Transient field calculation of aperture antennas

Abstract

The method of transient field calculation for large aperture antennas is proposed. It is shown that in the time domain, the calculation of the transient field is relatively simple for all points in the half-space in front of the aperture. The basic properties of the transient field are discussed.Index Terms-Aperture antennas, broad-band antennas, transient analysis.

Fresnel's Formulas in Time Domain

“…In a pure conducting medium, where , the first term in (9) is absent and only the second one represents the resolvent. In this case the dissipative terms in (11) become simpler in the vicinity of the influence sphere, (12) It is evident that the terms, which are proportional to the second power of the conductivity, do not depend on distance at all. When the sphere expands, , the dependence of such a term on the dissipation becomes more complex (13) and the decrease of this term with time as a power law appears.…”

Pulsed field of a rectangular plane aperture

“…For the actual antennas with a finite operating frequency band, the near-and far-field features are determined by the time derivative of the impulse response. In the case of a circular aperture, the derivative of the impulse response consists of two time-shifted different-polarity pulses [5]. In the case of a rectangular aperture, the derivative of the transient characteristics consists of one positive pulse, which has the largest amplitude and is determined by the leading edge of the pulsed transient characteristic, and several timeshifted negative-polarity pulses determined by the trailing edge of the impulse response and having relatively small amplitudes.…”

“…With allowance for the latter assumption, the pulse oscillogram at a point can be represented in the form [5] S e (t, r)…”

“…However, the number of works devoted to calculating the pulsed fields of the more complex-shaped apertures is limited [9]. This work deals with calculating the pulsed fields of plane rectangular apertures, briefly describes a method for calculating the plane-aperture pulsed field, shown in [5], presents the expressions obtained for the field of the plane rectangular aperture in the near zone inside and outside the floodlight beam, and discusses the pulsed-field features.…”

“…Aperture antennas allowing us to create a plane wave within the limits of a floodlight beam of the aperture at small distances from the latter hold a special place among the pulsed antennas. Tens of papers are aimed at describing the fields of a circular plane aperture [3][4][5] and a parabolic antenna with a circular aperture [6][7][8]. However, the number of works devoted to calculating the pulsed fields of the more complex-shaped apertures is limited [9].…”