| 摘要 |
A two-band multimode microwave source for an antenna of a low-elevation-tracking radar comprises a higher-frequency section nested in a lower-frequency section, the two sections having E-planes perpendicular to each other. The lower-frequency section includes two outer pairs of waveguides separated by a block which convergingly projects beyond their output ends and is bisected by the E-plane of that section. The higher-frequency section includes two inner pairs of waveguides disposed within that block and separated by an obstruction lying in the last-mentioned E-plane. The higher-frequency wave emitted by the inner waveguides is made planar by a lens disposed at n output aperture of the structure which is transparent to the lower-frequency wave. In a Cassegrain-type radar antenna the lower-frequency wave emitted by the source is returned by a semitransparent intermediate reflector toward a main reflector provided with a grid which rotates its plane of polarization to let it pass out through the intermediate reflector along with the higher-frequency wave which, passing unattenuated through the intermediate reflector, is returned by a solid outlying reflector to the main reflector. |
