EGGBEATER II TPM II: Personal Experience with Satellite Operation
EA4CYQ's three-year journey into amateur radio satellite operation, detailing antenna builds and field results.
Description
Operating amateur radio satellites presents unique challenges, particularly concerning antenna design and signal propagation. Juan Antonio Fernández Montaña, EA4CYQ, recounts his three-year journey into satellite communication, starting with initial guidance from EB4DKA. His early experiments involved a portable 1/4 wave VHF antenna with four 1/4 wave ground planes, designed for hand-held use to adjust polarity. This setup, paired with an FT-3000M transceiver, allowed full-duplex operation on VHF transmit and UHF receive, proving effective for early contacts on satellites like AO27, UO14, and SO35.
EA4CYQ's experience highlights the critical role of coaxial cable loss and antenna polarization. After encountering significant signal degradation with longer RG213 runs, he experimented with a 1/2 inch commercial cable, noting improved reception but persistent fading due to varying satellite polarities. This led to the construction of an Eggbeater II antenna, an omnidirectional UHF design offering horizontal polarization at the horizon and circular right polarization at higher elevation angles. Subsequent modifications resulted in the directional TPM2 antenna, which provided sufficient gain for LEO satellites with a wide 30-degree lobe, enabling consistent contacts from his home station.
The article concludes with practical insights on the performance of the Eggbeater II for both UHF and VHF, and the TPM2 for UHF, emphasizing their utility for portable and fixed operations. EA4CYQ's journey underscores the iterative process of antenna development and the importance of adapting designs to overcome real-world propagation challenges in satellite communications.