Gigantic Coaxial Line for Experimental Studies of the Interaction of Nanosecond Electromagnetic Pulses with an Ionized Gas Medium

A large-scale coaxial line filled with the plasma of RF discharge has been developed for laboratory modeling of the effects of the interaction of ultrashort electromagnetic pulses (EMPs) with the atmosphere and the ionosphere in the KROT facility. The oversized coaxial line ensures pulse transmission through an ionized medium in the TEM mode, which corresponds to the polarization of the transverse electromagnetic wave in free space, and in uniform isotropic plasma. The coaxial line has a length of 10 m and a diameter of 140 cm. The processes of propagation of the nanosecond and subnanosecond pulses in this line, in vacuum and with plasma, have been simulated numerically.

Design of SWB Antenna with Triple Band Notch Characteristics for Multipurpose Wireless Applications

A compact concentric structured monopole antenna for super wide band (SWB) applications with triple notch band characteristics is designed and experimentally validated. The antenna covers an immense impedance bandwidth (1.6–47.5 GHz) with sharp triple notch bands at 1.8–2.2 GHz, 4–7.2 GHz, and 9.8–10.4 GHz to eliminate interference from co-existing advanced wireless services (AWS), C bands, and X bands, respectively. By loading an E-shaped stub connected at the top of the patch and by etching a split elliptical slot at the lower end of the radiating patch, the band rejection characteristics from 1.8–2.2 GHz for the AWS and 4–7.2 GHz for the C band are achieved, respectively. Further, by making use of a C-shaped resonator near the feed line, band rejection from 9.8–10.4 GHz for the X band is obtained. By varying the parameters of the antenna, the notch bands are controlled independently over a wide range of frequencies. The antenna provides good radiation characteristics, constant group delay response, and better gain over the pass band. The experimental results indicate that the designed antenna offers a remarkable reduction in gain and high variation in group delay over the stop bands. To characterize the wideband property and linear phase response of the designed antenna, its time-domain performance is extensively described and evaluated, which assure pulse transmission with minimum distortion.