Horn antenna with low sidelobe response for observations of diffuse celestial radiation.

ABSTRACT

A horn antenna with low sidelobe response has been fabricated for a rocket-borne observation of the diffuse brightness of the sky at submillimeter wavelengths. The antenna consists of a Winston concentrator which defines the field of view and a flared baffle which minimizes diffraction. The sidelobe response for lambda = 337 microm was measured to be <10(-9) at an angle of 70 degrees from the optical axis. Calculations are reported which illustrate the contributions of diffraction and scattering to the sidelobe response.