Ian M. Davis

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A lightweight, low-cost, simultaneous X-band and Ka-band feed-system has been designed and matched to a deployable flyaway SATCOM antenna. The performance of the complete antenna assembly has been simulated and the results show that very good performance can be achieved in both X and Ka-band from a relatively small antenna.
S-band has been used for satellite Telemetry, Tracking and Control (TT&C) applications for many years and more recently X-band has also been deployed. A theoretical design for a new dual S/X-band feed-system for a ground station with S-band transmit and receive capabilities and X-band receive capabilities is presented.
Dual and multi-band feed systems that enable reflector antennas to operate over multiple frequency bands have been used for some time. With newer generations of satellites, there is an increased demand for these types of feeds in satellite communications. At the same time, the requirements for performance such as bandwidth and band separation are becoming(More)
A dual X/Ka-band feed system suitable for large Earth Station SATCOM antennas has been developed. The feed system is suitable for simultaneous four-port operation over both X- and Ka-band and supports monopulse tracking at Ka-band. Secondary radiation patterns on a representative 13m class reflector have been calculated and compared with the requirements(More)
New requirements for wide band operation in areas such as SATCOM, EW, and radio astronomy are stretching the capability of traditional horn antenna designs. New horn types are being developed to meet these requirements. Two examples are presented: the smooth-walled profiled horn and the “bullet” horn.
A strategy to optimize dual-reflector antennas for compact Satellite Communications (SATCOM) terminals to meet various user-specified requirements is described. An overview of the method and design methodology is given, and some of the challenges in designing compact antennas as compared to traditional large Earth Station antennas are described.
Direct spillover from the feed past the edge of the subreflector can create sidelobes that exceed the sidelobe template requirements for typical SATCOM ground-terminal dual-reflector antennas. “Some rules of thumb” are given to the antenna designer for choosing the subreflector edge-illumination taper, to ensure that the design of the(More)
The Defence Science and Technology Organisation (DSTO) recently had a requirement for its X-band capabilities to be upgraded. The solution was to re-band an existing Ku-band earth-station antenna for X-band operation. BAE Systems Australia and DSTO worked closely to meet a very tight delivery deadline. The initial requirement was for a receive capability(More)
Sumatriptan exhibits low oral bioavailability partly due to presystemic metabolism, which may vary with regional differences in metabolic activity throughout the gastrointestinal tract. This study evaluated sumatriptan absorption in humans after administration orally and by oroenteric tube into the jejunum and cecum. Because the site of cecal administration(More)
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