We investigate here a number of variations of the Para-IRA, which is an Impulse Radiating Antenna configured for parachute delivery. We consider first two scale models of the Para-IRA with aluminum reflectors, and then we consider a full-scale version built from fabric. In the scale models, we first investigate the effect of using a large F/D ratio in an IRA. We then investigate the effect of u...

A multiplexed Cassegrain reflector antenna with a 2 × 2 open-ended rectangular waveguide (OERW) matrix feed and an orbital angular momentum (OAM) mode mux is proposed for the simultaneous generation of three OAM modes (l = 0, ±1). The OAM mode mux (OMM) was designed using sequential combinations of quadrature hybrids, crossovers, and phase shifters to multiplex and demultiplex three OAM modes a...

This paper is concerned with the design of a new type of multi-purpose deployable membrane reflector. The reflector structure consists of a central expandable hub, a number of thin-walled foldable ribs connected radially to the hub, and a precision-shaped membrane supported and tensioned by the ribs. This concept is known as a collapsible rib-tensioned surface reflector. A methodology for the d...

The radiation of a circular cylindrical reflector antenna in the presence of imperfect flat earth is treated in an accurate manner. The boundary value problem is formulated in terms of a full-wave integral equation converted to the dual-series equations and then regularized by using analytical inversion of the static part. The resulting Fredholm second-kind matrix equation is solved numerically...

Dual-Band Reflectarrays Using Microstrip Ring Elements and Their Applications with Various Feeding Arrangements. (August 2006) Chul Min Han, B.S., Korea University Chair of Advisory Committee: Dr. Kai Chang In recent years there has been a growing demand for reduced mass, small launch volume, and, at the same time, high-gain large-aperture antenna systems in modern space-borne applications. Thi...

We consider the problem of recovering a reflecting surface such that for a given point source of light the directions of the reflected rays cover a prescribed region of a far field sphere and the density of the distribution of the reflected rays is a function prescribed in advance, where the aperture of the incident ray cone is also prescribed in advance. Mathematically this problem requires on...

T his is the first of two articles describing a number of time domain solver 3D EM field simulations of an antenna feed consisting of a circular waveg-uide with a septum polar-izer and two external coaxial connector ports. Measurements of the actual S-parameters of a constructed feed were then compared to the simulations, to determine which mesh and solver settings afforded good accuracy withou...

The use of dual polarization in meteorological radars offers significant advantages over single polarization. Recently a standard single-polarization C-band radar was upgraded to operate in dualpolarization mode. The antenna has a 4.2m diameter parabolic reflector with a prime-focus feed. A spherical Fresnel-zone holographic technique was used to obtain the radiation pattern for the upgraded an...

In this paper, a planar directional beam-switchable antenna with four orthogonal beam directions is proposed. The proposed antenna is designed with two crossed active elements and two parasitic elements for each direction. The design methodology is described on the basis of the Yagi-Uda method for the active and parasitic elements, respectively. By adjusting the effective electric lengths of th...