 dB to 25 dB with changing the voltage on PIN-diode from 0 to 700 mV, based on the waveguide photonic crystal, has been shown.

• Counter: 1337 | Comments : 0

The computer simulation and experimental investigation of the frequency dependencies of the reflectance and transmittance of photon crystals based on the microstrip lines in the 0–20 GHz frequency band have been performed. The investigations were conducted for the photon crystal with the irregularity, introduced as the changed geometry size of the stripline conductor or changed substrate permittivity of one of the sequence microstrip sections. A good agreement between the calculations and the experimental results has been obtained. The possibility for application of open microwave transmission lines for realizing the parameters measurement method of the material, which acts as irregularity in photon crystal, has been demonstrated.

• Counter: 331 | Comments : 0

The electrophysical properties of composites based on epoxy adhesive with inclusions in the form of the carbon nanotubes, fine particles of graphite and ferrite microparticles in the frequency range from 0.1 to 6 GHz have been investigated. The influence of the ferrite inclusions spatial location in the composite volume on the frequency dependences of the transmission coefficients of microstrip photonic crystals, containing the composite samples with the ferrite inclusions, has been shown. It has been stated that the values of the transmission and the reflection coefficients in the window of photonic crystal transparency are determined by the spatial location of the ordered ferrite inclusions (ferrite wires) with respect to the direction of the electromagnetic wave electric vector and its propagation direction in the photonic crystal. It has been determined that with the induction increase of the orienting magnetic field, occurring in the process of curing the composite, containing the ferrite particles, the decrease of the distances between ordered locations of the ferrite inclusions (ferrite wires) is observed.

• Counter: 1019 | Comments : 0

The possibility of determination of thickness and electro-physical parameters of thin nanometer and sub-micrometer dielectric and metal films in the sandwich-like structures, using the results of measurements on the reflection and transmission spectra of optical and microwave radiation, has been shown. The measurement results for the refractive index of SnO films in the thickness range from 40 nm to 2,8 µm, and the conductivity of cuprum films applied to the glass substrates have been presented.

• Counter: 1153 | Comments : 0

The most important units of the frequency formers are the frequency multipliers. The possibility of creating a microwave high multiplicity frequency multiplier with the built-in microwave switch on n - i - p - i - n -diode has been considered. For allocating the multiplied signal from spectrum the output multisecion bandpass filter in the form of a sequentially counter stud microstrip resonators, tuned to the required 24 harmonic, has been used. The highest switch off effect is achieved when the n - i - p - i - n -diode is turned on so that one n -region of the diode has been galvanically coupled to the input element of the microstrip filter, the other n -region has been connected to the first stud resonator of the bandpass filter. When n - i - p - i - n -diodes are simultaneously switched to the first and central resonators of the band-pass filter, the total relative change of the output signal exceeds 70 dB under the bias voltage changing on each of the n - i - p - i - n -diodes from 0 to 1.7 V.

• Counter: 2210 | Comments : 0

The method of the multiparameter measurements of characteristics of semiconductor structures: the electrical conductivity of the n-layer, which acts as a substrate of the semiconductor structure, the thickness and conductivity of the highly doped epitaxial n-layer, has been proposed. The method is based on using the one-dimensional microwave photonic crystal with the periodicity defect, which contains the investigated semiconductor structure. The characteristics, measured by this method, of epitaxial arsenide-gallium structures, consisting of the epitaxial layer and semi-isolating substrate, have been presented.

• Counter: 1467 | Comments : 0

The impact of continuous midrange power microwave fields on the characteristics of the square-wave RC -generator with the multi-channel buffer circuit and matching circuit, formed on the 74HC14 series inverters with the built-in Schmitt trigger, has been investigated. It has been shown that the increasing power of electromagnetic radiation reduces the pulse width and, hence, increases the frequency of the RC -generator output signal. The RC -generator output signal sensitivity to the impact of the microwave signal is decreased with an increase of both, the supply voltage and the microwave signal power. It has been concluded that the output characteristics of the digital radioelectronic systems are the most susceptible to the impact of the microwave signal while using the semiconductor integrated circuits, which are part of these systems, as the active elements and while choosing the operation modes of DC voltage circuits, significantly different from nominal ones.

• Counter: 1405 | Comments : 0