Radiation of ultra-wideband electromagnetic pulses by pulsed excitation of rectangular antenna

Levitas³

et al. 2014

Pulsed excitation of small size monopole antennas for generating wideband electromagnetic pulses was used. The monopoles were excited by electrical pulses having rise times of 600 ps, 200 ps, 70 ps and voltages 100 V, 15 V, and 0.4 V respectively. Antennas spanning (0.3-26) GHz bandwidth, including broadband horns with coaxial outputs, were employed to receive signals, which were investigated using (0-26) GHz passband sampling oscilloscope. It was found that waveforms of signals, received by the antennas, mostly depend on the pulse rise time and on the details of geometry of monopoles. The electromagnetic pulses have relatively long duration of about 30 ns and spectral harmonics up to 22 GHz. Therefore they can be attributed to pulses with large base. The results show that the upper frequencies of the spectrum most probably are cut off by existing arrangement. Usage of such pulses can find wide practical application when they are received after transmission trough different media by a number of antennas having different operational frequency ranges, followed by digital signal processing.

Section: Discussionmentioning

confidence: 99%

“…Investigation of EM pulses radiated by plane rectangular, monopole antennas was carried out in work [4]. Short pulses with sub nanosecond rise time were used for pulsed excitation of the antennas.…”

Section: Introduction *mentioning

confidence: 99%

Receiving and Detection of Ultra-Wideband Microwave Signals Radiated by Pulsed Excitation of Monopole Antennas

Levitas³

et al. 2014

“…On the other hand frequencies above 4 GHz were not used because of existence of linear-like decrease of the power density up to 16 GHz. It is known that the plot maximum of the spectral density of power can be shifted and also correction of the plot non-uniformities can be regulated, both by coating on the surface of antenna thin resistive or nanometric thin metallic films [11].…”

Section: Analysis Of Thementioning

confidence: 99%

Reflecting and Polarizing Properties of Conductive Fabrics in Ultra-High Frequency Range

Matuzas

et al. 2015

The system based on ultra-wide band (UWB) signals was employed for qualitative estimation of attenuating, reflecting and polarizing properties of conductive fabrics, capable to prevent local static charge accumulation. Pulsed excitation of triangle monopole antenna of 6.5 cm height by rectangular electric pulses induced radiation of UWB signals with spectral density of power having maximum in ultra-high frequency (UHF) range. The same antenna was used for the radiated signal receiving. Filters and amplifiers of different passband were employed to divide UHF range into subranges of 0.3-0.55 GHz, 0.55-1 GHz, 1-2 GHz and 2-4 GHz bands. The free space method, when conductive fabric samples of 50 x 50 cm 2 were placed between transmitting and receiving antennas, was used to imitate a practical application. Received wideband signals corresponding to the defined range were detected by unbiased detectors. The fabrics made of two types of warps, containing different threads with conductive yarns, were investigated. It was estimated attenuation and reflective properties of the fabrics when electric field is collinear or perpendicular to thread direction. In the UHF range it was revealed good reflecting properties of the fabrics containing metallic component in the threads. The system has advantages but not without a certain shortcoming. Adapting it for specific tasks should lead to more effective usage, including yet unused properties of the UWB signals.

“…belong to the narrow band, condition 0.01 <  < 0.25 is attributed to the wide band, and the signals with 0.25   < 1 belong to the UWB signals [5].…”

Section: Introductionmentioning

confidence: 99%

Microwave radiation imaging using inverse synthetic aperture radar technique

Levitas

et al. 2015

ElAEE

Double-ridged horn antennas were used in ultra wideband radar system to create microwave radiation images. The images were obtained using inverse synthetic aperture radar technique. Transfer function of the calibrated radar system was close to one up to 22 GHz. High quality images of metallic and organic objects were created due to unique characteristic of ultra wideband radiated pulse. Metallic objects covered by visually opaque obstacles became detectable. The components of measurement setup and the data processing are both important for the formation of these images. The obtained results confirmed the ability of ultra wideband radar to form images for various practical applications including security systems. Higher frequency of such radar system can be raised up to 40 GHz-50 GHz.