Session
Poster Session 2
Location
Salt Palace Convention Center, Salt Lake City, UT
Abstract
As CubeSat missions demand higher data rates, directional patch antennas have increasingly replaced traditional monopole or dipole antennas, and ensuring omnidirectional coverage—especially under tumbling conditions—has become critical. To address this, we developed a three-dimensional radiation pattern measurement system that enables the evaluation of antenna characteristics across all possible CubeSat attitudes. To apply these measurements to practical operations, we introduce the Coverage Ratio of CubeSat Attitude (CRCA), which intuitively represents the percentage of satellite orientations that exceed a given required gain. In this study, we apply this methodology to the S-band downlink antenna system of VERTECS, a 6U CubeSat developed by the Kyushu Institute of Technology in collaboration with other institutions. The measured results show that a gain of –7.0 dBic or higher is achieved in 50% of all possible attitudes, demonstrating sufficient coverage under tumbling conditions. Incorporating this value into the link budget confirms that stable communication can be maintained with a positive link margin even in the worst-case scenario. These findings highlight the importance of three-dimensional antenna characterization and system-level evaluations in ensuring reliable CubeSat communications. Future work includes in-orbit validation of the link budget and estimation of the expected downlink data volume through combined orbital and attitude simulations.
Document Type
Event
Three-Dimensional Radiation Patterns of CubeSats and Link Budget Without Attitude Control
Salt Palace Convention Center, Salt Lake City, UT
As CubeSat missions demand higher data rates, directional patch antennas have increasingly replaced traditional monopole or dipole antennas, and ensuring omnidirectional coverage—especially under tumbling conditions—has become critical. To address this, we developed a three-dimensional radiation pattern measurement system that enables the evaluation of antenna characteristics across all possible CubeSat attitudes. To apply these measurements to practical operations, we introduce the Coverage Ratio of CubeSat Attitude (CRCA), which intuitively represents the percentage of satellite orientations that exceed a given required gain. In this study, we apply this methodology to the S-band downlink antenna system of VERTECS, a 6U CubeSat developed by the Kyushu Institute of Technology in collaboration with other institutions. The measured results show that a gain of –7.0 dBic or higher is achieved in 50% of all possible attitudes, demonstrating sufficient coverage under tumbling conditions. Incorporating this value into the link budget confirms that stable communication can be maintained with a positive link margin even in the worst-case scenario. These findings highlight the importance of three-dimensional antenna characterization and system-level evaluations in ensuring reliable CubeSat communications. Future work includes in-orbit validation of the link budget and estimation of the expected downlink data volume through combined orbital and attitude simulations.
