A nanosecond microwave pulse source based on a nonlinear transmission line (NLTL) with saturated ferrite, operating in the S-band, has been developed and experimentally tested. Its key feature is the absence of electromagnets in its design. The source consists of a sharpening NLTL with an unsaturated ferrite, a corrugated NLTL, a coaxial high-pass filter, and a combined antenna. Both the sharpening and corrugated lines utilize NiZn ferrite rings. NdFeB permanent magnets are used to saturate the ferrite in the corrugated NLTL. The line provides efficient generation of high-frequency pulses in the frequency range of 2.7–3.6 GHz. The operating voltage range of the source is 50–190 kV. The coaxial high-pass filter has a passband of 1.2–4 GHz, which allows for effective radiation of oscillations excited in the line as well as the high-frequency energy concentrated on the front of the voltage pulse. The combined antenna has an operating range of 1–4 GHz. A pulsed periodic operating mode was implemented with a pulse repetition rate of 50 Hz up to 2000 pulses per burst. At an operating voltage of 170 kV, the central frequency of the radiated pulse is 3.4 GHz. The effective potential of the source is 65 kV.

A process for modifying a 3D UWB combined antenna based on an analysis of its characteristic modes is presented. This begins with an investigation of the characteristic modes properties of the combined antenna's main components, followed by the characteristic modes properties of the antenna as a whole, with the goal of developing a concept for effectively widening its operating bandwidth. To do this, the key attributes of characteristic mode theory are analyzed in the frequency domain–the frequency dependences of characteristic angles and modal significances and the distributions of characteristic currents for these modes are visualized. This allowed us to obtain valuable information on the contribution of the most significant characteristic modes to the antenna's radiated power and, based on a thorough analysis of the mode current distributions in the vicinity of the antenna's feed input, propose a productive principle for widening its operating frequency band. This principle was embodied in the design of an experimental model of a modified combined UWB antenna. The results of full-wave modeling of the antenna model and measurements of its parameters and characteristics are in good agreement. The antenna operating frequency range at VSWR < 2 is 0.5 – 2.75 GHz. The modified antenna has a higher gain than the original antenna across virtually the entire operating frequency band. Its greatest increase is observed in the range from 1.9 to 2.8 GHz. The effective radiation potential rEp of the modified antenna is 9 % (in the experiment) and 11 % (in full-wave modeling) higher than the corresponding value for the original combined antenna.

The effective area of a receiving antenna in the form of the open end of a standard waveguide was measured in a numerical and real experiment using two different reference antennas. The receiving antenna is designed to register powerful microwave pulses. The influence of the phase center position of the transmitting antenna was taken into account during measurements of the receiving antenna effective area in the frequency band of 8–12 GHz. The possibility of reducing the effective area of the antenna at its constant value in the frequency band by optimizing the size of the diaphragms installed in the input window of the waveguide is investigated.

A high-power source of ultrawideband radiation with elliptical polarization based on a 64-element array of spiral antennas was developed. The array was excited by a bipolar voltage pulse with an amplitude of up to 240 kV and a duration of 1 ns at a repetition rate of 100 Hz. Radiation pulses with an ellipticity coefficient of 0.64 and a peak field strength of 250 kV/m at a distance of 10 m were obtained.

The effect of a thin-walled polyethylene container on the radiation characteristics of a combined antenna has been investigated. The antenna is designed to radiate ultra-wideband pulses of nanosecond duration. The possibility of increasing the E field amplitude in the radiated ultra-wideband pulse by optimizing the container has been investigated.

The paper studies the influence of the voltage pulse waveform exciting the UWB antenna, on the radiated E-field amplitude. It is shown that the radiated pulse amplitude of the combined antenna excited by bipolar voltage pulses, is higher than that excited by monopolar voltage pulses.

A cylindrical equidistant helix antenna has been created. The helix geometry of the antenna determined its central frequency of the operating band, equal to 1 GHz. This frequency corresponds to the maximum spectra of a bipolar voltage pulse with duration of 1 ns. Helixes identical to those of a single antenna were used in horizontal four-element linear arrays. Antenna arrays with different periods of d were studied in the axial mode with simultaneous excitation of elements by a bipolar voltage pulse of 1 ns duration and in the mode of scanning at a fixed angle in the horizontal plane. Experimental measurements were carried out in the frequency and time domains.

Results of a simulation and experimental study of a combined ultra-wideband antenna, which is a combination of electric and magnetic dipoles, are presented. The input signal recovery of the transceiver path of combined antennas made by the MathCad code and the experimental one were compared. The reconstruction took place according to the frequency and phase responses of the transceiver path of these antennas.

Comparative experimental investigations of combined and helical ultra-wideband antennas are performed. The antennas are optimized to be excited by the 1 ns bipolar voltage pulses. The antenna matching with the feeder is studied in the frequency domain. The antenna patterns by the peak value of the radiated field are studied in the time domain for E- and H-planes. The effective potential values in the boresight radiation direction are studied as well with the same exciting voltage pulse at the antenna inputs. A probability is found for the effective potential of the helical antenna to be larger than that of the combined antenna in the case of an arbitrary orientation of the receiving linearly-polarized antenna. The effective potential of both antennas was registered in the pattern maxima at the same distances. This probability is equal to 0.6.

Ultrawideband elliptically polarized radiation is numerically and experimentally studied. The analysis is performed for the axial radiation of a cylindrical helical antenna that is excited by a bipolar voltage pulse with a duration of 2 ns. The results are used for construction of a source of high-power ultrawideband pulses with elliptical polarization. The radiation pulses with an effective potential of 300 kV are generated at an amplitude of the bipolar voltage pulse of 200 kV and a repetition rate of 100 Hz.

The results of optimization of the geometry of a combined ultrawideband antenna excited by a 1-ns bipolar pulse are presented. Numerical and physical experiments have been performed to optimize the increase in the electric-field strength in the direction of the antenna main beam. It has been shown that the peak field strength can be increased by 6%.

Here, we describe a source of high-power ultrawideband radiation with elliptical polarization. The source consisting of a monopolar pulse generator, a bipolar pulse former, and a helical antenna placed into a radioparent container may be used in tests for electromagnetic compatibility. In the source, the helical antenna with the number of turns N = 4 is excited with a high-voltage bipolar pulse. Preliminary, we examined helical antennas at a low-voltage source aiming to select an optimal N and to estimate a radiation center position and boundary of a far-field zone. Finally, characteristics of the source in the operating mode at a pulse repetition rate of 100 Hz are presented in the paper as well. Energy efficiency of the antenna is 0.75 at the axial ratio equal to 1.3. The effective potential of radiation of the source at the voltage amplitudes of the bipolar pulse generator equal to -175/+200 kV reaches 280 kV.

A pulsed source of the ultrawideband radiation based on a nonlinear line and a single combined antenna is proposed. The frequency that corresponds to the maximum radiation spectrum can be tuned in the interval 0.5–1.3 GHz. The effective radiation potential of the source is 95–310 kV.

A source of high-power nanosecond ultrawideband electromagnetic pulses is described. The 3-ns-long bipolar voltage pulse with a 90-kV amplitude is applied to the input of four-element antenna array. The effective radiation potential values E p R = 560 kV were obtained at a 100-Hz pulse repetition rate.

A wire model and a combined antenna for radiation of low-power bipolar pulses with a duration of 200 ps, which is based on this model, are developed. The frequency-domain characteristics of the model and the time- and frequency-domain characteristics of the combined antenna are studied. Linear antenna arrays based on the developed combined antenna are designed and the radiation characteristics of these antennas in the wave-beam scanning mode are analyzed.

The generation and emission of high-power ultrabroadband electromagnetic pulses are studied. The possibility of high-voltage (about 100 kV) bipolar voltage pulses with a duration of about 200 ps is demonstrated. The electromagnetic pulses with a FWHM of less than 100 ps, an effective potential of up to 400 kV, and a repetition rate of 100 Hz are generated using the 16-element antenna array.

Ultrawideband combined antennas optimized to radiate 0.2-ns length high-voltage (~100 kV) and low-voltage bipolar pulses have been developed. Linear arrays of low-voltage antennas were investigated in the mode of wide-angle steering by a wave beam.

The properties of the discharge in and radiation from an open gas-filled diode to which high-voltage nanosecond pulses are applied from the RADAN-220 generator are studied. Electromagnetic radiation in the X-ray, UV, visible, and near-IR ranges of the spectrum, as well as high-power subnanosecond (0.5-to 0.7-ns-long) pulses of ultra-wide-band (UWB) electromagnetic radiation, are recorded when a diffuse discharge is initiated in atmospheric pressure air. For the coaxial cathode and anode, the open gas diode emits radially polarized UWB pulses, whereas for the cathode in the form of a segment, the UWB radiation is linearly polarized. The effective potential for both designs of the diode is ER = 6 kV. It is shown that the plasma in the discharge gap serves as a source of soft X rays and the metallic anode generates hard X rays.

The paper presents the analysis of factors influencing antenna frequency bandwidth. The ways of widening antennas bandwidth into lowand highfrequency ranges are shown. Design and characteristics of three combined ultrawideband antennas are described.