W.A. Shiroma

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A full-duplex dual-frequency self-steering array using phase detection and phase shifting is presented. By RF decoupling the transmitter and receiver arrays, the proposed system promises greater system efficiency by ensuring a constant transmit power. This also allows for a separate low-frequency interrogating signal capable of various modulation schemes. A(More)
Distributed nanosatellite networks have the advantage of being reconfigurable, redundant, and readily deployable. Two types of antennas designed for this application are presented: a flexible UHF antenna for Earth-to-satellite communications, and an X-band retrodirective array for secure satellite-to-satellite crosslink communications.
A 2-D retrodirective array based on phase detection and heterodyne scanning is presented. The system integrates two single voltage-controlled oscillator phase-shifting networks that are autonomously controlled via a phase-detecting array and control circuit that eliminates the R<sup>4</sup> path loss typical of other retrodirective arrays. Retrodirectivity(More)
A high-directivity combined self-beam/null-steering array for secure point-to-point binary phase-shift keying communications is introduced. The system provides high directivity and reduced probability of interception using just two antenna elements. Using quadrature phase-shift keying modulators allows for compact single-layer fabrication. The 2.4-GHz(More)
The ability of a phase-conjugating array (PCA) to reduce fading in single-reflector, dual-reflector, and blocked-line-of-sight multipath environments is presented. Compared to a reference four-element antenna array, the PCA improves worst case signal fading by as much as 39 dB. Agreement between the experimental results and a ray-tracing model is observed,(More)
A design for a coupled interrogator/receiver for a retrodirective system is presented. The design consists of two coupled patch antennas for interrogation and receiving, together with the associated electronic hardware. The application is for retrodirective crosslinks in a secure nanosatellite network.
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