An Improved S-Band CubeSat Communication Subsystem Design and Implementation

In the past decade, the majority of the launched satellites have a weight exceeds 1 Ton. Its development takes a long time, high cost, and has a large risk of failure, and does not allow for testing new technologies to avoid the mission's failure. From these points of view, space-tested technologies were preferred to mitigate the risk of failure. Our goal is to build and test our own S-band communication subsystem for CubeSat. The system should be developed with reliable and compact hardware and flexible and efficient software. It consists of passive components such as the antennas and the filters and other active components. The passive components are designed, fabricated and measured while the active components are based on commercial components. In this paper, two antenna boards are designed; one board faces the earth and the other board lies on the opposite side. Each board has two antennas; transmitter and receiver antennas. The transmitter/receiver antennas are operating in the downlink /uplink at frequency bands from 2.2 GHz to 2.29 GHz and from 2.025 GHz to 2.11 GHz, respectively. This configuration keeps the communication between the CubeSat and the ground station to facilitate the de-tumbling process of the CubeSat. The second component is the filters that separate the transmitter from the receiver. The two filters have high roll off and narrow fractional bandwidth within a compact area. The transceiver system is based on the analog devices chip AD9361 controlled by zynq-7000 FPGA. The output RF signal is amplified to approach 33dBm output power to the antenna port via QORVO chip that operates in the range from 700MHz to 2700MHz. The antennas and filters are fabricated and tested where good results are noticed so that they are ready for integrating with the whole CubeSat communication subsystem.