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Offset Dual Cylindrical Reflector Antenna

The design of a dual offset cylindrical antenna at Ku band is described here. The reflectors unlike in a conventional dual offset are singly curved (parabolic in one direction and flat in orthogonal direction). The offset parabolic profile of the subreflector can be seen in Figure 1. The projected aperture of the main reflector can be seen in Figure 2. It is possible to round off the corners of the reflector without much performance degradation. The configuration of the antenna where each reflector focuses in orthogonal planes can be seen in Figure 3. The focusing optics only works perfectly in the plane of symmetry so the efficiency of the antenna is only about 55%. However the antenna is capable of producing elliptical beams and may be constructed from sheet metal.

Predicted far-field patterns at 11.2 GHz in elevation and azimuthal are shown in Figure 4 and Figure 5.

Figure 1

FIGURE 1: Side view of the cylindrical reflectors.

Figure 2

FIGURE 2: Projected apertures in the boresight direction.

Figure 3

FIGURE 3: Angled view of the antenna configuration.

Figure 4

FIGURE 4: Predicted far-field elevation pattern at 11.2 GHz.

Figure 5

FIGURE 5: Predicted far-field azimuthal pattern at 11.2 GHz.

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