Coplanar Conical Plates in a Uniform Dielectric Lens with Matching Conical Plates for Feeding a Paraboloidal Reflector
One form of an impulse radiating antenna (IRA) consists of a paraboloidal reflector fed by conical transmission lines that propagate a spherical TEM wave, which originates from the focal point of the reflector. A diagram which depicts such an IRA is shown schematically in Figure 1. The design considerations of a uniform dielectric lens useful in launching a spherical TEM wave onto such a paraboloidal reflector have been investigated in earlier work1, 2, 3, and the geometrical parameters for the lens design are indicated in Figure 2. The lens design in essence consists of specifying certain parameters. These include the cylindrical radius, h, of the outermost ray which intercepts the reflector, the relative permittivity ε r of the lens medium, and the angle, θ r (out), from the apex of the conical transmission line (focal point) to the edge of the reflector. This angle is determined by the reflector geometry through the ratio F/D, where F is the focal distance from the center of the reflector and D is the reflector diameter. We also need to specify the angle θ r (in) made by the line inside the lens with respect to the directions of launch.
KeywordsCharacteristic Impedance Spherical Wave Reflector Geometry Lens Design Lens Region
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