Which of the following statements about parabolic reflector systems are correct?
1. A front-fed shallow parabolic reflector antenna requires a feed horn with narrow radiation pattern relative to that for a deep dish
2. The noise temperature of a Cassegrain system is the highest when it looks at the horizon
3. The noise temperature of a front-fed parabolic antenna is the lowest when it looks at the Zenith
4. The sidelobe level of a parabolic reflector is highest for uniform aperture illumination
Select the correct answer using the codes given below: