Ralf Christian Wilke

Multi-layer patch antenna array design for Ka-band satellite communication

The GeReLEO-SMART project aims to build a communication experiment to be launched on the German technology demonstration mission “Heinrich-Hertz” (H2SAT). On its geostationary orbit it will demonstrate new space appropriate technology of a 26 GHz patch antenna array with integrated low noise amplifiers (LNA), MEMS switching of the RF signal and FPGA mission control. The antenna consists of a multi-layer structure including a pre selector band pass filter to suppress other radio sources on the Heinrich-Hertz satellite. The reception antenna consists of five 2×2 array of circular patch antennas with a feeding network. A temperature stabilized LNA is buried into the PCB stack to minimize transmission line losses in front of it. Two different designs of the antenna array are presented to compare the space qualification by real tests and measurements.

Far field analysis of wrinkles in space membrane antennas

Large deployable antennas (LDA) are an upcoming technique used as space borne reflector antennas. Low stow volume and mass are one of the key advantages allowing big reflector diameters to be launched on conventional vehicles. A primary concern in reflector antenna building is surface accuracy, especially at high operating frequencies. Conventional LDA use sophisticated high cost mechanics to deploy a mesh structure with low surface error. But deployable structures are also used as a drag sail to deorbit satellites when their life time is exceeded. The surface structure of such a drag sail is of subordinate interest, leading to low cost deployment mechanics, which are easy to build. The idea described in this paper is to use the drag sail deployment technique and use the expanded membrane surface as a reflector antenna. The effects of the surface errors, which are inevitably introduced by the mechanics, are studied to help to determine a break-even point between antenna performance loss and cost reduction compared to a conventional LDA. Possible applications are small satellites like CubeSats, which could enhance their communication link budget by deploying a medium performance but low cost LDA.

Lightweight and cost efficient spaceborn patch antenna

In order to achieve lightweight yet low cost antennas for use in a geostationary space environment, the GeReLEO-SMART project develops a substrate-based, multilayer antenna structure which can replace traditional horn antennas as feeds for reflector antennas. To verify a design, an example mission is developed, consisting of a 2×2 patch antenna array with an integrated stripline bandpass filter. The operation frequency is 25.935 GHz. This multilayer antenna will be tested on board of the German technology demonstration mission “Heinrich-Hertz” (H2SAT). The design passed all tests for space qualification without decrease in performance.