Session
Session VII: Advanced Technologies I
Location
Utah State University, Logan, UT
Abstract
Large RF apertures have long proven to be a vexing challenge for small satellite/CubeSat platforms due to inherent mass and volume restrictions which has limited their use in SAR imaging, RF communications, and astronomy. Fixed apertures are fundamentally limited by the size of the platform itself so these restrictions drive the satellite designer to deployable apertures within which two primary classes exist: mechanical deployables and inflatable balloons. The primary trade between the two is packed volume and surface precision/accuracy per deployed aperture area. Inflatables offer significantly better packed volume than a mechanical deployable, but it is significantly harder to realize high precision surfaces. This paper details an axisymmetric array-fed confocal parabolic Gregorian reflector inflatable antenna system that has been designed, built, and characterized in the RF for potential space deployment from a small-sat payload. The system features three individual inflation chambers, a 2.4 meter primary reflector chamber, an independently adjustable 0.25 meter sub-reflector, and a 2.7 meter diameter torus that packs down to ~1.25U, making use of this system feasible on many CubeSat platforms. The innovative implementation of the Gregorian design relaxes the fabrication tolerances required to achieve good RF performance. A novel approach for post-assembly correction of fabrication defects in the primary reflector has also been developed. Initial prototypes demonstrated approximately 38 dBi of gain with a ~1degree beamwidth at 10 GHz. This represents an improvement in realized gain of greater than 13 dBi, 6 dB improvement in primary reflector surface efficiency, while also increasing reflector aperture diameter by a factor of 2.4 over recent literature. A path forward to improve the manufacturing design to achieve higher performance at X-band and enable Ku-band capability is also discussed as well as considerations for deployment and use in a space environment.
Space-Deployed Inflatable Dual-Reflector Antenna: Design and Prototype Measurements
Utah State University, Logan, UT
Large RF apertures have long proven to be a vexing challenge for small satellite/CubeSat platforms due to inherent mass and volume restrictions which has limited their use in SAR imaging, RF communications, and astronomy. Fixed apertures are fundamentally limited by the size of the platform itself so these restrictions drive the satellite designer to deployable apertures within which two primary classes exist: mechanical deployables and inflatable balloons. The primary trade between the two is packed volume and surface precision/accuracy per deployed aperture area. Inflatables offer significantly better packed volume than a mechanical deployable, but it is significantly harder to realize high precision surfaces. This paper details an axisymmetric array-fed confocal parabolic Gregorian reflector inflatable antenna system that has been designed, built, and characterized in the RF for potential space deployment from a small-sat payload. The system features three individual inflation chambers, a 2.4 meter primary reflector chamber, an independently adjustable 0.25 meter sub-reflector, and a 2.7 meter diameter torus that packs down to ~1.25U, making use of this system feasible on many CubeSat platforms. The innovative implementation of the Gregorian design relaxes the fabrication tolerances required to achieve good RF performance. A novel approach for post-assembly correction of fabrication defects in the primary reflector has also been developed. Initial prototypes demonstrated approximately 38 dBi of gain with a ~1degree beamwidth at 10 GHz. This represents an improvement in realized gain of greater than 13 dBi, 6 dB improvement in primary reflector surface efficiency, while also increasing reflector aperture diameter by a factor of 2.4 over recent literature. A path forward to improve the manufacturing design to achieve higher performance at X-band and enable Ku-band capability is also discussed as well as considerations for deployment and use in a space environment.
