A 6–40 GHz antenna system for CubeSat radiometer

A high-gain 6–40 GHz circularly polarized antenna system has been designed for a CubeSat Radiometer Radio Frequency Interference (RFI) Technology Validation mission, which is to demonstrate wideband (6–40GHz) RFI mitigating backend technologies vital for future space-borne microwave radiometers. In stowed configuration, the antenna system needs to fit within a small volume of 10cm (L) by 8cm (W) by 5cm (H). The deployed length of the antenna is 25cm. The total antenna payload including deployment mechanism needs to be less than 0.2kg. The desired gain is 14 dBic gain at 6 GHz and linearly increased to 22 dBic at 40 GHz in order to minimize the coverage footprint on earth. The proposed antenna system include three continuous-taper helical antennas due to its simple feeding, circular polarization (CP), and wide bandwidth. They also have desirable light weight and flexible structures. The three helical elements operate at 6–11 GHz, 11–22 GHz and 21–40 GHz, respectively. The diameter of each helical antenna is specially profiled as a function of height to achieve the desired linear gain vs. frequency property. Since the three antenna elements are co-located within a small cavity, their positions were carefully investigated to minimize mutual coupling and coupling to cavity. This paper presents the antenna design specifications, simulated performances, and preliminary measurement data.