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

Abstract

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.

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

“…Problems of wideband signal detection were broached in paper [6]. The detection depends on available input power and in our case this value depends on amplification of UWB signal.…”

“…High voltage electrical pulse is generated by a pulse generator, rise time of about 1 ns and amplitude during investigations being 230 -250 V (see plot a). This pulse excites the transmit antenna resulting in ultra-wideband pulse generation [6]. The radiated large B signal (see plot b), is passing through the conductive fabrics and is received by the receive antenna.…”

“…One of the examples is reconfiguration of antennas either mechanically or electronically for example using diodes to change current distribution or effective antennas geometry [5]. In paper [6] it was proposed method for generating UWB EM pulses using pulsed excitation of small size antennas by short high voltage electrical pulses. The radiated electromagnetic pulses have spectral harmonics above 22 GHz, but relatively long duration, about 20 -25 ns.…”