Design of offset reflector with elliptical flat scan mirror and its applications to a dual-frequency, dual-polarization airborne rain radar observations

Design and development of a dual-frequency (Ku/Ka), dual-polarization, wide-angle scanning airborne rain radar antenna system

“…Details of antenna RF performance can be found in [1]. A comparison between measured and theoretical results based on PO technique of the antenna's principal plane radiation patterns at Ku-and Ka-band is shown in Figures 5a and b respectively [1]. As can be seen, very good agreement between both results are obtained.…”

“…The elliptical, flat plate is mechanically rotated in azimuth (electronically driven by a motor) to scan the antenna beam in the cross-track direction (+/-25°) for wide-swath coverage, and in elevation to compensate for the motion of the aircraft. The PO analysis [1] shows that the scattered field from the plate in both elevation and azimuth principal plane cuts, for a 45° tilt, agrees very well over the antenna main beam. This is expected, since for a plate at a 45° incline angle, its projected aperture in the x-z plane is circular, and hence one would expect a matched 3-dB beamwidth for elevation and azimuth plane cuts.…”

“…It is anticipated that the angular rotation of the plate in elevation plane, which compensates for the aircraft motion, to be within ±2 degrees from the 45° inclination angle. PO analysis shows that the rotation of the plate within this angular region compensates for the aircraft motion and results in elevation-to-azimuth beamwidth ratio much less than 1.05 [1].…”

“…The measured antenna principal plane cuts for both polarizations and frequencies show match beam and low sidelobe levels (Table 1 and Figures 5 and 6). Details of antenna RF performance can be found in [1]. A comparison between measured and theoretical results based on PO technique of the antenna's principal plane radiation patterns at Ku-and Ka-band is shown in Figures 5a and b respectively [1].…”

“…This experimental system has been flown on NASA's DC-8 aircraft in the configuration shown in Figure 1. This paper focuses on the design and the development of the antenna system [1]. The RF and digital design portion are given in [2].…”