Investigation of factors contributing depolarization in offset reflector antenna and trimmed-reflector offset parabolic antenna with lower cross-polarization

Abstract

This article outlines impact of various factors on cross-polarization characteristics of offset reflector antenna for communication spacecraft with smaller sized bus at C band. Effects of different parameters are considered in rigorous analysis of the antenna. Measured and predicted performances are found in agreement. To fulfill specific requirement of higher edge-of-coverage gain (>26 dBi) and higher cross-polarization discrimination (XPD > 30 dB) over a wider coverage and dual linear polarization under the imposed constraints, a novel trimmed-reflector offset parabolic antenna (TROPA) is devised. This interesting configuration is obtained by trimming both sides parallel to symmetrical plane of a parabolic offset reflector antenna. Parametric study of trimming distance versus its impact on cross-polarization is also presented. The TROPA acquires wider bandwidth, simplification in its mechanical design and manufacturing, and offers low weight and compactness. It is also shown that trimmed reflector has almost even RF performance in presence of spacecraft body and other antenna. V C 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE 00:000-000, 2012.

Microstrip patch antenna feed for offset reflector antenna for dual band application

“…Multimode waveguide horns are generally used as matched feed for reducing cross‐polar radiation in offset reflectors. Higher order modes along with the dominant mode are generated with proper excitation coefficients in horns to tackle the cross‐polarization problem …”

“…Higher order modes along with the dominant mode are generated with proper excitation coefficients in horns to tackle the cross-polarization problem. [3][4][5][6][7][8][9][10][11][12]…”

Matched feeds for offset reflector antenna using circular microstrip patch antenna

“…An offset reflector when illuminated with linearly polarized plane wave generates asymmetric fields at the focal plane of the reflector. This asymmetric field can be compensated by addition of higher order modes with similar field distribution in appropriate ratio along with the dominant mode in the reflector feed . Dual‐mode horn antenna feed for the offset reflector uses the concept of CFM to achieve low level of cross‐polarization .…”