Vol 69, No 3 (2024)

Infinite ultra-wideband (UWB) arrays of TEM horns and Vivaldi antennas were considered. At the first stage we used an array model in the quasi-periodic excitation mode in the form of a Floquet channel. It was implemented in the HFSS electromagnetic modeling system. At the second stage the array parameters in the cluster excitation mode were determined using the calculated scattering matrix of the Floquet channel. Two clusters of TEM horns and Vivaldi antennas were analyzed. They were finite along one coordinate and infinite along the other. It was investigated how the cluster size, frequency, amplitude distribution of exciting waves, scanning in the sector of angles affect the shape of the amplitude-phase distribution of the field in the array aperture. It was shown that the field distribution in the emitting aperture may differ significantly from the distribution of exciting waves at the inputs of the array elements. An explanation of this effect based on the representation of the field in the array in the form of a superposition of its eigen waves was proposed.

A discharge of limited length (“plasma column”) in a gas-discharge tube filled with a rarefied gas was studied. The discharge is created due to the one-sided excitation of an extended high-frequency discharge supported by a propagating azimuthally symmetric mode of the surface wave. It is shown that a “plasma column” can be an effective plasma antenna at operating frequencies below the plasma frequency (ω_p), with frequency tuning due to changes in the length of the “plasma column”.

The modeling of echo signals from distributed radar objects taking into account the noise of their angular coordinates is considered. Relationships are presented that allow the transition from a multipoint model of an arbitrary object containing tens, hundreds and even thousands of emitting points to a model composed of four emitting points located at the vertices of a square. As an example, we synthesized an airplane model containing only four points. It is obtained on the basis of a multipoint model composed of 56 points. Using numerical modeling methods, it has been shown that angular noise generated by multi-point and four-point aircraft models have identical correlation functions and similar parameters of the probability density distribution of angular coordinate noise. The obtained result is also confirmed by semi-natural modeling methods using a matrix simulator.

The ASMD-FSMD method for designing digital devices is considered, which consists of constructing a block diagram of an algorithmic state machine with a data path (ASMD), which describes the behavior of the device, and creating project code in Verilog in the form of a finite state machine with a data processing path. (finite state machine with datapath – FSMD). One of the directions for the development of the ASMD-FSMD methodology is the use of features of the hardware description language (HDL). A hypothesis has been put forward: in the ASMD-FSMD technique, it is possible to apply several non-blocking assignment operators to the same variable in one synchronization cycle, which will lead to an increase in device performance. The hypothesis put forward was investigated in the design of synchronous multipliers that implement the classical multiplication algorithms c and d. Experimental studies have confirmed the validity of the put forward hypothesis, while the speed of the multipliers increases two to three times, and the cost of implementation in most cases decreases compared to the traditional approach.

Based on previously conducted measurements of the tunneling current-voltage characteristics of metal-SiO₂-Si (MOS) structures, modeling of the insulating potential in an ultra-thin (4.2 nm) silicon oxide film was performed. The potential in the dielectric was defined in the shape of a trapezoid, with the lateral slopes simulating transition layers and the top base representing the bulk of SiO₂. The model parameters – the barrier height and the coordinates of the trapezoid's corner points – were calculated to achieve the maximum match between the experimental and theoretical voltage derivatives of the current logarithm. Common features of the insulating potential, similar to those in thinner silicon oxide films (3.7 nm), were identified: the barrier occupies up to half of the nominal volume of the dielectric gap and is shifted towards the gate electrode, with its slope towards the semiconductor substrate being much more gradual compared to the slope adjacent to the gate.

Using a set of standard exact solutions described by ordinary differential equations and elementary functions, geometrized models of plane electron beams in l-, and W-representations were studied. A comparison is made of the capabilities of the geometrized approach and the paraxial theory.

A generalized technique for analyzing a current-controlled passive frequency mixer circuit using guard intervals between adjacent heterodyne signal pulses is proposed. The results of calculations and simulations in the Micro-Cap environment are presented for two cases of mixer input impedance: RLC circuit, RC circuit. The dependences of the modulus of the transfer impedance of the mixer for various durations of protective intervals are considered.