ANTENNAS FOR THE GEMINI VHF-UHF POLARIZATION EXPERIMENT (D-14).
NAVAL RESEARCH LAB WASHINGTON D C
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An experiment was conducted to measure the spatial and temporal distribution of free electrons in the lower layers of the ionosphere. This study used a Gemini spacecraft as a platform from which signals at 133.9 Mc and 401.7 Mc were transmitted. A single antenna a boom-mounted colinear-fed dipole was used to transmit linearly polarized signals at both of the desired frequencies. The effort in designing this antenna was centered chiefly on attempts to achieve polarization purity in the transmitted signal. The proximity of the Gemini spacecraft acting as a reflector introduced an undesirable component of cross-polarization to the signal. By careful design and orientation of the antenna-spacecraft configuration, this cross-polarized component was minimized. The spacecraft-launched signals were received on 28-foot parabolic antennas at two separate ground stations. The reflectors and pedestals were commercially-manufactured. Dual-frequency crossed-dipole feeds were designed and built for these reflectors. Author
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