A Compact CubeSat Antenna with Beamsteering Capability and Polarization Agility: Characteristic Modes Theory for Breakthrough Antenna Design

In this article, we propose a novel compact radiating system for a 1 U CubeSat. The designed antenna benefits from characteristic modes theory (CMT), which provides guidelines to advantageously exploit the hosting platform as part of the radiating system. The effect of the small satellite on the resonance frequency and pattern shape is therefore intrinsically taken into account. The employed inductive-coupling exciters are nonresonant half-loops that offer a huge saving in terms of space and weight requests. Additionally, the proposed S-band antenna provides the remarkable feature of scan-beam capability, in circular polarization (CP) as well as linear polarization (LP), which is not found in any other compact radiator. The overall angular coverage spans more than 90° with an axial ratio (AR) lower than 3 dB and within the half-power beamwidth (HPBW), and therefore a 360° angular coverage is guaranteed if four of these minimally invasive radiators are placed on the small satellite. Measurements are in positive agreement with simulations and confirm the estimated good performance of this innovative solution.