t be speci fied in advance according to Chapter B4-DV-20-A Bevel-helical gear reducers B4

Flender/Flender Gear Units/Bevel-helical gear reducers B4

um basis for numerical estimation of the corresponding valuesat3 5and 1 7 GHz Theerrors resultingfrom that procedureforthevolumeestimation are expected to be much smaller than 5% Scanning happens with the aid of two parabolic mirrors installed in continuously rotating cylinder (Fig. 1 ) Beyond both front sides of the cylinder, identical three channel receivers are laced whicharecoupled tothe parabolicmirrorsvia plane reflectorand through holesatthe gont sides This scanning principle should be particularly advantageous with respect to the stem inte ration into the aircraft and the erational use It avoids oscillating movements of tle main rejectors or rotational switchesanf uarantees redundance in the case of failure of receiver channels Further it supports simple %ut very effective method for continuous calibra- tion. swath width of 4m is achieved for an altitude of 3m (1OOOft) Thecalibration ofthe radiometeroutputsignals isdone by usin hot loadatambienttemper- ature and Peltier-cooled cold load The hot load consists of sjeet of absorbing material that ~~ ~~ ~ __ ~ ____ ~ 2 , *- COLD LOAD RECEIVER GROUP Fig 1 Perspective representation of the MWR configuration developed Two arabolic reflectors in rotating cylinder and two receiver groups realize two scanlines per revolution Thermarhotkold sources are used for continuous calibration is mounted on the inner wall of the radiometer main rack. As the effective area of the cold load is much smaller, further mirror is usedforfocussing the beams ofthe rotating antennas onto the cold load. During each revolution of the cylinder complete series of hot/cold measure- ments for all frequency channels is accomplished. The sky radiometer is calibrated by the same principle. However, here waveguide ferrite switches are used to switch the radiometer input to the loads. The cold load consists of wave- guide absorber that is also cooled by 3-stage Peltier element. To obtain optimum radiometr