Bias Horn Pillbox Feed

In this paper a novel feed which can work in two bands has been discussed. This style of feed obtains radiation beam with two different directions by using radiation aperture of the same structure. Combining with a well designed secondary reflecting body this feed can obtain the required antenna secondary pattern. This antenna adopts tangent bend parabolic. It is able to works in two bands; one is H band with horizontal polarization, the other is I band with vertical polarization. It can realize the whole airspace admiralty radar searching with narrow beam that required in the horizontal plane; wide beam covers the low altitude area in the vertical plane and overcomes the disadvantages of two traditional antenna styles. By actual measurement, pattern characteristics of feed horn can satisfy the requirement of the reflection antennas which fit the feed horn. The most significant feature of this style of feed is compact structure, using this feed to improve the design of traditional low altitude blind zone compensation radar antenna. This structure greatly decreases the barrier of feed for the antenna secondary beam. It is very useful to improve the performance of secondary beam. The feed horn studied in this paper has been applied in a novel radar system, And obtained good result. In this paper, calculation method of aperture field has been given, and an improvement design of bias horn pillbox feed is demonstrated. By modifying the feed aperture design procedure. It improves the symmetrical of aperture amplitude to decrease the phase difference of the aperture plane, and finally improve the symmetrical of radiation beam. Also the corresponding OMT has been designed. by optimization simulation, it obtained a well VSWR characteristic.