Focal waveforms for various source waveforms driving a prolate‐spheroidal impulse radiating antenna (IRA)

Abstract

[1] Impulse radiating antennas (IRAs) are designed to radiate very fast pulses in a narrow beam with low dispersion and high field amplitude. For this reason they have been used in a variety of applications. IRAs have been developed for use in the transient far-field region using parabolic reflectors. However, in this paper we focus in the near field region and develop the field waveform at the second focus of a prolate-spheroidal IRA. Certain skin cancers can be killed by the application of a high-amplitude electric field pulse. This can be accomplished by either inserting electrodes near the skin cancer or by applying fast, high-electric field pulses without direct contact. We investigate a new manifestation of an IRA, in which we use a prolate spheroid as a reflector instead of a parabolic reflector and focus in the near-field region instead of the far-field region. This technique minimizes skin damage associated with inserting electrodes near the tumor. Analytical and experimental behaviors for the focal waveforms of two and four-feed arm prolate-spheroidal IRAs are explored. With appropriate choice of the driving waveform we maximize the impulse field at the second focus. The focal waveform of a prolatespheroidal IRA has been explained theoretically and verified experimentally.Citation: Altunc, S., C. E. Baum, C. G. Christodoulou, E. Schamiloglu, and C. J. Buchenauer (2008), Focal waveforms for various source waveforms driving a prolate-spheroidal impulse radiating antenna (IRA), Radio Sci., 43, RS4S13,

Simulation study of delivery of subnanosecond pulses to biological tissues with an impulse radiating antenna

“…These two conditions led us to use an inhomogeneous, partially lossy dielectric lens. In a previous paper, Altunc et al [] demonstrated that a multilayer dielectric lens can be used to match the impedance from air to tissue. The lens consists of five layers of different dielectric materials with dielectric constants varying in an exponential profile from air to the innermost layer, ϵ rmax .…”

“…While ns pulses are delivered with electrodes [Silve et al, ], delivering ultrashort electrical pulses with antennas to biological targets becomes attractive in reaching deep targets. One such antenna is an impulse radiating antenna that relies on a prolate spheroidal reflector [Baum, ; Altunc et al, ; Kumar et al, ]. At the first focus of this reflector, a transverse electromagnetic (TEM) wave launcher projects the EM waves to the reflector; from there they are redirected into the second focus.…”

A Subnanosecond Pulsed Electric Field System for Studying Cells Electropermeabilization

“…Two possible solutions were suggested theoretically by Carl Baum, as part of a major research effort undertook by the Frank Reidy Research Center for Bioelectrics at Old Dominion University (USA): an impulse radiating antenna (IRA) operated in air [12], [13], in combination with a complex many layer dielectric lens [14] and another prolatespheroidal reflector, operated underwater [15]. More recently, at the same research center, a dielectric rod antenna was also suggested as a candidate for generating subnanosecond PEFs for the stimulation of neurological tissue [16].…”