Early experiments with W-band satellite links

This paper deals with possible ways to implement a low-cost W-band experiment on board a nano-satellite injected in LEO (low Earth orbit). The aim of the experiment, which has obvious limitations in scope and scientific relevance, is to be able to early prove that links at W-band can be conducted between space and ground, and to get a first insight of the operational problems posed by these frequencies. An independent study has been conducted by the authors to outline a few alternatives to design and develop simplified and commercial-off-the-shelf (COTS)-based W-band mini-payloads compatible with a medium-high performance nano-satellite. In this context, three W-band payloads options were considered: an almost pure beacon transmitter; a modulated beacon transmitter and a regenerative repeater. The payloads preliminary designs were considered along with the ground terminals counterpart, being the two segments highly correlated and interdependent. The system design parameters, allow establishing one-way or two-way radio links with the nano-satellite during the overpasses of the ground terminals, were critically considered for their compatibility with the accommodation capabilities and features of the prospective nano-satellite and with the availability of COTS RF (radio frequency) hardware, in particular above 50 GHz. The study has shown that all three alternatives are compatible with the typical accommodation envelope of a 3-axis stabilized nano-satellite in the 20 to 30 kg range, providing a power of 15-20 W to the host payload. Obviously both beacon versions can be accommodated much more easily on board the nano-satellite due to their modest requirements, which inherently implies that the nano-satellite could also embark other experiments. The true regenerative transponder is, instead, more challenging and tends to ´saturate´ the capabilities of the ´reference´ nano-satellite. On the other hand, its configuration and operating modes can considerably increase th- - e experiment value that could also become amenable through refurbishments and suitable modifications, to further W-band experiments on board more ambitious experimental satellites